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The Truth About Taking Vitamins

Many of us do this every day. But is it a good idea?

Multivitamins and single vitamins are some of the most popular supplements in the U.S. In a summer 2022 nationally representative Consumer Reports survey (PDF) of 3,070 U.S. adults, about half of people said they take multivitamins and 42 percent said they take individual vitamins— for everything from improving general health and boosting immunity to preventing COVID-19. While experts agree that most Americans don’t eat enough vitamin-rich foods, research shows that vitamin supplements might not be a great way to bridge the gap. And people who take higher doses of certain vitamin supplements actually have a higher risk of adverse health outcomes. In the U.S., the days of widespread vitamin deficiencies causing conditions like scurvy and rickets are long gone. If you have a deficiency, a doctor may recommend a vitamin. But many ailments, including certain cancers, heart disease, and diabetes, stem from multiple factors and don’t seem to be prevented or treated with vitamins. Unless you have certain medical conditions or a restrictive diet, vitamin supplements are generally not helpful, says Fang Fang Zhang, MD, chair of the division of nutrition epidemiology and data science at Tufts University in Boston. Still, there are some exceptions. One key caution: If you take vitamins, avoid mega-dosing, Zhang says. That could cause stomach upset or organ damage, or even increase cancer risk. “More isn’t always better,” Zhang says. Here’s what to consider.

The Research on Multivitamins

“A lot of my patients take multivitamins because they see them almost as an insurance policy to guarantee they get all the nutrients they need,” says Kenneth Koncilja, MD, a geriatrician at the Cleveland Clinic.

A 2020 study published in the journal BMJ Open found that people who took these over-the-counter (OTC) product­s—which contain all or most recognized vitamins and minerals —reported better overall well-being. But most research doesn’t bear this out. The BMJ study found no measurable health benefits for users.

A series of papers published in 2013 in the Annals of Internal Medicine that looked at multivitamin use among tens of thousands of people found that they didn’t reduce the risk of heart disease , cancer , or cognitive decline . And a 2018 editorial in the journal JAMA that reviewed the research concluded that healthy adults 50 and older simply don’t need a multivitamin.

“When you put multivitamins to the test, research shows there’s no benefit, and there even might be some chance of harm,” says Edgar Miller III, PhD, MD, a professor of medicine and epidemiology at Johns Hopkins University.

Special Situations

A multi may be helpful in a few cases—say, after gastric bypass surgery or for severe malnutrition due to cancer—but most of the time you’re best off getting nutrients from a balanced diet , Koncilja says. Still, evidence suggests that some adults may benefit from certain single-ingredient supplements. If your doctor recommends one, check the product for certification or verification from a third-party group like the U.S. Pharmacopeia or NSF International . These include:

Vitamin B12

Adults older than 60 may have difficulty absorbing this vitamin (found in fish, meat, poultry, eggs, and dairy), so they’re more likely to be deficient, says Nisha Rughwani, MD, an associate professor of geriatrics and palliative care medicine at the Icahn School of Medicine at Mount Sinai in New York City. If tests show that your blood levels are under 300 picograms per milliliter (pg/mL), you’ll probably need a supplement, she says. Extremely low levels may call for temporary B12 injections. People with autoimmune disorders, like rheumatoid arthritis, or those with alcoholism might also need extra B vitamins. And during pregnancy, doctors recommend folic acid (vitamin B9) to help prevent birth defects.

Fatty fish and fortified milk have vitamin D , and exposure to sunlight triggers your skin to produce it. But it’s hard to get the recommended daily amount for adults older than 70 (800 international units, or IU) this way, Koncilja says. If you take a vitamin D supplement, be aware that a significantly higher intake can hike kidney stone risk. If you use a combined vitamin D and calcium supplement , be aware that supplemental calcium has been linked to a higher risk of colon polyps, kidney stones, and calcium buildup in the heart’s arteries, Miller says.

A bit more than 10 percent of people older than 65 have anemia. If you suspect you have it (signs are weakness, headache , fatigue, shortness of breath and rapid heartbeat during exercise, and brittle nails) ask your doctor about testing to determine whether you need an iron supplement. “You don’t just want to take it on your own, as iron tablets can cause constipation and stomach pain, nausea, and vomiting,” Rughwani says.

This antioxidant supports immune system function. Most people get enough by eating produce. But smokers or people exposed to secondhand smoke, people with renal disease, and others who have issues with vitamin absorption tend to have lower levels and may need a supplement.

An antioxidant, vitamin E helps the immune system fight off certain illnesses and infections. It’s in vegetable oils, nuts, and green vegetables. Though most people don’t get enough, supplementing hasn’t proved to be beneficial in healthy people. People with rare disorders that impede fat absorption, and premature infants under the care of a physician may benefit from a supplement, however.

Can You Trust Label Claims?

OTC supplements aren’t regulated by the Food and Drug Administration the way that prescription medications are. And 12 of the 27 multivitamin and mineral supplements analyzed in 2020 by ConsumerLab.com were found to have quality problems, such as having more or less of the vitamins and minerals than their labels claimed. Some may also contain contaminants.

@consumerreports CR science journalist Catherine Roberts explains why you should reconsider buying yet another bottle of multivitamins. Learn more through the link in our bio. #healthtok #multivitamin #sciencetok #sciencetiktok ♬ original sound - Consumer Reports

Editor’s Note:  A version of this article also appeared in the June 2021 issue of  Consumer Reports On Health . It was updated with content from the January 2023 issue of Consumer Reports magazine. 

Hallie Levine

Hallie Levine is an award-winning magazine and freelance writer who contributes to Consumer Reports on health and fitness topics. Her work has been published in Health, Prevention, Reader's Digest, and Parents, among others. She's a mom to three kids and a fat but feisty black Labrador retriever named Ivry. In her (nonexistent) spare time, she likes to read, swim, and run marathons.

Ashley Abramson

Ashley Abramson is a freelance writer focused on health and psychology. In addition to Consumer Reports, she's written for the New York Times, the Washington Post, and the Guardian. She lives in Milwaukee with her husband, two young sons, and their pair of pups. When she's not writing, she enjoys good food, movies, and the Lake Michigan views down the street.

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Vitamins and Minerals

Vitamins and minerals are micronutrients required by the body to carry out a range of normal functions. However, these micronutrients are not produced in our bodies and must be derived from the food we eat.

Vitamins are organic substances that are generally classified as either fat soluble or water soluble. Fat-soluble vitamins ( vitamin A , vitamin D , vitamin E , and vitamin K ) dissolve in fat and tend to accumulate in the body. Water-soluble vitamins ( vitamin C and the B-complex vitamins , such as vitamin B6 , vitamin B12 , and folate ) must dissolve in water before they can be absorbed by the body, and therefore cannot be stored. Any water-soluble vitamins unused by the body is primarily lost through urine.

Minerals are inorganic elements present in soil and water, which are absorbed by plants or consumed by animals. While you’re likely familiar with calcium , sodium , and potassium , there is a range of other minerals, including trace minerals (e.g. copper , iodine , and zinc ) needed in very small amounts.

In the U.S., the National Academy of Medicine (formerly the Institute of Medicine) develops nutrient reference values called the Dietary Reference Intakes (DRIs) for vitamins and minerals. [1] These are intended as a guide for good nutrition and as a scientific basis for the development of food guidelines in both the U.S. and Canada. The DRIs are specific to age, gender, and life stages, and cover more than 40 nutrient substances. The guidelines are based on available reports of deficiency and toxicity of each nutrient. Learn more about vitamins and minerals and their recommended intakes in the table below.

What about multivitamins?

A diet that includes plenty of fruits, vegetables , whole grains , good protein packages , and healthful fats should provide most of the nutrients needed for good health. But not everyone manages to eat a healthful diet. Multivitamins can play an important role when nutritional requirements are not met through diet alone. Learn more about vitamin supplementation .

Did you know? 

Vitamins and their precise requirements have been controversial since their discovery in the late 1800s and early 1900s. It was the combined efforts of epidemiologists, physicians, chemists, and physiologists that led to our modern day understanding of vitamins and minerals. After years of observation, experiments, and trial and error, they were able to distinguish that some diseases were not caused by infections or toxins—a common belief at the time—but by vitamin deficiencies. [2] Chemists worked to identify a vitamin’s chemical structure so it could be replicated. Soon after, researchers determined specific amounts of vitamins needed to avoid diseases of deficiency.

In 1912, biochemist Casimir Funk was the first to coin the term “vitamin” in a research publication that was accepted by the medical community, derived from “vita” meaning life, and “amine” referring to a nitrogenous substance essential for life. [3] Funk is considered the father of vitamin therapy, as he identified nutritional components that were missing in diseases of deficiency like scurvy (too little vitamin C ), beri-beri (too little vitamin B1 ), pellagra (too little vitamin B3 ), and rickets (too little vitamin D ). The discovery of all vitamins occurred by 1948.

Vitamins were obtained only from food until the 1930s when commercially made supplements of certain vitamins became available. The U.S government also began fortifying foods with specific nutrients to prevent deficiencies common at the time, such as adding iodine to salt to prevent goiter, and adding folic acid to grain products to reduce birth defects during pregnancy. In the 1950s, most vitamins and multivitamins were available for sale to the general public to prevent deficiencies, some receiving a good amount of marketing in popular magazines such as promoting cod liver oil containing vitamin D as bottled sunshine.

• Dietary Reference Intakes for Calcium, Phosphorous, Magnesium, Vitamin D, and Fluoride (1997); Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline (1998); Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids (2000); Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc (2001); and Dietary Reference Intakes for Calcium and Vitamin D (2011) . These reports may be accessed via www.nap.edu .
• Semba RD. The discovery of the vitamins. Int J Vitam Nutr Res . 2012 Oct 1;82(5):310-5.
• Piro A, Tagarelli G, Lagonia P, Tagarelli A, Quattrone A. Casimir Funk: his discovery of the vitamins and their deficiency disorders. Ann Nutr Metab . 2010;57(2):85-8.

Last reviewed March 2023

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Vitamins and human health: systematic reviews and original research.

Conflicts of Interest

• Venturelli, S.; Leischner, C.; Helling, T.; Burkard, M.; Marongiu, L. Vitamins as Possible Cancer Biomarkers: Significance and Limitations. Nutrients 2021 , 13 , 3914. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Gil Martínez, V.; Avedillo Salas, A.; Santander Ballestín, S. Vitamin Supplementation and Dementia: A Systematic Review. Nutrients 2022 , 14 , 1033. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Sinopoli, A.; Caminada, S.; Isonne, C.; Santoro, M.M.; Baccolini, V. What Are the Effects of Vitamin A Oral Supplementation in the Prevention and Management of Viral Infections? A Systematic Review of Randomized Clinical Trials. Nutrients 2022 , 14 , 4081. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Ali, M.A.; Hafez, H.A.; Kamel, M.A.; Ghamry, H.I.; Shukry, M.; Farag, M.A. Dietary Vitamin B Complex: Orchestration in Human Nutrition throughout Life with Sex Differences. Nutrients 2022 , 14 , 3940. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Ledowsky, C.; Mahimbo, A.; Scarf, V.; Steel, A. Women Taking a Folic Acid Supplement in Countries with Mandatory Food Fortification Programs May Be Exceeding the Upper Tolerable Limit of Folic Acid: A Systematic Review. Nutrients 2022 , 14 , 2175. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Vargas-Uricoechea, H.; Nogueira, J.P.; Pinzón-Fernández, M.V.; Agredo-Delgado, V.; Vargas-Sierra, H.D. Population Status of Vitamin B12 Values in the General Population and in Individuals with Type 2 Diabetes, in Southwestern Colombia. Nutrients 2023 , 15 , 2357. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• van Gorkom, G.N.Y.; Boerenkamp, L.S.; Gijsbers, B.; van Ojik, H.H.; Wodzig, W.; Wieten, L.; Van Elssen, C.; Bos, G.M.J. No Effect of Vitamin C Administration on Neutrophil Recovery in Autologous Stem Cell Transplantation for Myeloma or Lymphoma: A Blinded, Randomized Placebo-Controlled Trial. Nutrients 2022 , 14 , 4784. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Sun, R.; Liu, L.; Qian, T.; Zhao, M.; Che, W.; Hou, X.; Xie, H.; Su, Y.; Pan, H.; Li, J.; et al. Protection of Vitamin C on Oxidative Damage Caused by Long-Term Excess Iodine Exposure in Wistar Rats. Nutrients 2022 , 14 , 5245. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Yousef, S.; Colman, I.; Papadimitropoulos, M.; Manuel, D.; Hossain, A.; Faris, M.; Wells, G.A. Vitamin D and Chronic Diseases among First-Generation Immigrants: A Large-Scale Study Using Canadian Health Measures Survey (CHMS) Data. Nutrients 2022 , 14 , 1760. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Głąbska, D.; Kołota, A.; Lachowicz, K.; Skolmowska, D.; Stachoń, M.; Guzek, D. Vitamin D Supplementation and Mental Health in Multiple Sclerosis Patients: A Systematic Review. Nutrients 2021 , 13 , 4207. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Zhu, A.; Kuznia, S.; Niedermaier, T.; Holleczek, B.; Schöttker, B.; Brenner, H. Distribution and Determinants of Vitamin D-Binding Protein, Total, “Non-Bioavailable”, Bioavailable, and Free 25-Hydroxyvitamin D Concentrations among Older Adults. Nutrients 2021 , 13 , 3982. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Amon, U.; Yaguboglu, R.; Ennis, M.; Holick, M.F.; Amon, J. Safety Data in Patients with Autoimmune Diseases during Treatment with High Doses of Vitamin D3 According to the “Coimbra Protocol”. Nutrients 2022 , 14 , 1575. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Kulig, P.; Łuczkowska, K.; Bielikowicz, A.; Zdrojewska, D.; Baumert, B.; Machaliński, B. Vitamin D as a Potential Player in Immunologic Control over Multiple Myeloma Cells: Implications for Adjuvant Therapies. Nutrients 2022 , 14 , 1082. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Renke, G.; Starling-Soares, B.; Baesso, T.; Petronio, R.; Aguiar, D.; Paes, R. Effects of Vitamin D on Cardiovascular Risk and Oxidative Stress. Nutrients 2023 , 15 , 769. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Guzek, D.; Kołota, A.; Lachowicz, K.; Skolmowska, D.; Stachoń, M.; Głąbska, D. Effect of Vitamin D Supplementation on Depression in Adults: A Systematic Review of Randomized Controlled Trials (RCTs). Nutrients 2023 , 15 , 951. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Niedermaier, T.; Gredner, T.; Kuznia, S.; Schöttker, B.; Mons, U.; Brenner, H. Potential of Vitamin D Food Fortification in Prevention of Cancer Deaths—A Modeling Study. Nutrients 2021 , 13 , 3986. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Starek, M.; Gumułka, P.; Dąbrowska, M. Quality Control of the Dietary Supplements Containing Selected Fat-Soluble Vitamins D and K. Nutrients 2023 , 15 , 1650. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Renke, G.; Almeida, V.B.P.; Souza, E.A.; Lessa, S.; Teixeira, R.L.; Rocha, L.; Sousa, P.L.; Starling-Soares, B. Clinical Outcomes of the Deleterious Effects of Aluminum on Neuro-Cognition, Inflammation, and Health: A Review. Nutrients 2023 , 15 , 2221. [ Google Scholar ] [ CrossRef ]

Share and Cite

Barker, T. Vitamins and Human Health: Systematic Reviews and Original Research. Nutrients 2023 , 15 , 2888. https://doi.org/10.3390/nu15132888

Barker T. Vitamins and Human Health: Systematic Reviews and Original Research. Nutrients . 2023; 15(13):2888. https://doi.org/10.3390/nu15132888

Barker, Tyler. 2023. "Vitamins and Human Health: Systematic Reviews and Original Research" Nutrients 15, no. 13: 2888. https://doi.org/10.3390/nu15132888

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June 25, 2024

What Vitamins and Minerals Really Do in Your Body

Humans need around 30 vitamins and minerals to keep our bodies functioning

By Clara Moskowitz , Jen Christiansen & Miriam Quick

Jen Christiansen

Food gives us energy, but just as important, it delivers vitamins and minerals. There is essentially no bodily function that doesn’t depend on at least one of these compounds, roughly 30 of which are considered crucial. They help our hearts beat and our lungs breathe. They enable our bodies to build new muscle, skin and bone cells. They allow nerves to send signals to the brain and the immune system to fight invaders. We literally can’t live without them.

The difference between vitamins and minerals is that the former are organic—made by a plant or animal—and the latter are not. We absorb vitamins directly from the plants and animals we eat. We get minerals, which come from rocks, dirt or water, sometimes from the environment and sometimes from living things we eat that absorbed them before they died.

“Vitamins and minerals work in wild and wondrous ways, some of which we understand, many of which we’re still trying to understand,” says Howard Sesso, associate director of the division of preventive medicine at Brigham and Women’s Hospital and medical editor of the Making Sense of Vitamins and Minerals report from Harvard Medical School. “And there’s tremendous variation in how we all consume, digest, absorb and utilize the nutrients in a particular food we’re eating.”

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Key Functions • Listed here are the main known uses of different nutrients, although scientists suspect there are many that are undiscovered. Furthermore, vitamins and minerals often interact with one another and help to promote the reactions of other nutrients.

CATEGORY: Water-Soluble Vitamins

These vitamins can dissolve in water.

Vitamin B 1 (thiamin) • Helps to turn food into energy. Promotes skin, hair, muscle and brain health. Critical for nerve function. • Rich Food Sources: Pork, brown rice, soy milk, watermelon, acorn squash

Vitamin B 2 (riboflavin) • Helps to turn food into energy. Boosts skin, hair, blood and brain health. • Rich Food Sources: Meat, milk, eggs, yogurt, cheese, green leafy vegetables

Vitamin B 3 (niacin, nicotinic acid, nicotinamide) • Helps to turn food into energy. Essential for healthy skin, blood cells, brain and nervous system. • Rich Food Sources: Meat, poultry, fish, whole grains, mushrooms, potatoes, peanut butter

Vitamin B 5 (pantothenic acid) • Helps to turn food into energy. Helps to produce lipids, neurotransmitters, steroid hormones and hemoglobin. • Rich Food Sources: Chicken, egg yolk, whole grains, broccoli, mushrooms, avocados

Vitamin B 6 (pyridoxine, pyridoxal, pyridoxamine) • Metabolizes amino acids and helps cells replicate. Helps to produce red blood cells and neurotransmitters essential for brain function. • Rich Food Sources: Meat, fish, poultry, legumes, tofu, potatoes, bananas, watermelon

Vitamin B 7 (biotin) • Helps to convert food into energy and make glucose. Helps to build and break down some fatty acids. Promotes bone and hair health. • Rich Food Sources: Whole grains, organ meats, egg yolks, soybeans, fish

Vitamin B 9 (folate, folic acid, folacin) • Metabolizes amino acids and helps cells multiply. Vital for new cell creation. Helps to prevent brain and spine birth defects when taken early in pregnancy. • Rich Food Sources: Asparagus, okra, spinach, turnip greens, broccoli, legumes, orange juice, tomato juice

Vitamin B 12 (cobalamin, cyanocobalamin) • Metabolizes amino acids and helps cells multiply. Protects nerves and encourages their growth. Helps to build red blood cells and DNA. • Rich Food Sources: Meat, poultry, fish, milk, cheese, eggs

Vitamin C (L-ascorbic acid) • Makes collagen, as well as the neurotransmitters serotonin and norepinephrine. Works as an antioxidant. Boosts the immune system. • Rich Food Sources: Fruits (especially citrus), potatoes, broccoli, bell peppers, spinach, strawberries, tomatoes, brussels sprouts

CATEGORY: Water-Soluble Nutrient

Choline is organic and water-soluble, but it’s not classified as either a vitamin or a mineral. It’s somewhat similar to B vitamins.

Choline (formerly called vitamin B 4 ) • Helps to make the neurotransmitter acetylcholine. Aids in metabolizing and transporting fats. • Rich Food Sources: Milk, eggs, liver, salmon, peanuts

CATEGORY: Fat-Soluble Vitamin

These organic nutrients dissolve in fats and oils and are mostly found in fat tissue and the liver.

Vitamin A (retinoids—preformed vitamin A, beta carotene—converts to vitamin A) • Important for vision, cell health, bone formation and immune system function. • Rich Food Sources: Liver, fish, eggs, sweet potatoes, carrots, pumpkins, squash, spinach, mangoes, turnip greens

Vitamin D (calciferol, cholecalciferol—vitamin D 3 , ergocalciferol—vitamin D 2 ) • Helps to keep calcium and phosphorus at normal levels in the blood. Assists in forming teeth and bones. • Rich Food Sources: Fortified milk or margarine, fortified cereals, fatty fish (Your body also uses sunlight to make vitamin D.)

Vitamin E (alpha-tocopherol) • Acts as an antioxidant, aids the immune system and supports vascular health. • Rich Food Sources: Vegetable oils, wheat germ, leafy green vegetables, whole grains, nuts

Vitamin K (phylloquinone—vitamin K 1 , menaquinones—vitamin K 2 ) • Aids in bone formation. Activates proteins and calcium essential for blood clotting. • Rich Food Sources: Cabbage, liver, eggs, milk, spinach, broccoli, sprouts, kale, collards, other green vegetables

CATEGORY: Major Mineral

The body needs relatively large amounts of these minerals, although too much of one can sometimes block the absorption of another.

Calcium • Helps to build and protect teeth and bones. Aids with muscle function, blood clotting, nerve impulse transmission, hormone secretion and enzyme activation. • Rich Food Sources: Yogurt, cheese, milk, tofu, sardines, salmon, fortified juices, broccoli, kale

Chloride • Balances fluids in the body and forms part of the stomach acid, which helps to digest food. • Rich Food Sources: Salt (sodium chloride), soy sauce, processed foods

Magnesium • Necessary for chemical reactions in the body. Aids in muscle contraction, blood clotting and regulation of blood pressure. Helps to build bones and teeth. • Rich Food Sources: Spinach, broccoli, legumes, cashews, sunflower and other seeds, halibut, whole wheat bread, milk

Phosphorus • Builds and protects bones and teeth. Forms a part of DNA and RNA. Helps to convert food into energy. Helps to move nutrients into and out of cells. • Rich Food Sources: Milk and dairy products, meat, fish, poultry, eggs, liver, green peas, broccoli, potatoes, almonds

Potassium • Helps to balance fluids in the body. Helps to maintain a steady heartbeat and send nerve impulses. Required for muscle contractions. • Rich Food Sources: Meat, milk, fruits, vegetables, grains, legumes

Sodium • Helps to balance fluids in the body. Helps to send nerve impulses. Needed for muscle contractions. Impacts blood pressure. • Rich Food Sources: Salt, soy sauce, processed foods, vegetables

Sulfur • Helps to shape and stabilize protein structures. Necessary for healthy hair, skin and nails. • Rich Food Sources: Protein-rich foods, such as meat, fish, poultry, nuts, legumes

CATEGORY: Trace Mineral

Only small quantities of these are necessary for the body, but they are as essential as the major minerals.

Chromium • Boosts insulin activity, helps to maintain normal blood glucose levels, and is required to free energy from glucose. • Rich Food Sources: Meat, poultry, fish, eggs, potatoes, some cereals, nuts, cheese, brewer’s yeast

Copper • Important for iron metabolism and the immune system. Helps to make red blood cells. • Rich Food Sources: Liver, shellfish, nuts, seeds, whole-grain products, beans, prunes, cocoa, black pepper

Fluoride • Strengthens bones and stimulates new bone formation. Prevents tooth decay. • Rich Food Sources: Fluoridated water, toothpaste with fluoride, marine fish, teas

Iodine • Necessary for synthesizing thyroid hormones, which help to maintain body temperature and influence nerve and muscle function. • Rich Food Sources: Iodized salt, processed foods, seafood

Iron • Helps to transport oxygen through the body. Required for chemical reactions in the body and for making amino acids, collagen, neurotransmitters and hormones. • Rich Food Sources: Red meat, poultry, eggs, fruits, green vegetables, fortified bread and grain products

Manganese • Helps to form bones and metabolize amino acids, cholesterol and carbohydrates. • Rich Food Sources: Fish, nuts, legumes, whole grains, tea

Molybdenum • Forms part of several enzymes, including one that protects against potentially deadly neurological damage in infants. • Rich Food Sources: Legumes, nuts, grain products, milk

Selenium • Acts as an antioxidant and helps to regulate thyroid hormone activity. • Rich Food Sources: Organ meats, seafood, walnuts, sometimes plants (depends on soil content), grain products

Zinc • Helps to form enzymes and proteins and to build new cells. Frees vitamin A from storage in the liver. Vital for the immune system, taste, smell and wound healing. • Rich Food Sources: Red meat, poultry, oysters and some other seafood, fortified cereals, beans, nuts

Delicate Balance

When we eat too much of one vitamin or mineral, it can cause the loss of another. For instance, an excess of sodium will deplete calcium because these nutrients bind together, causing the body to excrete them both when it flushes out the sodium.

Getting Enough

In the U.S., nutrition deficiencies are relatively rare, although malnutrition is increasing, especially among older age groups. The most common deficiencies are of vitamin B 6 , iron and vitamin D. Of all the vitamins and minerals, Americans are least likely to be deficient in vitamin A, vitamin E and folate (B 9 ).

Beneficial combinations

Some nutrients work best as a team. Vitamin D helps us absorb calcium, for instance, and potassium encourages the excretion of excess sodium. Folate (B 9 ) is best absorbed if B 12 is around, and the two work together to help cells divide and multiply.

The recommended daily intake depends on age, sex, and many other factors. Dosage icons here are purposefully large to show the big-picture variation between different nutrients.

For more information: Dietary Supplement Fact Sheets, National Institutes of Health; Making Sense of Vitamins and Minerals, a special health report by the editors at Harvard Health Publishing in consultation with Howard D. Sesso, 2022.

Here’s how you know

• U.S. Department of Health and Human Services
• National Institutes of Health

Vitamins and Minerals

Vitamins and minerals are essential substances that our bodies need to function normally. The known vitamins are vitamins A, C, D, E, and K and the B vitamins: thiamin (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), cobalamin (B12), biotin, and folate/folic acid. A number of minerals are essential for health, including calcium, phosphorus, potassium, sodium, chloride, magnesium, iron, zinc, iodine, sulfur, cobalt, copper, fluoride, manganese, and selenium.  

• The Dietary Guidelines for Americans 2020–2025 recommends that people should aim to meet their nutritional requirements through a healthy eating pattern that includes nutrient-dense foods. In addition to vitamins and minerals, foods provide other important components beneficial to health, such as fiber. The guidelines provide recommendations for specific populations, including women who are or may become pregnant, women who breastfeed, and people ages 60 and over.  
• Some people who don’t get enough vitamins and minerals from food alone, including people who are on low-calorie diets or who avoid certain foods (such as strict vegetarians or vegans), may want to consider taking a vitamin and mineral supplement. Health care providers may recommend supplements for people with certain medical conditions.  

.header_greentext{color:green!important;font-size:24px!important;font-weight:500!important;}.header_bluetext{color:blue!important;font-size:18px!important;font-weight:500!important;}.header_redtext{color:red!important;font-size:28px!important;font-weight:500!important;}.header_darkred{color:#803d2f!important;font-size:28px!important;font-weight:500!important;}.header_purpletext{color:purple!important;font-size:31px!important;font-weight:500!important;}.header_yellowtext{color:yellow!important;font-size:20px!important;font-weight:500!important;}.header_blacktext{color:black!important;font-size:22px!important;font-weight:500!important;}.header_whitetext{color:white!important;font-size:22px!important;font-weight:500!important;}.header_darkred{color:#803d2f!important;}.Green_Header{color:green!important;font-size:24px!important;font-weight:500!important;}.Blue_Header{color:blue!important;font-size:18px!important;font-weight:500!important;}.Red_Header{color:red!important;font-size:28px!important;font-weight:500!important;}.Purple_Header{color:purple!important;font-size:31px!important;font-weight:500!important;}.Yellow_Header{color:yellow!important;font-size:20px!important;font-weight:500!important;}.Black_Header{color:black!important;font-size:22px!important;font-weight:500!important;}.White_Header{color:white!important;font-size:22px!important;font-weight:500!important;} Safety

• If you consume fortified foods and beverages (such as cereals or drinks with added vitamins and minerals) along with dietary supplements, you should make sure that your total intake of vitamins and minerals is not more than the safe upper limits for any nutrients. You can find information about the safe upper limits on specific nutrients from the NIH Office of Dietary Supplements Dietary Supplement Fact Sheets .  
• Taking excess amounts of vitamin A (preformed retinol form, not beta-carotene) during pregnancy has been shown to increase the risk of birth defects. 
• Women of childbearing age, pregnant women, infants, young children, and teenage girls are at risk of obtaining insufficient amounts of iron from their diets. Iron supplements are a leading cause of poisoning in young children, so they should be kept out of children’s reach. 

.header_greentext{color:green!important;font-size:24px!important;font-weight:500!important;}.header_bluetext{color:blue!important;font-size:18px!important;font-weight:500!important;}.header_redtext{color:red!important;font-size:28px!important;font-weight:500!important;}.header_darkred{color:#803d2f!important;font-size:28px!important;font-weight:500!important;}.header_purpletext{color:purple!important;font-size:31px!important;font-weight:500!important;}.header_yellowtext{color:yellow!important;font-size:20px!important;font-weight:500!important;}.header_blacktext{color:black!important;font-size:22px!important;font-weight:500!important;}.header_whitetext{color:white!important;font-size:22px!important;font-weight:500!important;}.header_darkred{color:#803d2f!important;}.Green_Header{color:green!important;font-size:24px!important;font-weight:500!important;}.Blue_Header{color:blue!important;font-size:18px!important;font-weight:500!important;}.Red_Header{color:red!important;font-size:28px!important;font-weight:500!important;}.Purple_Header{color:purple!important;font-size:31px!important;font-weight:500!important;}.Yellow_Header{color:yellow!important;font-size:20px!important;font-weight:500!important;}.Black_Header{color:black!important;font-size:22px!important;font-weight:500!important;}.White_Header{color:white!important;font-size:22px!important;font-weight:500!important;} What does the science say about multivitamin/multimineral supplements?

Multivitamins/multiminerals (MVMs) are popular dietary supplements taken by approximately one-third of adults and one-quarter of children and adolescents in the United States. MVMs cannot take the place of eating a variety of foods that are important to a healthy diet.  

Taking a daily dose of a basic MVM is unlikely to pose a health risk for healthy people. However, taking them at high doses or taking many different supplements may cause adverse side effects. 

• The effects of MVMs on the risk of health problems are hard to study because products vary and because people with healthier lifestyles are more likely to take MVMs. 
• Most studies have shown little or no effect of MVMs on the risk of health problems. 
• There’s no standard or regulatory definition for what nutrients MVMs, or any dietary supplement, must contain or at what levels. Manufacturers choose which vitamins, minerals, and other ingredients, as well as the amounts, to include in their products. However, MVMs are required to provide nutrition information on a Supplement Facts panel and list all ingredients on the product label (ingredients not in the Supplement Facts panel must be listed under “Other Ingredients”). 
• MVMs providing nutrients at or up to 100 percent of the Daily Value (DV) do not typically interact with medications. However, if you take a blood thinner, such as warfarin (Coumadin and other brand names), talk to your health care provider before taking any MVM or other dietary supplement that contains vitamin K . 
• Smokers, and possibly former smokers, should avoid MVM products that provide large amounts of vitamin A (as preformed retinol or beta-carotene or some combination of the two). A few studies have linked high supplemental doses of these nutrients with an increased risk of lung cancer in smokers. 
• The National Institutes of Health sponsored the Age-Related Eye Disease Study (AREDS), which showed that a dietary supplement formulation containing high doses of vitamins C and E, beta-carotene, zinc, and copper can help slow the progression to advanced age-related macular degeneration (AMD) . A second study, AREDS2, showed that removing beta-carotene from the AREDS formulation didn’t lessen its protective effect against developing advanced AMD. AREDS2 also showed that adding omega-3 fatty acids did not improve the effectiveness of the formulation. 

.header_greentext{color:green!important;font-size:24px!important;font-weight:500!important;}.header_bluetext{color:blue!important;font-size:18px!important;font-weight:500!important;}.header_redtext{color:red!important;font-size:28px!important;font-weight:500!important;}.header_darkred{color:#803d2f!important;font-size:28px!important;font-weight:500!important;}.header_purpletext{color:purple!important;font-size:31px!important;font-weight:500!important;}.header_yellowtext{color:yellow!important;font-size:20px!important;font-weight:500!important;}.header_blacktext{color:black!important;font-size:22px!important;font-weight:500!important;}.header_whitetext{color:white!important;font-size:22px!important;font-weight:500!important;}.header_darkred{color:#803d2f!important;}.Green_Header{color:green!important;font-size:24px!important;font-weight:500!important;}.Blue_Header{color:blue!important;font-size:18px!important;font-weight:500!important;}.Red_Header{color:red!important;font-size:28px!important;font-weight:500!important;}.Purple_Header{color:purple!important;font-size:31px!important;font-weight:500!important;}.Yellow_Header{color:yellow!important;font-size:20px!important;font-weight:500!important;}.Black_Header{color:black!important;font-size:22px!important;font-weight:500!important;}.White_Header{color:white!important;font-size:22px!important;font-weight:500!important;} What does the science say about taking vitamins and minerals to prevent or treat COVID-19?

There is not enough scientific evidence to clearly show that taking any dietary supplement helps to prevent or cure COVID-19 . The NIH Office of Dietary Supplements has detailed information (in English and Spanish ) about specific dietary supplements and COVID-19. 

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• Published: 18 June 2021

Vitamins and supplements - why choice and context are key

• Kimberley Lloyd-Rees 1  

BDJ Team volume  8 ,  pages 14–15 ( 2021 ) Cite this article

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By Kimberley Lloyd-Rees on behalf of Tandex

©David Malan/Stone/Getty Images Plus

At the end of 2020, the vitamin and supplement market was set to reach nearly £500 million in the UK, a record rise in value of around 9% on the previous year. 1 The biggest rise was for vitamin D, which will come as no surprise, after it was repeatedly linked with the prevention and management of COVID-19. Although some benefits from taking vitamin D are 'to optimise musculoskeletal health', the evidence in relation to the coronavirus remains 'indirect and inconclusive' and last December NICE, Public Health England and the Scientific Advisory Committee on Nutrition issued joint guidelines for healthcare practitioners on this matter. 2 , 3 Current government advice suggests taking a vitamin D supplement between October and March, with different recommendations for groups that could be deficient all year round, also for babies and young children. 4

The issue of choice

The vitamin D question aside, people are choosing to spend more money on protecting their health. But, if eating a healthy balanced diet, aside from certain exceptions, do most people need them? The answer is usually no from a clinical point of view and, if taken incorrectly and not according to the manufacturer's instructions, some vitamins and supplements might even be harmful. 5 Also, as the body can't store water-soluble vitamins such as B and C, any excess, as well as any money spent on these products, will end up down the toilet, literally. 6

The link between vitamin C and gingival health has long been known; patients deficient in vitamin C are more likely to develop gingivitis and present with gingival bleeding. But research now suggests a significant link between vitamin D and oral health. A recent study showed a link between vitamin D deficiency and a variety of oral health disorders, particularly in children. These include increased risk of and onset of the progression of dental caries, higher prevalence of periodontitis and, in some cases, oral cancers. 7 A connection can also be found between vitamin A and the regulation of salivary secretions, meaning patients lacking in vitamin A could be at higher risk of caries and gum disease due to xerostomia.

Research suggests that, for the most part, it is more beneficial to acquire these essential vitamins and minerals through dietary means. During your oral health consultations, diet and nutrition must be discussed. If the conversation turns to vitamins and supplements, and your patient is not in one of the groups for whom they are strongly advised, ensure you have plenty of resources on hand.

Diet and nutrition must be discussed [with patients]. If the conversation turns to vitamins and supplements, ensure you have plenty of resources

We have to consider the issue of choice. For example, if an individual is interested in their health and wellbeing, they adhere to good preventive behaviours and have done their research, choosing to take a high-quality daily multivitamin is no cause for concern. The bigger picture here is that they want to protect themselves against future illness. We're in the second year of the pandemic and people feeling motivated to take control of their health is one - perhaps the only - positive to come out of this time.

The context of poor nutrition

We must also look at the context of long-term concerns about poor diets in the UK. Despite ongoing public health campaigns, the data for childhood and adult obesity, including hospital admissions where obesity was a factor, show a continued increase, year-on-year, particularly in deprived areas. 8

Better nutrition means better health. It stabilises mood and improves immunity. 9 Plenty of everyday foods are nutrient rich and, when part of a balanced diet, will give your patients what they need without having to take a supplement (unless there is a recommendation that they do).

A healthy diet is not boring. The typical Mediterranean diet - which includes fruit, vegetables and wholegrain cereals, also moderate amounts of animal/fish protein and unsaturated fats - doesn't exclude the odd sweet treat or glass of something alcoholic and yet it is widely endorsed as the best way of eating to prevent disease, and even enjoy better mental wellbeing. 10 , 11

A common sense approach

If people are choosing to take vitamins and supplements, this should be part of a common-sense approach to preventive health, alongside other proven practices. These include eating a balanced diet, daily exercise, drinking in moderation, avoiding tobacco and having an effective oral hygiene routine - TANDEX has daily toothbrushes, interdental brushes and other adjuncts that make this job simple.

The vitamins and supplement market is worth millions, and we must hope that this means more people than ever want to stay well. By helping our patients learn as much as they can about the role of nutrition in preventing disease, and the other simple lifestyle changes that they can make, we will achieve better engagement, which will ultimately lead to improved outcomes for oral and general health.

For more information on Tandex's range of products, visit https://tandex.dk/ .

Author information

Kimberley graduated from the University of Sheffield in 2010, where she now works as a clinical tutor in dental hygiene and therapy as well as working in practice. She has spent her career working across a variety of specialist private and mixed dental practices, for the Ministry of Defence and volunteering her time to a dental charity in Nepal.

Mintel Press Office. The Vitamin D Factor: Brits spend almost £500 million on vitamins and supplements. 23 October 2020. Available at: https://www.mintel.com/press-centre/beauty-and-personal-care/the-vitamin-d-factor-brits-spend-almost-500-million-on-vitamins-and-supplements (accessed March 2021).

Vimaleswaran K S, Forouhi N G, Khunti K. Vitamin D and covid-19. BMJ 2021; 372: n544.

NICE. COVID-19 rapid guideline: vitamin D. NICE guideline [NG187]. 17 December 2020. Available at: https://www.nice.org.uk/guidance/ng187 (accessed March 2021).

NHS. Vitamin D. Available at: https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/ (accessed March 2021).

NHS. Do I need vitamin supplements? Available at: https://www.nhs.uk/common-health-questions/food-and-diet/do-i-need-vitamin-supplements/ (accessed March 2021).

BDA. The Association of UK Dietitians. Supplements: Food Fact Sheet. Available at: https://www.bda.uk.com/resource/supplements.html (accessed March 2021).

Botelho J, Machado V, Proença L, Delgado A S, Mendes J J. Vitamin D deficiency and oral health: a comprehensive review. Nutrients 2020; 12: 1471. doi: 10.3390/nu12051471.

NHS Digital. Statistics on Obesity, Physical Activity and Diet, England, 2020. 5 May 2020. Available at: https://digital.nhs.uk/data-and-information/publications/statistical/statistics-on-obesity-physical-activity-and-diet/england-2020 (accessed March 2021).

Chandra R K. Nutrition and the immune system from birth to old age. Eur J Clin Nutr 2002; 56: S73-76.

BBC. Ultra-processed food linked to early death. 30 May 2019. Available at: https://www.bbc.co.uk/news/health-48446924 (accessed March 2021).

Firth J, Gangwisch J E, Borisini A, Wootton R E, Mayer E A. Food and mood: how do diet and nutrition affect mental wellbeing? BMJ 2020; 369: m2382. doi: 10.1136/bmj.m2382.

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Lloyd-Rees, K. Vitamins and supplements - why choice and context are key. BDJ Team 8 , 14–15 (2021). https://doi.org/10.1038/s41407-021-0644-6

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• v.3(3); 2012 Mar

Vitamin and Mineral Supplements: Do We Really Need Them?

Farin kamangar.

1 Department of Public Health Analysis, School of Community Health and Policy, Morgan State University, Baltimore, MD, USA

2 Digestive Disease Research Center, Tehran University of Medical Sciences, Tehran, Iran,

Ashkan Emadi

3 Department of Medicine, Division of Hematology, John Hopkins School of Medicine, Baltimore, MD, USA,

In the United States, 40 – 50% of the men and women 50 years of age or older regularly use multivitamin/mineral (MVM) supplements, making the annual sales of these supplements over $11 billion. However, the question remains whether using MVM supplements is beneficial to health. This article reviews the results of randomized studies of MVM supplements and individual vitamins/mineral supplements in relation to overall mortality and incidence of chronic diseases, particularly cancer and ischemic heart disease. The results of large-scale randomized trials show that, for the majority of the population, there is no overall benefit from taking MVM supplements. Indeed, some studies have shown increased risk of cancers in relation to using certain vitamins.

INTRODUCTION

Multivitamin / mineral (MVM) supplements certainly sell well in the United States. According to the National Health and Nutrition Examination Survey (NHANES) data, collected between 2003 and 2006, 40 – 50% of the men and women 50 years of age or older regularly consume MVM 0supplements.[ 1 ] In 2009, the total sale of nutritional supplements in the United States was approximately $27 billion,[ 2 ] and in 2010, despite the economic downturn, this number grew by 4.4% to over $28 billion.[ 3 ] Of this, over $11 billion was the sales of MVM or MVM-containing supplements.[ 2 , 3 ] However, do healthy individuals really need MVM supplements? Are they beneficial in reducing the risk of chronic diseases such as ischemic heart disease, cancer, and stroke? The answer is most likely NO . The results of large-scale randomized trials in the past two decades have shown that for the majority of the population , MVM supplements are not only ineffective, but they may be deleterious to health.

When the Alpha-Tocopherol Beta-Carotene Cancer Prevention (ATBC) study presented the first strong evidence for a harmful effect of vitamins in 1994,[ 4 ] health scientists were caught by surprise. The results of this large-scale 2 × 2 factorial design trial, which randomized over 29,000 middle-aged Finnish smoker men to receive α-tocopherol (a form of vitamin E), beta-carotene (a precursor of vitamin A), both, or neither, showed that β-carotene statistically significantly increased lung cancer incidence by 18% and total mortality by 8%, mainly due to increased deaths from lung cancer and ischemic cardiac disease.[ 4 ] α-tocopherol did not materially change the risk of lung cancer or total deaths. Despite the strong design of this trial and its large sample size, the results were met with skepticism. The results were deemed to be inconsistent with several of the previously published observational studies, based on which the trial had been designed to reduce the risk of lung cancer.[ 5 , 6 ] Several of the accompanying letters of correspondence, published in the New England Journal of Medicine , pointed to the potential shortcomings of this study, such as short duration of the study (i.e., a median follow-up of six years). Nevertheless, results of most of the subsequent trials, using other forms of vitamins and supplements, conducted in different populations and with different durations of use, have confirmed no benefit or even harm from the use of such vitamin supplements [ Table 1 ].[ 4 , 7 – 17 ] The most recent notable one was the Selenium and Vitamin E Cancer Prevention Trial (SELECT Trial), the extended results of which showed that vitamin E supplements could increase the risk of prostate cancer among healthy men.[ 17 ] One exception to these null or deleterious effects was the result of the General Population Nutrition Intervention Trial conducted in Linxian, China,[ 7 , 18 ] which tested four combinations of vitamins and supplements (namely, factors A, B, C, and D). Factor D (a combination of selenium, α-tocopherol, and β-carotene) reduced overall mortality by approximately 10%. However, this trial was conducted in an area where micronutrient intake was quite poor, and thus supplements might have had a beneficial role. Even in this nutrition-deficient population, results of the trial showed no benefit for two of the other MVM supplements (factors B and C; see Table 1 ), and extended follow-up showed adverse results for one of the supplements (factor A containing zinc and vitamin A).[ 18 ]

Randomized, double-blind, placebo-controlled, primary prevention trials designed to reduce risk of major chronic diseases

Thus far, several meta-analyses, authoritative reviews, and expert panel reports have been published on the use of MVMs in preventing chronic diseases in healthy individuals. Almost all have found no overall benefit. For example, a systematic review and meta-analysis, published in the Journal of the American Medical Association (JAMA), in 2007, concluded that, “ Treatment with β-carotene, vitamin A, and vitamin E may increase mortality. The potential roles of vitamin C and selenium on mortality need further study ”.[ 19 ] Another more recent meta-analysis concluded that, “ Dietary supplementation with folic acid to lower homocysteine levels had no significant effects within five years on cardiovascular events or on overall cancer or mortality in the populations studied ” .[ 20 ] A recent re-analysis of the Women's Health Initiative, which was published along with the meta-analysis of the available literature, concluded that calcium supplements with or without vitamin D increased the risk of the cardiovascular events, particularly myocardial infarction.[ 21 ] An expert panel meeting at the National Institutes of Health, in 2006, concluded that there was ‘ insufficient evidence ’ to recommend for or against the use of MVMs by the American public to prevent chronic diseases.[ 22 ] The World Cancer Research Fund and the American Institute for Cancer Research has recommended against the use of dietary supplements by the public, for cancer prevention.[ 23 ] These expert panel reports appeared prior to the publication of the recent results from the SELECT Trial or those from the Women's Health Initiative, which bolstered the ‘ no benefit or even harm ’ conclusion.

We would like to emphasize that these conclusions are for the general population , and for prevention of chronic diseases such as cancer and cardiovascular disease. In special cases, individuals may need vitamins or supplements. For example, periconceptional folate supplements substantially reduce the risk of neural tube defects.[ 24 ] Likewise, iron supplements during pregnancy can substantially reduce the risk of anemia and perinatal complications in mothers.[ 25 ] Physician-recommended treatment of disorders such as osteoporosis,[ 26 ] as well as other diseases, may require use of MVMs or individual vitamins or minerals, but these are not the subject of this article. In addition, these conclusions do not negate the potential health benefits of eating fresh fruits and vegetables.

One might ask then, given substantial evidence for lack of any health benefit from MVM use for the majority of the adult population, why are these products so widely marketed in the United States and elsewhere? Or why would over 40% of the older population of the United States regularly use them? The answer is perhaps multifactorial. First, the belief in the use of vitamins has deep roots. The immense beneficial effects of vitamins in preventing pellagra, rickets, and scurvy at a period when overt nutritional deficiencies were common, gave the halo of a magical effect to these drugs. Before the 1990s, some eminent scientists strongly advocated the use of vitamins and supplements. Most notably, Linus Pauling, a two-time Nobel Laureate and a towering figure in chemistry, believed that vitamin C could prevent cancer and increase the life expectancy of cancer patients.[ 27 ] Pauling and Cameron supplemented 100 terminal cancer patients with vitamin C and compared them with 1000 similar patients who did not receive such supplementation and concluded that the lives of those receiving vitamin C were prolonged by one year.[ 28 ] However, this study was not randomized, and two subsequent double-blind randomized trials sponsored by the National Cancer Institute and conducted in the Mayo Clinic, did not find any benefit from oral supplementation with vitamin C.[ 29 , 30 ] Despite such negative results, the effect of Pauling's and other scientists’ highly publicized comments still linger in the media and in people's minds.

Second, in the United States, unlike the case for drugs, human research is not required to prove that supplements are safe or effective.[ 31 ] Only if the Food and Drug Administration (FDA) finds that supplements are unsafe, can they stop the distribution of the products.[ 31 ] Third, there exists substantial inaccurate or misleading advertising in the media, which might be expected, given the annual $27 billion business. For example, a TV commercial has advertised the use of a certain brand of MVMs based on the results of a ‘Harvard Study,’ which had shown that lycopene use may reduce risk of prostate cancer. Although a Harvard Study’ has indeed shown an inverse association between dietary lycopene intake and prostate cancer risk,[ 32 ] the inference that one must use MVMs is incorrect for various reasons: (a) MVMs contain many vitamins and elements other than lycopene; (b) the results had come from an observational study and not a randomized trial, hence the results are subject to confounding factors; (c) prostate cancer is not the only meaningful health outcome, and the overall effect of MVMs on health needs to be considered. Fourth, many believe that MVMs, if not useful, will not harm. As the results of ATBC have shown, such a belief may be false. Fifth, many people want to take an active role in improving their health and increasing their longevity. Avoiding tasty, but unhealthy food, may be difficult, but taking a pill once a day is relatively easy. As others have discussed, prescription is more convenient than proscription.[ 5 , 33 ]

In summary, although in the long run MVMs may slightly increase the risk of cancer and cardiovascular diseases, in the short run they produce little harm or no harm, and thus negative consequences will not be discernible by individuals taking them. MVM sales benefit from misleading commercials, and people are pleased by the well-known placebo effects. Therefore, Americans who have been using MVMs since the early 1940s,[ 22 ] will most likely continue to use them in the foreseeable future, and the rest of the world will follow.

Source of Support: Nil

Conflict of Interest: None declared.

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Can multivitamins improve memory a new study shows 'intriguing' results.

Allison Aubrey

The brain requires a large number of nutrients for optimal health and efficiency, but micronutrients are typically absorbed better through foods than through supplements. Grace Cary/Getty Images hide caption

The brain requires a large number of nutrients for optimal health and efficiency, but micronutrients are typically absorbed better through foods than through supplements.

Americans spend billions of dollars on supplements each year, and roughly 1 in 3 adults report taking a multivitamin. But there is a debate about whether this helps promote good health.

A team of researchers wanted to assess how a daily multivitamin may influence cognitive aging and memory. They tracked about 3,500 older adults who were enrolled in a randomized controlled trial. One group of participants took a placebo, and another group took a Silver Centrum multivitamin, for three years. The participants also took tests, administered online, to evaluate memory.

At the end of the first year, people taking a multivitamin showed improvements in the ability to recall words. Participants were given lists of words — some related, some not — and asked to remember as many as possible. (List-learning tests assess a person's ability to store and retrieve information.)

People taking the multivitamin were able to recall about a quarter more words, which translates into remembering just a few more words, compared to the placebo group.

"We estimate that the effect of the multivitamin intervention improved memory performance above placebo by the equivalent of 3.1 years of age-related memory change," the authors write in their paper, which was published this week in the American Journal of Clinical Nutrition . And the authors point to a sustained benefit.

"This is intriguing," says Dr. Jeffrey Linder, chief of general internal medicine at Northwestern University Feinberg School of Medicine, who was not involved in the study. But he says the overall effect found in the study was quite small. "It seems like a pretty modest difference," Linder says. And he points out that the multivitamins had no effect on other areas of cognition evaluated in the study, such as executive function, which may be more important measures.

Study author Dr. JoAnn Manson , who is chief of the division of preventive medicine at Brigham and Women's Hospital, says this is not the first study to show benefits from multivitamins. She points to a study published last year in Alzheimer's & Dementia that showed participants who took a daily multivitamin performed better, overall, on global cognitive function on tests measuring story recall, verbal fluency, digit ordering, as well as executive function.

"It is surprising that such a clear signal for benefit in slowing age-related memory loss and cognitive decline was found in the study, " Manson says. "Those receiving the multivitamin did better than those receiving the placebo."

Your Multivitamin Won't Save You

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Our bodies respond differently to food. a new study aims to find out how.

Our bodies and brains require many nutrients for optimal health and efficiency. Manson says if people have deficiencies in these nutrients it may influence memory loss or speed cognitive decline. So, she says taking a multivitamin may help someone prevent a deficiency if they're not getting all the nutrients they need from their diet.

"It's important to highlight that a multivitamin will never be a substitute for a healthy diet," Manson says, since micronutrients are typically better absorbed through foods than through supplements." But it may be a complementary approach or strategy for maintaining cognitive health among older adults," she says.

Linder says he will continue to tell his patients that if they eat a healthy diet they are unlikely to benefit much from a multivitamin. "If you're taking too much of a particular supplement and your body doesn't need it, you're just peeing it out," he says. He wrote an editorial, published in JAMA, arguing that vitamins and supplements could be a waste of money for a lot of people. He argues that we should help people adopt a better pattern of eating.

"Eating a diet that has plenty of fruits and vegetables is associated with longevity and better function and better quality of life," Linder says. There's plenty of research to show a healthy diet is linked to better heart health, and when it comes to protecting cognitive function, "the current thinking is that all of the stuff that's good for your heart is also good for your brain," he says.

When Linder talks to his patients about healthy aging, he focuses on good sleep habits, physical activity and a healthy diet. "My big concern with all of the focus that people have on vitamins is that it's distracting them from things that actually will help them stay healthy," Linder says.

"If someone is taking a multivitamin, I'm not going to tell them to stop," says Dr. R. Sean Morrison , who is a geriatrician at Mount Sinai Health System in New York. But he says he would not encourage the use of multivitamins as a way to protect against memory loss, because he says the effects measured in the studies are not very convincing. "I don't think it's the magic bullet that people are looking for," Morrison says. When talking to his patients, he too focuses on the importance of healthy habits and good social relationships.

The study was funded, in part, by the National Institutes of Health and other grants. The vitamins were provided by Pfizer Inc. and Haleon, the makers of Centrum, the brand of multivitamins taken by participants in the study. The study authors say the funders had "no role" in the study design, analysis or interpretation.

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Is There Really Any Benefit to Multivitamins?

Half of all American adults—including 70 percent of those age 65 and older—take a multivitamin or another vitamin or mineral supplement regularly. The total price tag exceeds $12 billion per year—money that Johns Hopkins nutrition experts say might be better spent on nutrient-packed foods like fruit, vegetables, whole grains and low-fat dairy products.

In an editorial in the journal Annals of Internal Medicine titled “Enough Is Enough: Stop Wasting Money on Vitamin and Mineral Supplements,” Johns Hopkins researchers reviewed evidence about supplements, including three very recent studies:

• An analysis of research involving 450,000 people, which found that  multivitamins did not reduce risk for  heart disease  or cancer .
• A study that tracked the mental functioning and multivitamin use of 5,947 men for 12 years found that  multivitamins did not reduce risk for mental declines  such as memory loss or slowed-down thinking.
• A study of 1,708 heart attack survivors who took a high-dose multivitamin or placebo for up to 55 months.  Rates of later  heart attacks , heart surgeries and deaths were similar  in the two groups.

Will a Daily Vitamin Help Keep Your Heart Healthy?

Is a daily vitamin necessary? Get the answer from Johns Hopkins physician Edgar Miller III.

The Vitamin Verdict

The researchers concluded that multivitamins don’t reduce the risk for heart disease, cancer, cognitive decline (such as memory loss and slowed-down thinking) or an early death. They also noted that in prior studies, vitamin E and beta-carotene supplements appear to be harmful, especially at high doses.

“Pills are not a shortcut to better health and the prevention of chronic diseases,” says  Larry Appel, M.D. , director of the Johns Hopkins Welch Center for Prevention, Epidemiology and Clinical Research. “Other nutrition recommendations have much stronger evidence of benefits—eating a healthy diet, maintaining a healthy weight, and reducing the amount of saturated fat, trans fat, sodium and sugar you eat.”

The exception is supplemental folic acid for women of child-bearing potential, Appel says. “Folic acid prevents neural tube defects in babies when women take it before and during early pregnancy. That’s why multivitamins are recommended for young women.” The Centers for Disease Control and Prevention recommends that all women of reproductive age get 400 micrograms of folic acid daily. The amount of iron in a multivitamin may also be beneficial for women of child-bearing potential, Appel adds.

“I don’t recommend other supplements,” Appel says. “If you follow a healthy diet, you can get all of the vitamins and minerals you need from food.”

What the Experts Do Healthy Food Instead of Supplements

“I don’t take any supplements routinely,” says Larry Appel, M.D. , director of the Johns Hopkins Welch Center for Prevention, Epidemiology and Clinical Research. “I try to eat three healthy meals a day to get the vitamins, minerals and other nutrients I need.” How he does it:

• Plenty of produce . “I aim for two or more servings of fruits or vegetables at every meal,” he says. “I enjoy salads and have one for lunch or dinner several times a week.”
• Low-fat dairy and whole grains . “Low-fat or fat-free milk and yogurt provide calcium, magnesium, potassium and other nutrients,” he says. “I have cereal with milk for breakfast a few times a week. And I have yogurt sometimes too.”
• Protein . “At home we usually have fish or chicken for dinner. I am not a vegetarian; rather, I eat minimal meat,” Appel says. Some fish, such as salmon, are a good source of healthful omega-3 fatty acids.

Definitions

Whole grains : Grains such as whole wheat, brown rice and barley still have their fiber-rich outer shell, called the bran, and inner germ. It provides vitamins, minerals and good fats. Choosing whole grain side dishes, cereals, breads and more may lower the risk for heart disease, type 2 diabetes and cancer and improve digestion, too.

Saturated fat : A type of fat found in abundance in butter, whole milk, ice cream, full-fat cheese, fatty meats, poultry skin, and palm and coconut oils. Saturated fat raises levels of heart-threatening LDL cholesterol in your bloodstream. It can also interfere with your body’s ability to absorb blood sugar easily. Limiting saturated fat can help control your risk for heart disease.

Omega-3 fatty acids (oh-may-ga three fah-tee a-sids) : Healthy polyunsaturated fats that the body uses to build brain-cell membranes. They’re considered essential fats because our body needs them but can’t make them on its own; we must take them in through food or supplements. A diet rich in omega-3s—found in fatty fish, like salmon, tuna and mackerel, as well as in walnuts, flaxseed and canola oil—and low in saturated fats may help protect against heart disease, stroke, cancer and inflammatory bowel disease.

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Health effects of vitamin and mineral supplements

Read our food for thought 2020 collection.

• Related content
• Peer review
• Fang Fang Zhang , associate professor 1 ,
• Susan I Barr , professor 2 ,
• Helene McNulty , professor 3 ,
• Duo Li , professor 4 ,
• Jeffrey B Blumberg , professor 1
• 1 Friedman School of Nutrition Science and Policy, Tufts University, Boston, USA
• 2 University of British Columbia, Vancouver, Canada
• 3 Nutrition Innovation Centre for Food and Health, Ulster University, Coleraine, UK
• 4 Institute of Nutrition and Health, Qingdao University, Qingdao, China
• Correspondence to: F F Zhang fang_fang.zhang{at}tufts.edu

Growing numbers of healthy people are taking dietary supplements but there is little evidence that they protect against non-communicable diseases, say Fang Fang Zhang and colleagues

Vitamin and mineral supplements are the most commonly used dietary supplements by populations worldwide. 1 2 3 4 The amount of micronutrients they provide ranges from less than recommended intakes to much more, making them important contributors to total intakes. While supplements can be used to correct micronutrient deficiency or maintain an adequate intake, over-the-counter supplements are most often taken by people with no clinical signs or symptoms of deficiency. However, the effect of vitamin and mineral supplements on the risk of non-communicable diseases in “generally healthy” populations is controversial. We examine patterns of supplement use and the evidence on their effects from randomised trials.

Who uses supplements?

Vitamin and mineral supplements have a large worldwide market, but we will focus on their use in North America and Europe, where there is most evidence on patterns of use and health outcomes. The use of vitamin, mineral, and fish oil supplements 5 is common among adults in North America ( fig 1 ). 6 The prevalence of use has increased for some individual nutrients—for example, there was a fourfold increase in use of vitamin D supplements among US adults from 1999 to 2012, excluding intake obtained from multivitamin and mineral. 7 The use of omega-3 fatty acid supplements also increased sevenfold. 7

Proportion of US adults taking commonly vitamin, mineral, and fish oil supplements, National Health and Nutrition Examination Survey 1999-2014 6

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Supplement use is generally less prevalent in other countries than in the US and Canada but varies widely (eg, Denmark 51%, South Korea 34%, Australia 43%, UK 36%, Spain 6%, Greece 2%). 2 3 4 Different methods for assessing supplement use may contribute to the different prevalence in high income countries. National survey data for supplement use in the general population remain scarce for low and middle income countries.

Supplement use varies considerably among population subgroups within North America and Europe. In the US, >70% of adults aged ≥65 years use supplements 8 compared with a third of children and adolescents. 9 More women than men use supplements. 6 Supplement use correlates positively with educational and socioeconomic status. 10 It also clusters with healthy lifestyle factors such as not being a smoker or heavy drinker, not being overweight or obese, and being physically active. 6 Importantly, people who use supplements tend to have a better overall diet quality than those who don’t use them and their nutrient intake from foods mostly meets recommended intake levels. 11 12

Are supplements needed?

Use of supplements contributes substantially to total vitamin and mineral intakes at the population level. 13 Intake of vitamin B 6 , thiamin, and riboflavin among US adults is at least five times higher from supplements than from foods, and intakes are 15 to 20 times higher for supplements for vitamins B 12 and E. 6 Consequently, supplement use considerably reduces the proportion of the general population with inadequate nutrient intake ( box 1 ).

Population nutrient intake—definitions

Estimated average requirement is the daily level of nutrient intake estimated to meet the requirement of half of healthy people in a population

Inadequate nutrient intake —The population prevalence of inadequate intake is estimated as the percentage of the population with nutrient intake below the estimated average requirement

Tolerable upper intake is the highest daily nutrient intake that is likely to pose no risk of adverse health effects to almost all healthy people in a population. As intake increases above the upper level, the potential risk of adverse effects increases.

Excess intake —The population prevalence of excess intake is estimated as the percentage of the population with nutrient intake above the upper level

This is especially true for vitamins and minerals identified as “shortfall” nutrients such as calcium and vitamin D ( fig 2 ). 14 Despite the high use of supplements, inadequate intakes of micronutrients are still common in high income countries, where dietary patterns are typically energy rich but nutrient poor.

Prevalence of inadequate and excess nutrient intake among US Adults, National Health and Nutrition Examination Survey 1999-2014 6

In low and middle income countries, where specific micronutrient deficiencies are prevalent (eg, of iodine, iron, zinc, and vitamin A), supplementation is recommended when food based approaches such as dietary modification, fortification, or food provision are unable to achieve inadequate intake. 15 In the US and other countries, food fortification and enrichment such as the addition of iodine to salt, vitamin D to milk, and B 1 and B 3 vitamins to refined flour have contributed to the virtual elimination of their syndromes of deficiency (goitre, rickets, beriberi, and pellagra, respectively). 16 17

The widespread use of vitamin and mineral supplements in high income countries seems to contribute to an increase in population prevalence of intake above the upper tolerable level ( box 1 ). 6 Although the overall proportion of US adults with intakes above the upper level is below 5% for most nutrients ( fig 2 ), some population subgroups may have high rates of excess intake. For example, in a Canadian national survey, over 80% of children aged 1-3 years who took dietary supplements consumed vitamin A and niacin at levels above the upper limit. 18 In the US, excessive intake was noted for vitamin A (97%) and zinc (68%) among toddlers who were given supplements. 19 High quality evidence is lacking on the long term adverse effects of excess intake for several nutrients so it is unclear whether this is a cause for concern.

Do supplements protect against non-communicable diseases?

It remains controversial whether supplements are effective in reducing the risk of non-communicable diseases. In contrast to results of observational studies, the accumulated evidence from randomised controlled trials does not support benefits of supplements in reducing risks of cardiovascular disease, cancer, or type 2 diabetes in healthy people with no clinical nutritional deficiencies.

Cardiovascular disease

An updated systematic review of 15 randomised trials published after the 2013 US Preventive Service Task Force (USPSTF) review 20 confirmed the lack of benefits of supplements on cardiovascular events, mostly among patients with risk factors. 21 Although randomised trials of folic acid, alone or in combination with vitamins B 12 or B 6 , found significant reductions in plasma homocysteine levels, total cardiovascular events were not reduced. Another systematic review reported a reduced risk of stroke in association with supplementation of homocysteine lowering B vitamins, 22 but the result was largely driven by one large trial in China. 23 Overall, there is no consistent evidence to support the use of antioxidant supplements for reducing cardiovascular risk. 22 24

The Vitamin D and Omega-3 Trial (VITAL), one of the few randomised trials of supplements for primary prevention of cardiovascular disease, found no effect of vitamin D supplementation (2000 IU/day) on its primary endpoint (myocardial infarction, stroke, or cardiovascular death) in healthy people. 25 Previous large scale trials such as the Women’s Health Initiative Calcium and Vitamin D Supplementation Study 26 and the Vitamin D Assessment Study 27 also showed vitamin D supplements, alone or in combination with calcium, had no effect on cardiovascular risk.

Supplementation with omega-3 fatty acids (1 g/day) did not reduce the risk of major cardiovascular events among healthy people in the VITAL trial. 28 However, benefits were found for some secondary endpoints such as total myocardial infarctions. This result is largely consistent with findings from meta-analyses that fish oil supplementation did not have substantial effects on the primary or secondary prevention of cardiovascular disease. 29 30 However, a meta-analysis including the most recent trials reported a significant reduction in risk of myocardial infarction. 31 Further studies are needed to determine whether fish oil supplementation has a greater effect on risk of heart disease than of stroke. 32

Current evidence does not support a role of vitamin and mineral supplements in reducing cancer risk, with some evidence suggesting potential harm. β-Carotene supplementation increased the risk of lung cancer among high risk individuals in two randomised trials. The α-Tocopherol, β-Carotene Cancer Prevention Study reported an 18% increase in relative risk among smokers randomised to β-carotene (20 mg/day) compared with those who did not. 33 The β-Carotene and Retinol Efficacy Trial found that β-carotene (30 mg/day) plus vitamin A as retinol (25 000 IU/day) increased risk by 28% among smokers and workers with occupational exposure to asbestos. 34 The Selenium and Vitamin E Cancer Prevention Trial found that vitamin E (400 IU/day) supplementation was associated with a 17% increase in prostate cancer risk among men. 35

Although maternal folic acid supplementation has been proved to reduce the risk of neural tube defects, concerns have been raised that high folic acid exposure may promote cancer progression, especially in countries with mandatory fortification. 36 Most notably, folic acid supplementation at ≥1 mg/day may promote the growth of undiagnosed colorectal adenomas. 37 However, a meta-analysis of 11 randomised trials concluded that folic acid supplementation neither increased nor decreased site specific cancer risk within the first five years of supplementation. 38

Randomised trials have failed to detect a benefit of vitamin D supplementation, alone or combined with calcium, on cancer risk at either high or low doses 25 39 despite some evidence suggesting reduced total cancer mortality. 25 40 The limited evidence on fish oil supplementation suggests it does not reduce cancer risk. 28 41

Type 2 diabetes

Current evidence does not support the use of supplements with vitamins C or E, β-carotene, or fish oil to reduce the risk of type 2 diabetes, although the overall evidence from randomised trials is limited. 42 43 A recent placebo controlled trial of vitamin D supplementation (4000 IU/day) failed to reduce the risk of type 2 diabetes despite significantly increasing serum 25-hydroxyvitamin D concentrations. 44

Osteoporosis

Recent evidence regarding the effects of vitamin D and calcium supplementation is inconsistent. A meta-analysis of trials in community living older adults found that vitamin D or calcium supplementation did not reduce the risk of hip fracture or total fracture, 45 whereas another meta-analysis reported that while vitamin D alone did not reduce fracture risk, combined calcium and vitamin D supplementation decreased the relative risk of hip fracture (16%) and all fractures (6%) among older adults. 46 Ongoing research is assessing the effect of high dose vitamin D supplements on several health outcomes, including fractures, 46 but a recent three year trial of 400, 4000, or 10 000 IU/day reported that the higher doses reduced volumetric bone density, suggesting potential for harm. 47 In the absence of clear evidence on supplementation, it is prudent to ensure that dietary recommendations on calcium and vitamin D intakes are met through food and supplementation.

To date, randomised trials have largely shown no benefit of vitamin, mineral, and fish oil supplements on the risk of major non-communicable diseases in people without clinical nutritional deficiency. These results contrast with findings from observational studies, where supplemental nutrient intakes are often associated with a reduced risk of these diseases. The apparent associations from observational studies may result from unknown or unmeasured confounding factors such as socioeconomic status and lifestyle factors, including a better overall diet.

Although randomisation reduces confounding, relying exclusively on the results of randomised trials also has limitations. Trials are often conducted among high risk populations with pre-existing conditions, so the findings may not be applicable to healthy individuals. Supplements may also have health benefits for population subgroups, such as people with inadequate nutrient intake from foods, but randomised trials are not usually designed to evaluate subgroup differences. Furthermore, financial and practical constraints mean that most trials are able to investigate only a single dose, which may result in selection of a dose that is either too low (no efficacy) or too high (untoward outcomes).

Nutrients obtained from foods and supplements may confer different health effects. The Cancer Prevention Study (CPS)-II Nutrition Cohort found that supplemental calcium intake at ≥1000 mg/day was associated with an increased risk of all-cause mortality in men whereas high levels of calcium intake from foods had no harm. 48 Among US adults in the National Health and Nutrition Examination Survey, adequate intake of nutrients from foods, but not supplements, was associated with a lower risk of all-cause mortality. 6 The benefits of nutrient intake from foods may reflect synergistic interactions among multiple nutrients and other bioactive substances in foods.

The effect of supplements in specific populations warrants further investigation. Older adults are at an increased risk of malnutrition because of reduced nutrient intake and age related decreases in the bioavailability of some micronutrients. Vitamin D supplementation is recommended for breastfed infants before the introduction of whole milk and solid foods. Supplements may be more effective in reducing the risk of non-communicable disease in specific ethnic groups or people with low micronutrient intake from foods. 28 With a recent increase in the proportion of people reporting that they follow restricted dietary patterns such as ketogenic, Palaeolithic, vegan, and vegetarian diets, the value of supplements to meet the needs of these specific populations requires evaluation. In addition, potential nutrient-gene interactions have rarely been examined in studies of dietary supplements. Future studies on the role of nutrigenetics should help refine and personalise targeted recommendations for supplement use ( box 2 ).

Areas for research in vitamin and mineral supplementation

Differing health effects of nutrients obtained from foods versus supplements

Synergistic interactions among multiple nutrients and with other bioactive substances

Subpopulation studies (eg, elderly people, ethnic groups, vegans)

Nutrigenetics and “omics” sciences

Personalised supplementation

Specific needs in low and middle income countries

It is also important to recognise that the need for nutrient supplements is different in countries where nutrition deficiency is common. Ensuring adequate nutrition through food fortification and nutrient supplementation can be crucial to prevent serious adverse outcomes of nutrient deficiencies in low and middle income countries, especially among children <5 years, for whom malnutrition contributes to more than half their deaths. 15

In summary, current evidence does not support recommending vitamin or fish oil supplements to reduce the risk of non-communicable diseases among populations without clinical nutritional deficiency. Continuing efforts are warranted to further understand the potentially different roles of nutrients from foods versus supplements in health promotion among a generally healthy population as well as individuals or groups with specific nutritional needs, including those living in low and middle income countries. These efforts, coupled with the integration of new research approaches, will better inform clinical practice and public health policies.

Key messages

Randomised trial evidence does not support use of vitamin, mineral, and fish oil supplements to reduce the risk of non-communicable diseases

People using supplements tend to be older, female, and have higher education, income, and healthier lifestyles than people who do not use them

Use of supplements appreciably reduces the prevalence of inadequate intake for most nutrients but also increases the prevalence of excess intake for some nutrients

Further research is needed to assess the long term effects of supplements on the health of the general population and in individuals with specific nutritional needs, including those from low and middle income countries

Contributors and sources: All authors contributed to drafting the manuscript, with FFZ taking a lead role and serving as the guarantor. Sources of information for this manuscript included published articles based on national surveys, systematic reviews, and primary research of randomised controlled trials and prospective cohort studies. All authors contributed to critical revision of the manuscript for important intellectual content and approved the final manuscript.

Competing interests: All authors have read and understood BMJ policy on declaration of interests and declared the following: FFZ declares funding from the National Institutes of Health, NIMHD (R01 MD 011501) and the Bristol Mayer Squibb Foundation (Bridging Cancer Care Programme). DL declares funding from the National Natural Science Foundation of China (NSFC 81773433) and Key Scientific Research Projects in Shandong Providence China (2017YYSP007). JBB declares funding from Danone. HM declares funding from DSM Nutritional Products, Switzerland. The funders had no role in the design or conduct of the study, collection, management, analysis, or the interpretation of the data. JBB reports service on scientific advisory boards of AdvoCare International, California Prune Board, California Walnut Commission, Church and Dwight, Cranberry Marketing Committee, Guiding Stars, Quaker Oats, Segterra, and SmartyPants, not related to this work.

Provenance and peer review: Commissioned; externally peer reviewed.

This article is part of series commissioned by The BMJ. Open access fees are paid by Swiss Re, which had no input into the commissioning or peer review of the articles. T he BMJ thanks the series advisers, Nita Forouhi, Dariush Mozaffarian, and Anna Lartey for valuable advice and guiding selection of topics in the series.

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/ .

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Home > Books > Functional Food - Improve Health through Adequate Food

New Advances about the Effect of Vitamins on Human Health: Vitamins Supplements and Nutritional Aspects

Submitted: 10 November 2016 Reviewed: 11 April 2017 Published: 02 August 2017

DOI: 10.5772/intechopen.69122

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Functional Food - Improve Health through Adequate Food

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The early twentieth century was a crucial period for the identification and biological-chemical-physical characterisation of vitamins. From then until now, many studies have attempted to clarify into detail the biological role of the vitamins in humans and their direct connection with certain diseases, either in a negative way (appearance of deficiency diseases due to vitamin deficiency) or a positive way (use of vitamins to treat diseases and/or to improve human health). The aim of this work is to analyse, from an integrative point of view, the information about vitamins and their effects on human health, and to identify direct correlations between these compounds and health. The effects of vitamins supplements on diet are also explored. The analysis of the results shows that it is impossible to establish robust and universal conclusions about the benefit of vitamin supplementation on human health beyond the prevention and/or treatment of deficiency states.

• human health
• antioxidants
• dietary supplements
• multivitamins

Author Information

Noelia garcía uribe.

• Department of Agrochemistry and Biochemistry, Faculty of Science, Biochemistry and Molecular Biology, University of Alicante, Spain

Manuel Reig García-Galbis

• Department of Nursing, Faculty of Health Sciences, University of Alicante, Spain
• Department of Nutrition, Faculty of Health Sciences, University of Atacama, Chile

Rosa María Martínez Espinosa *

*Address all correspondence to: [email protected]

1. Introduction

Human nutrition, as a field of knowledge, had a great impact at the beginning of the twentieth century. From 1912, experiments such as those developed by English biochemist Frederick Hopkins (1861–1947) demonstrated the existence of certain organic substances in food that are essential for health. Hopkins called them ‘accessory food factors’ [ 1 – 3 ]. Shortly after that discoveries, the Polish biochemist Casimir Funk (1884–1967) proposed the term ‘vitamins’ to identify the substances previously termed ‘accessory food factors’ [ 2 , 3 ]. The etymology of the term vitamin derives from the Latin ‘vita’ (life) and ‘amina’; Funk concluded that these substances were necessary for life and most of them contained an amino group [ 1 , 4 ]. Thus, in the early sixties, the identification of essential nutrients necessary to support human life and health (macronutrients, micronutrients and trace elements) was almost concluded [ 4 ].

In the last half of last century, all vitamins were identified, their chemical structures were determined and natural sources from which vitamins can be obtained were described in detail. The biological role of each vitamin, their connections with several metabolic pathways and human pathologies and their importance in human nutritional processes were also quickly established [ 2 , 4 ]. Besides, advances in chemical analysis/technologies during the last three decades have provided the tools to produce vitamins in vitro (even at large scale). Consequently, vitamins can be currently obtained by chemical synthesis, by isolation of natural sources (fat-soluble vitamins) or by microbial biotechnology (mainly water-soluble vitamins).

Thus, several human pathologies based on vitamins deficiency can be fully eradicated or their prevalence decreases substantially thanks to (i) promotion of good nutrition practices and (ii) use of dietary supplements containing mainly vitamins and trace elements. Even so, malnutrition is still a massive problem, particularly in some geographic regions characterised by poverty, poor nutrition understanding and practices and deficient sanitation and food security.

During the last five decades, several scientific-technical reports have confirmed and/or suggested new biological roles and properties for vitamins in human beings. Despite a large amount of existing information, there are very few integrative studies carried out on the effect of the vitamins on human health. In this sense, the work here presented summarises the main recent evidences that provide an integrated and updated analysis about the effect of vitamins in human health. The main aim is to understand how the use of vitamins (from food or from dietary supplements containing vitamins) can improve human health or the evolution of some specific disease.

2. General aspects of vitamins

2.1. definition and classification.

Vitamins are organic micronutrients mainly synthesised by plants and microorganisms, which do not provide energy. Animals are not able to synthesise them, consequently, these essential micronutrients must be supplied by the diet in small amounts or even trace amounts (micrograms or milligrammes per day) for the maintenance of the metabolic functions of most animal cells [ 5 , 6 ]. However, some vitamins can be synthesised in varying concentrations by humans. Thus, vitamin D and niacin are endogenously synthesised (in the skin by exposure to the sun or from the amino acid tryptophan, respectively) [ 7 , 8 ]. On the other hand, vitamins such as K2, B1, B2 and biotin are synthesised by intestinal bacteria [ 9 ]. Generally, this endogenous synthesis is not enough to cover daily needs, so dietary intake is required [ 8 , 10 ]. Most of the vitamins were identified related to the diagnosis of the diseases associated with their deficiency [ 2 , 11 ]. Thus, these diseases are termed ‘deficiency diseases’.

Two groups of vitamins are distinguished based on their solubility (fat-soluble and water-soluble vitamins) [ 6 ] ( Table 1 ). Each of these two groups exhibit significantly different physical-chemical-biological characteristics. The alphabetic nomenclature indicates the chronology of its discovery; however, the subsequent observation that vitamin B consisted of multiple compounds, gave rise to numerical nomenclature. The gaps in numbering are due to the removal of several substances that were initially described as vitamins [ 8 , 10 ].

Table 1.

Classification and differences of vitamins based on their solubility [ 6 ].

Note. Underlined: Name mainly used in the scientific literature.

Besides, vitamins are also classified by their biological role, which constitutes a more scientific approach to the current reality (Section 2.3 display details about the biological roles).

2.2. Physical-chemical properties

Each vitamin is a family of chemically related compounds that share qualitatively biological activities and may vary in aspects related to their bioactivity and bio assimilation. Therefore, the common name of the vitamin (i.e. vitamin A) is, in fact, a generic descriptor for all active analogues or relevant vitamin derivatives [ 12 ]. Table 2 summarises the main physical-chemical properties.

Table 2.

Physic-chemical properties of vitamins and the most relevant derivatives (Adapted from Combs, [ 12 ]; https://www.ncbi.nlm.nih.gov/pccompound ; http://www.lipidbank.jp/ ).

2.3. Biological roles

Vitamins play an important role in several metabolic pathways, acting closely associated with many of the enzymes that catalyse the reactions involved in these metabolic processes [ 10 , 13 , 14 ].

Using the ‘biological role’ as criteria, vitamins are classified into five groups:

Vitamins acting as coenzymes: B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine) and B7 (biotin).

Antioxidant vitamins: E (α-tocopherol) and C (ascorbic acid).

Vitamins showing hormonal functions: A (retinol) and D (calciferol)

Vitamins that act in the cellular proliferation: B9 (Folic acid), B12 (cobalamin).

The vitamins involved in coagulation: K or phylloquinone.

Thus, vitamins belonging to the group B work together at the cellular level and they are essential for neurological functioning and central metabolism [ 15 ]. A deficient intake of one or more than one of them may hinder the use of the other vitamins of group B. On the other hand, antioxidant vitamins protect against cell damage caused by the oxidative attack of free radicals reactive nitrogen species (ROS), Reactive nitrogen species (RNS), avoiding the destruction of the body’s tissues. This group of vitamins prevent the development of a large number of degenerative diseases, associated with ageing and oxidative stress, such as Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, cancer and myocardial infarction (heart attack), among others [ 16 , 17 ]. In addition, some vitamins assume additional endocrine functions [ 18 ]. Consequently, the deficiency of a vitamin causes metabolic processes imbalances. This fact results in clinical signs or diseases of different health impact based on the level of deficiency. Table 3 summarises the main biological roles played by vitamins and anomalies in human health due to vitamin excess (toxic effects in the case of liposoluble vitamins) or vitamin deficiency.

Table 3.

Main biological functions, clinical signs of deficiency and toxic effects (caused by excessive intake, hypervitaminosis) of vitamins [ 8 , 10 , 14 , 18 – 20 ].

1 First nutritional deficiency described, typical of populations subsisting on diets in which polished (‘white’) rice is the major food. The pathology leads to weight loss, heart disorders and neurological dysfunction.

2 Affectation of the mucous membranes, tongue (glossitis), lips (cheilitis) and hypervascularization of the cornea.

3 In populations subsisting on diets in which maize is the major food.

4 Head and neck redness.

5 Signs and symptoms include: follicular hyperkeratosis, petechial, ecchymosis, coiled broken hairs, swollen and bleeding gums, perifollicular bleeding, joint spasm, arthralgia and altered wound healing (IOM, [ 18 ]; Combs, [ 10 ]).

NS: Nervous system; CNS: central nervous system; IGT: impaired glucose tolerance.

3. Recommended dietary intakes

Most foods (exceptions: sucrose, refined grains and alcoholic beverages), provide vitamins in number and variable quantity [ 6 ]. However, there is not a single food containing all of them. Therefore, the diets must be mixed and balanced thus supplying the vitamins at the levels required by the body. When a food (or a diet) provides some or all the macronutrients but does not contain the necessary vitamins, it hinders the correct metabolism. Consequently, several official institutions around the world provide guides to recommend the optimum values of daily vitamins intake to promote health and to eradicate deficiency diseases.

The reference values of vitamin intake, allow preventing deficiency states and hypervitaminosis. Table 4 shows the recommended dietary allowance (RDA) related to vitamins, which are focused on metabolic needs in the general population, and the maximum tolerable daily intake (UL) without risk of adverse health effects for the general population. These may vary between countries.

Table 4.

Recommended dietary allowances (RDAs), tolerable upper intake level (UL) for healthy adults and main food sources containing the vitamins described [ 18 ], https://fnic.nal.usda.gov/sites/fnic.nal.usda.gov/files/uploads/DRI_Vitamins.pdf ].

*RDAs for vitamins A and D are listed in both International Units (IUs) and micrograms (mg/day) or micrograms (µg/day). The hyphen (-) indicates that the UL is not determined due to lack of data on the adverse effects associated with the excessive intake of these vitamins.

1 The vitamin A activity in foods is thus currently expressed as retinol equivalents (RE): 1 RE is defined as 1 µg of all-trans retinol, 6 µg of all-trans β-carotene, or 12 µg of another provitamin A carotenoids. Or it is expressed in IU (international units): 1 IU of vitamin A activity has been defined as equal either to 0.30 µg of all-trans retinol or to 0.60 µg of all-trans β-carotene.

2 In the case of vitamin D, 1 μg calciferol = 40 IU of vitamin D, a value based on a minimum of sun exposure.

Some vitamins can be supplied as provitamins, substances without vitamin activity that when metabolised, give rise to the formation of the corresponding vitamin [ 8 , 12 ]. In some cases, it is possible to synthesise the vitamin from dietary compounds that apparently have no relation to it. For instance, nicotinic acid (vitamin B3) can be caused by the metabolic transformation of the amino acid tryptophan [ 8 ] or retinol (vitamin A), which can be obtained from beta-carotene (a pigment produced by some vegetables and microorganisms) [ 21 ].

4. Bibliographic and bibliometric analysis of the selected information.

To identify the main recent scientific-technical works about vitamins and their effect in human beings, a bibliographic/bibliometric review has been made following PRISMA guide [ 22 ]. The classical scheme proposed by Vilanova [ 23 ] has been used to analyse and to assess the quality of the information obtained. The main aim of this analysis is to understand how the use of vitamins (from food or from dietary supplements containing vitamins) can improve human health or the evolution of some specific diseases.

To do the information search (manuscripts published during the last 27 years in English and Spanish), general and more specific databases were selected ( https://scholar.google.es/ ; PubMed, http://www.ncbi.nlm.nih.gov/pubmed ; Scopus, https://www.scopus.com/ ; Web of Science (WOS), https://apps.webofknowledge.com/ ). The keywords used to do the search were: all the names of the vitamins, ‘vitamins & human health’, ‘vitamins & biological roles’ and ‘deficiency diseases’. These terms were previously identified through the database ‘MeSH’ (medical subject heading) as suitable descriptors for the realisation of this work. Combinations of these keywords with the terms ‘diet’ and ‘nutrition’ were also used to identify as many sources as possible. All the following options were selected in the databases previously mentioned: ‘Title/Abstract’, ‘article’, ‘clinical trial’ and ‘review’. Search finished in December 2016, the 15th. The research questions used to do the search and to select the information were: What is new about the knowledge of the effect of vitamins on human health? Is human health improving when multivitamin complexes are used?

Figure 1 displays the results of the search just using the combination ‘vitamins & human health’. Thanks to this keywords combination, 99,990 publications were identified (32,363 Pubmed; 35,127 WOS; 32,500 Scopus). About 60–77% of these publications are research articles (most of them clinical trials), 13–24% reviews and 5–11% are proceedings. Most of the items consulted (85%) belong to the field of medicine, followed by the fields of biochemistry, genetics and molecular biology (15%). To carry out this work, all the items were analysed by the three authors paying special attention to reviews and clinical trials. As it can be concluded from this figure, the last decade was particularly productive in terms of a number of publications analysing the effect of vitamins in human health or the use of vitamins as part of a treatment against certain pathologies.

Figure 1.

Identification of publications of interest. Number of items reported in the last 27 years. Keywords: Vitamins & Human health.

To address the detailed analysis of the direct effects of vitamins in human health, described by each item identified ( Figure 1 ), four categories or manuscripts were established: 1: experimental studies, clinical trials; 2: analytical observational studies (cohort studies; case-control studies); 3: Descriptive observational studies (series of cases; studies of incidence and prevalence); 4: Reviews, systematic reviews and/or meta-analysis. The main conclusions from this analysis are summarised in the following section.

5. New advances of the effect of the use of vitamins through the diet in human health as well as the treatment of several human diseases

From the database containing the publications of interest previously mentioned, 75% of them were analysed into detail to highlight what is new about the use of vitamins through the diet in human health as well as their use as part of the treatment of several human diseases. Most the publications analysed in this work suggest a possible effect of a vitamin (its derivatives, analogues or precursors), or combinations of vitamins in human health. However, the results presented in the majority these publications are not conclusive. Thus, most of them assume that it is not possible to attribute with certainty the effect observed due to inconsistencies in the design or implementation of the studies. In this sense, there are many aspects to discuss, which are following summarised:

The standard method of medical science to establish and to compare the effectiveness of a substance in human beings is the clinical trial [ 24 ]. However, despite having strict inclusion criteria, these studies present some features that can affect the results. Some of the main features that may influence the results are: genetic background and style of life of the patient; non-specific effects and bioavailability of the vitamin/molecule tested; selection of the mechanism of action of the molecule tested; validity of the biomarkers used to determine the effect of a compound; the sample size (population) and the duration of the study (especially critical when the pathological condition under study takes decades to develop). All these aspects should be taken into account when interpreting the clinical results; otherwise, the associations observed are inadequately estimated of causality, and consequently, a direct relationship between the administration of a vitamin and effect on human health cannot be properly established.

Observational studies are easier to perform in terms of methodology, but they lack the capacity to establish causality of phenomena.

The meta-analysis presents a high level of scientific evidence, especially the meta-analysis of randomised controlled trials [ 24 ]. Meta-analysis is characterised by the high size of the study population, and therefore, they show better clinical significance. However, as a disadvantage, they usually are not feasible due to the difficulties of finding trials with the homogeneous design.

Therefore, despite a large number of publications on the vitamins and the potential uses of multi/vitamin supplements, there is no scientific evidence of beneficial effects in human health, beyond the prevention and/or treatment of deficiency states.

In this sense, the supplementation of food, as well as strategies to improve nutritional practises, have contributed to the eradication of deficiency diseases [ 25 – 28 ]. The main biological functions, clinical signs of deficiency and toxic effects of vitamins described until the end of the last century were previously discussed in Section 2.3 ( Table 3 ). Recently, new correlations between vitamins and human health have been proposed. Details about the best described correlations between the use of vitamins on human health are following summarised:

Vitamin A: Diet supplementation has a positive effect on the blindness and the morbid-mortality in preschool-age children living in developing countries ( http://data.unicef.org/nutrition/vitamin-a.html ). Since 1960, clinical trials have shown that the disorders caused by vitamin A deficiency in developing countries can be prevented with regular dose and this supplementation significantly reduces infant mortality [ 29 – 31 ]. In relation to the other observed associations between vitamin A and certain diseases ( Table 5 ), the evidence obtained do not allow definitive conclusions on the potential benefits of supplementation.

Table 5.

New associations found between vitamins (deficiency or toxicity) and diseases or health states.

AMD: Age-related macular degeneration; CTS: Carpal tunnel syndrome; CVA: stroke (cerebrovascular accident); CVD: cardiovascular disease; DM: diabetes mellitus; OCPs: oral contraceptives; PMS: premenstrual syndrome; TD: tardive dyskinesia.

Vitamin D: The role of vitamin D in bone health is probably one of the better-supported relationships ( Tables 3 and 5 ). The ‘new’ properties related to vitamin D are closely linked to the biological function already described. Thus, several meta-analyses of randomised controlled clinical studies conclude that vitamin D supplementation reduces the risk of falls (derived from the bone fragility) in a 19%, the risk of hip fracture in an 18% and the risk of non-vertebral fractures in a 20% in older adults. The effect on the prevention of falls or fractures is reached using high doses of at least 700–1000 IU/day or at least 400 IU/day, respectively [ 32 – 35 ]. In addition, supplementation has been shown to have a beneficial effect on the balance and muscle strength [ 36 ]. The evidence-based clinical trials suggest that supplementation with vitamin D (1000 IU/day) helps to prevent falls and fractures in the elderly population. However, the studies are not exempt from limitations; in general, these studies were done using supplements of vitamin D combined with calcium, so the effect attributable specifically to the vitamin D is difficult to determine. In addition, in many cases the basal levels of vitamin D and/or calcium uptake is unknown (diet, exposure to the sun, supplements, etc.).

Vitamin B9: intervention trials with folic acid in pregnant women stated that the supplementation reduces the occurrence of neural tube defects (NTD) [ 37 – 39 ]. In USA for instance, the use of folic acid supplements was legally established by the end of 1990, which reduced significantly (20–27%) the prevalence of neural tube defects at birth [ 19 ]. Since then, the consumption of 400 µg/day of folic is recommended to women who want to conceive to prevent birth defects in the foetus [ 40 , 41 ]. In relation to the other observed associations between folic acid and certain diseases ( Table 5 ), the evidences obtained do not make possible to attribute potential benefits to supplementation. Besides, for all the statements about the supplementation with vitamins, there are studies that found negative evidence, including the two cases mentioned above (vitamin D and folic acid).

In relation to the other observed associations between individual vitamins and certain diseases ( Table 5 ), the evidences do not clearly show direct effects of supplementation, either in a positive way (prevention of chronic diseases and/or improvement of human health) or negative (adverse effects linked to the excessive intake), due to the inadequate methodology of the existing studies [ 42 ]. There is a need for new designs of scientific studies to reach valid conclusions. These new designs should consider several aspects such as (i) the initial nutritional status of patients, (ii) the use of homogeneous groups, (iii) the use of control groups and (iv) control of the composition of the ingested food (as it often overestimates the amount of vitamin because it does not consider the bioavailability).

On the other hand, population differences based on genetics could have significant implications in terms of vitamins bio assimilation [ 43 ]. The biochemical individuality and the lack of margins for the safety of vitamins sustain the basic premise of the toxicology ‘the dose makes the poison’. To evaluate the therapeutic efficacy of a vitamin is essential to analyse the dose to be administered, the form of the vitamin used (solution, microencapsulated or crystallised), the source of the vitamin (synthetic or purified from natural sources), the bioavailability and the interaction of a specific vitamin with other nutrients.

Summarising, the analysis set out in this work shows that ‘new’ potential benefits have been attributable to several vitamins. However, most of them are not robustly supported by evidences. In addition, the analysis suggests that the information related to individual vitamins for the prevention and/or treatment of diseases is more consistent than that of a multivitamin complex. In this sense, a systematic review carried out in the USA concludes that the evidence is insufficient to support the use of multivitamin supplements to prevent chronic degenerative diseases [ 42 ].

Finally, it is not surprising that numerous studies published in more than a decade have related some supplements (including vitamins E, C, D, A, and B) with adverse effects on human health. A meta-analysis of 67 trials showed that supplements of vitamin E, vitamin A and beta-carotene might be associated with a higher incidence of mortality [ 44 ]. Another study found a higher incidence (18%) of lung cancer and mortality from all causes (8%) in men who received beta-carotene [ 45 ]. In 2008, a large randomised controlled trial was stopped after reporting that supplementation of vitamin E and selenium resulted in an increase in the incidence of prostate cancer [ 46 ].

6. Use of multivitamin complexes and potential risk of hypervitaminosis

The rate of use of vitamins, minerals and other bioactive compounds available in food or dietary supplements is increasing significantly in advanced societies, especially in USA population, where the multivitamin complexes are the most commonly used supplements [ 47 – 49 ]. Several works state that currently, more than 47% of men and 59% of the women in the USA use supplements for health benefits, and the number of users is growing significantly [ 50 ]. In Europe, the greatest consumption was observed in the countries of the north, especially in Denmark (51.0% among men, 65.8% among women) [ 51 ].

Due to this high market demand, the number of companies producing this kind of dietary supplements is increasing around the work ( http://biomarket.cat/es/69-vitaminas ; http://salud.bayer.es/vitaminas-y-complementos-alimenticios/otras-vitaminas/ ; http://lifestylemarkets.com/vitamins-and-supplements/multivitamins/ ).

There are reports indicating that there could be adverse effects on human health attributable to high consumption of multivitamin complexes. Almost 60,000 cases of toxicity by use of vitamins are reported annually USA poison control centres [ http://www. aapcc.org/annual-reports/ ; [ 52 ]]. The most common adverse effects associated with excessive intake of vitamins (hypervitaminosis) are shown in Table 3 , Section 2.3. Fat-soluble vitamins, for instance, due to its ability to accumulate in the body, have a greater potential for toxicity than water-soluble vitamins. However, the overdose of water-soluble vitamins can also cause toxicity affecting several body systems including the nervous system [ 20 , 53 ]. Between the fat-soluble vitamins, the more toxic are vitamin A and vitamin D. The toxicity of vitamin A can be acute or chronic (IOM, 2006) and high doses cause many toxic manifestations ( Table 3 , Section 2.3). However, there has been no toxic effects of carotenoids (provitamin A), even when eaten in large amounts for weeks or years [ 41 , 54 ], except for an orange/yellow colouring of the skin [ 55 ]. Vitamin D is potentially toxic, especially to small children [ 56 ]. In comparison to vitamins A and D, vitamin E is the least toxic when ingested orally [ 57 ]. In the case of vitamin K, toxic effects have not been observed even intaking large amounts over a long period [ 41 ]; however, a synthetic form of Vitamin K (menadione) has been associated with liver damage, and therefore no longer used therapeutically [ 18 , 41 ].

The evidence on the safety profile of multivitamin complexes in humans has been established through case reports. However, the data reported from these case reports do not allow the accurate identification of maximum tolerable intake level (U). Besides, the toxicological data show that the margins of safety for multivitamin complexes intake are not yet defined, noting toxic doses significantly different in the scientific literature. This suggests that high doses of vitamins, especially of fat-soluble vitamins, should not be given to any group of the population until the safety of such doses is well established and based on scientific evidence.

7. Conclusion

Despite a large number of research works carried out to study the effects of vitamins in human health during the last decades, evidences to attribute potential benefits of vitamins supplementation on either human health or prevention and/or treatment of chronic degenerative diseases are still scarce. The analysis of the research works published during the last 27 years shows that it is impossible to establish robust and universal conclusions about the benefit of vitamin supplementation on human health beyond the prevention and/or treatment of deficiency states (stated during the second half of the twentieth century).

On the other hand, it is important to highlight the high heterogeneity in the clinical and methodological experiments as well as in the tools used to perform these studies, which contributes to making difficult a comparative analysis at large scale. Clinical trials of high methodological quality and a significant number of patients are yet to come. Due to these reasons, the widespread use of multivitamin complexes as diet supplements is still not fully justified.

The most prudent recommendation and scientifically supported for disease prevention is to eat a balanced diet with an emphasis on fruits and vegetables rich in antioxidants [ 58 ], since it is through the diet it is impossible to eat excessive quantities of vitamins. This approach minimises the risk of micronutrient deficiency or excess. However, not all individuals maintain a balanced diet for long periods of time. For this reason, certain circumstances (pregnant women, infants without breastfeeding, vegetarian individuals, elderly, etc.) may require the use of vitamin supplements under control to prevent deficiencies.

Although the potential of the vitamins in the promotion of human health is enormous, it is necessary to assess the risk/benefit ratio in each case. There is much more research to be done to understand the benefits of supplementation in the prevention of diseases and the improvement of human health. Accurate studies about consumption of vitamins by country (including aspects as sex, age, etc.) as well as about food fortification and vitamins protection and stabilisation are yet to come [ 28 ]. A greater knowledge in this area of the science of nutrition will have an impact on clinical practice dietetics and nutrition guidelines for public health.

Acknowledgments

This work has not been funding.

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• 34. Michael YL, Whitlock EP, Lin JS, Fu R, O´Connor EA, Gold R. Primary care—Relevant interventions to prevent falling in older adults: A systematic evidence review for the U. S. Preventive services task force. Annals of Internal Medicine. 2010; 153 :815-825. DOI: 10.7326/0003-4819-153-12-201012210-00008
• 35. Murad MH, Elamin KB, Abu Elnour NO, Elamin MB, Alkatib AA, Fatourechi MM, et al. Clinical review: The effect of vitamin D on falls: A systematic review and meta-analysis. The Journal of Clinical Endocrinology & Metabolism. 2011; 96 (10): 2997-3006. DOI: 10.1210/jc.2011-1193. Epub 27 Jul 2011
• 36. Muir SW, Montero-Odasso M. Effect of vitamin D supplementation on muscle strength, gait and balance in older adults: A systematic review and meta-analysis. Journal of the American Geriatrics Society. 2011; 59 :2291-2300. DOI: 10.1111/j.1532-5415.2011.03733.x
• 37. Stamm RA, Houghton LA. Nutrient intake values for folate during pregnancy and lactation vary widely around the World. Nutrients. 2013; 5 (10):3920-3947. DOI: 10.3390/nu5103920
• 38. Imbard A, Benoist JF, Blom HJ. Neural tube defects, folic acid and methylation. International Journal of Environmental Research and Public Health. 2013; 10 (9):4352-4389. DOI: 10.3390/ijerph10094352
• 39. Liew SC. Folic acid and diseases—Supplement it or not? Revista da Associação Médica Brasileira. 2016; 62 (1):90-100. DOI: 10.1590/1806-9282.62.01.90
• 40. Czeizel AE, Dudás I. Prevention of the first occurrence of neural-tube defects by periconceptional vitamin supplementation. The New England Journal of Medicine. 1992; 327 (26):1832-1835. DOI: 10.1056/NEJM199212243272602
• 41. Institute of Medicine (IOM) Standing Committee on the Scientific Evaluation of Dietary Reference Intakes and its Panel on Folate, Other B Vitamins, and Choline. Folate. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington: National Academies Press; 1998. 196-305. Available in: https://www.ncbi.nlm.nih.gov/pubmed/23193625
• 42. Huang HY, Caballero B, Chang S, Alberg AJ, Semba RD, Schneyer CR et al. The efficacy and safety of multivitamin and mineral supplement use to prevent cancer and chronic disease in adults: A systematic review for a National Institutes of Health state-of-the-science conference. Annals of Internal Medicine. 2006; 145 (5):372-385. Available in: http://annals.org/aim/article/728199/efficacy-safety-multivitamin-mineral-supplement-use-prevent-cancer-chronic-disease
• 43. Kresevic DM, Denton JE, Burant CJ, Pallaki M. Racial difference in response to Vitamin D supplementation. Journal of the National Medical Association. 2015; 107 (2):18-24. DOI: 10.1016/S0027-9684(15)30020-1
• 44. Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C. Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases. The Cochrane Database Syst Rev. 2008 Apr 16;(2):CD007176. doi: 10.1002/14651858.CD007176. Review. Update in: Cochrane Database Syst Rev. 2012;3:CD007176
• 45. Cardenas E, Ghosh R. Vitamin E: A dark horse at the crossroad of cancer management. Biochemical Pharmacology. 2013; 86 (7):845-852. DOI: 10.1016/j.bcp.2013.07.018
• 46. Lippman SM, Klein EA, Goodman PJ, Lucia MS, Thompson IM, Ford LG, et al. Effect of selenium and vitamin E on risk of prostate cancer and other cancers: The selenium and vitamin E cancer prevention trial (SELECT). JAMA. 2009; 301 (1):39-51. DOI: 10.1001/jama.2008.864
• 47. NIH State-of-the-Science Panel. National Institutes of Health state-of-the-science conference statement: Multivitamin/mineral supplements and chronic disease prevention. The American Journal of Clinical Nutrition. 2007; 85 :257-264
• 48. Gahche J, Bailey R, Burt V, Hughes J, Yetley E, Dwyer J, et al. Dietary supplement use among U.S. Adults has increased since NHANES III (1988-1994). NCHS Data Brief. 2011;( 61 ):1-8. Available in: http://www.cdc.gov/nchs/data/databriefs/db61.htm
• 49. Bailey RL, Gahche JJ, Lentino CV, Dwyer JT, Engel JS, Thomas PR, et al. Dietary supplement use in the United States, 2003-2006. Journal of Nutrition. 2011; 141 :261-266. DOI: 10.3945/jn.110.133025
• 50. Soni MG, Thurmond TS, Miller ER, Spriggs T, Bendich A, Omaye ST. Safety of vitamins and minerals: Controversies and perspective. Toxicological Sciences. 2010; 118 (2):348-355. DOI: 10.1093/toxsci/kfq293
• 51. Skeie G, Braaten T, Hjartåker A, Lentjes M, Amiano P, Jakszyn P, et al. Use of dietary supplements in the European prospective investigation into cancer and nutrition calibration study. European Journal of Clinical Nutrition. 2009; 63 (4):226-238. DOI: 10.1038/ejcn.2009.83
• 52. Mowry JB, Spyker DA, Brooks DE, McMillan N, Schauben JL. 2014 Annual report of the American association of poison control centers’ National Poison Data System (NPDS): 32nd Annual Report. Clinical Toxicology. 2015; 53 (10):962-1147. DOI: 10.3109/15563650.2015.1102927
• 53. Chawla J, Kvarnberg D. Hydrosoluble vitamins. Handbook of Clinical Neurology. 2014; 120 :891-914. DOI: 10.1016/B978-0-7020-4087-0.00059-0
• 54. Hathcock JN, Hattan DG, Jenkins MY, McDonald JT, Sundaresan PR, Wilkening VL. Evaluation of vitamin A toxicity. The American Journal of Clinical Nutrition. 1990; 52 (2):183-202
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• 58. Lock K, Pomerleau J, Causer L, Altmann DR, McKee M. The global burden of disease attributable to low consumption of fruit and vegetables: Implications for the global strategy on diet. Bulletin of the World Health Organization. 2005; 83 (2):100-108. Available in: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2623811/

© 2017 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution 3.0 License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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• Table Of Contents

What are vitamins?

Vitamins are any of several organic substances that are necessary in small quantities for normal health and growth in higher forms of animal life. They are usually designated by selected letters of the alphabet, as in vitamin C, though they are also designated by chemical names.

What are the two main groups of vitamins?

Traditionally vitamins are separated into two groups, the water-soluble and the fat-soluble vitamins. The water-soluble vitamins are thiamin, riboflavin, niacin, vitamin B 6 , folic acid, vitamin B 12 , pantothenic acid, biotin, and vitamin C. The fat-soluble vitamins are vitamin A, vitamin E, vitamin D, and vitamin K.

What are sources for vitamins?

Both plants and animals are important natural sources for vitamins. All vitamins can be either synthesized or produced commercially from food sources and are available for human consumption in pharmaceutical preparations.

Inadequate intake of specific vitamins can result in a characteristic deficiency disease (hypovitaminosis), and the severity depends upon the degree of vitamin deprivation. Symptoms may be specific (e.g., functional night blindness with vitamin A deficiency), nonspecific (e.g., loss of appetite, failure to grow), or irreversible (e.g., damage to the cornea of the eye, nerve tissue, calcified bone).

What are the vitamin requirements in human beings?

There is no uniform agreement concerning vitamin requirements for humans, but recommended daily vitamin intakes are sufficiently high to account for individual variation and normal environmental stresses.

vitamin , any of several organic substances that are necessary in small quantities for normal health and growth in higher forms of animal life. Vitamins are distinct in several ways from other biologically important compounds such as protein s, carbohydrate s, and lipid s. Although these latter substances also are indispensable for proper bodily functions, almost all of them can be synthesized by animals in adequate quantities. Vitamins, on the other hand, generally cannot be synthesized in amounts sufficient to meet bodily needs and therefore must be obtained from the diet or from some synthetic source. For this reason, vitamins are called essential nutrients. Vitamins also differ from the other biological compounds in that relatively small quantities are needed to complete their functions. In general these functions are of a catalytic or regulatory nature, facilitating or controlling vital chemical reactions in the body’s cells. If a vitamin is absent from the diet or is not properly absorbed by the body, a specific deficiency disease may develop.

Vitamins are usually designated by selected letters of the alphabet, as in vitamin D or vitamin C , though they are also designated by chemical names, such as niacin and folic acid . Biochemists traditionally separate them into two groups, the water-soluble vitamins and the fat-soluble vitamins. The common and chemical names of vitamins of both groups, along with their main biological functions and deficiency symptoms, are listed in the table.

Biological significance of vitamins

Some of the first evidence for the existence of vitamins emerged in the late 19th century with the work of Dutch physician and pathologist Christiaan Eijkman . In 1890 a nerve disease (polyneuritis) broke out among his laboratory chickens. He noticed that the disease was similar to the polyneuritis associated with the nutritional disorder beriberi . In 1897 he demonstrated that polyneuritis was caused by feeding the chickens a diet of polished white rice but that it disappeared when the animals were fed unpolished rice. In 1906–07 British biochemist Sir Frederick Gowland Hopkins observed that animals cannot synthesize certain amino acids and concluded that macronutrients and salts could not by themselves support growth.

In 1912—the same year that Hopkins published his findings about the missing nutrients, which he described as “accessory” factors or substances—a Polish scientist, Casimir Funk , demonstrated that polyneuritis produced in pigeons fed on polished rice could be cured by supplementing the birds’ diet with a concentrate made from rice bran, a component of the outer husk that was removed from rice during polishing. Funk proposed that the polyneuritis arose because of a lack in the birds’ diet of a vital factor (now known to be thiamin ) that could be found in rice bran. Funk believed that some human diseases, particularly beriberi, scurvy , and pellagra , also were caused by deficiencies of factors of the same chemical type. Because each of these factors had a nitrogen-containing component known as an amine , he called the compounds “vital amines,” a term that he later shortened to “vitamines.” The final e was dropped later when it was discovered that not all of the vitamins contain nitrogen and, therefore, not all are amines.

In 1913 American researcher Elmer McCollum divided vitamins into two groups: “fat-soluble A” and “water-soluble B.” As claims for the discovery of other vitamins multiplied, researchers called the new substances C, D, and so on. Later it was realized that the water-soluble growth factor , vitamin B, was not a single entity but at least two—only one of which prevented polyneuritis in pigeons. The factor required by pigeons was called vitamin B 1 , and the other factor, essential for rats, was designated vitamin B 2 . As chemical structures of the vitamins became known, they were also given chemical names, e.g., thiamin for vitamin B 1 and riboflavin for vitamin B 2 .

For healthy adults, taking multivitamins daily is not associated with a lower risk of death

• Posted: June 26, 2024

240-760-6600

A new study questions the benefits of regular multivitamin use.

A large analysis of data from nearly 400,000 healthy U.S. adults followed for more than 20 years has found no association between regular multivitamin use and lower risk of death. The study, led by researchers at the National Institutes of Health’s National Cancer Institute, was published June 26, 2024, in JAMA Network Open .

Many adults in the United States take multivitamins with the hope of improving their health. However, the benefits and harms of regular multivitamin use remain unclear. Previous studies of multivitamin use and mortality have yielded mixed results and been limited by short follow-up times.

To more deeply explore the relationship between long-term regular multivitamin use and overall mortality and death from cardiovascular disease and cancer, the researchers analyzed data from three large, geographically diverse prospective studies involving a total of 390,124 U.S. adults who were followed for more than 20 years. The participants included in this analysis were generally healthy, with no history of cancer or other chronic diseases.

Because the study population was so large and included lengthy follow-up and extensive information on demographics and lifestyle factors, the researchers were able to mitigate the effects of possible biases that may have influenced the findings of other studies. For example, people who use multivitamins may have healthier lifestyles in general, and sicker patients may be more likely to increase their use of multivitamins.

The analysis showed that people who took daily multivitamins did not have a lower risk of death from any cause than people who took no multivitamins. There were also no differences in mortality from cancer, heart disease, or cerebrovascular diseases. The results were adjusted for factors such as race and ethnicity, education, and diet quality. 

The researchers noted that it is important to evaluate multivitamin use and risk of death among different kinds of populations, such as those with documented nutritional deficiencies, as well as the potential impact of regular multivitamin use on other health conditions associated with aging.

Erikka Loftfield, Ph.D., M.P.H., Division of Cancer Epidemiology and Genetics, National Cancer Institute

“Multivitamin Use and Mortality Risk in 3 Prospective US Cohorts” appears June 26, 2024, in JAMA Network Open .

About the National Cancer Institute (NCI):  NCI leads the National Cancer Program and NIH’s efforts to dramatically reduce the prevalence of cancer and improve the lives of people with cancer. NCI supports a wide range of cancer research and training extramurally through grants and contracts. NCI’s intramural research program conducts innovative, transdisciplinary basic, translational, clinical, and epidemiological research on the causes of cancer, avenues for prevention, risk prediction, early detection, and treatment, including research at the NIH Clinical Center—the world’s largest research hospital. Learn more about the intramural research done in NCI’s Division of Cancer Epidemiology and Genetics . For more information about cancer, please visit the NCI website at  cancer.gov  or call NCI’s contact center at 1-800-4-CANCER (1-800-422-6237).

About the National Institutes of Health (NIH):  NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit  nih.gov .

Daily Multivitamin Use In Healthy Adults Doesn’t Decrease Risk Of Death, Study Suggests: What To Know About Pros And Cons Of Multivitamins

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Researchers suggest Americans get their nutrients from food rather than supplements after a new study found daily multivitamin use doesn’t decrease the risk of death, which is the newest research in the long debated topic about the benefits of multivitamins.

a handful of vitamins.

The researchers used the health records of over 390,000 participants with a median age of 61.5 years who were generally healthy, had no history of chronic disease and were followed for over 20 years, according to the study published Wednesday in JAMA Network Open.

People with healthier lifestyles and those who are sick may have an increased chance of taking multivitamins, so the researchers mitigated these effects so they didn’t have an impact on the study’s results.

The group of participants who took daily multivitamins had lower BMIs and better sleep quality than the participants who didn’t use daily multivitamins, and were slightly more likely to be college educated.

However, the study found those who took daily multivitamins had 4% higher mortality risk for all causes, though there were no differences in mortality risks from cancer, heart disease or cerebrovascular diseases like stroke, aneurysms.

Since the study’s population consisted of generally healthy adults, the researchers noted further research must be done to include other groups like people with nutrient deficiencies, and to evaluate the potential impact of regular multivitamin use on other health conditions associated with aging.

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Crucial Quote

“Refocusing nutrition interventions on food, rather than supplements, may provide the mortality benefits that multivitamins cannot deliver,” researchers with the National Cancer Institute wrote as part of a commentary on the JAMA study. “Vegetables, fruits, legumes and cereal grains are staples in areas of remarkable longevity.”

Is There Any Evidence Multivitamins Work?

Though the benefits of multivitamins have been a long debated topic, over 31% of Americans 19 years and older take multivitamins . Men who take daily multivitamins may have an 8% lower cancer risk and a lower risk of developing cataracts, according to a previous JAMA study . Several studies have found multivitamins can improve memory in older adults. Multivitamins may also offer benefits for those with mood disorders. Older male participants who took multivitamins over an eight-week period had significant reductions in depression and anxiety compared to the placebo group, according to research published in Human Psychopharmacology: Clinical & Experimental.

What Vitamins May Actually Work?

Taking standalone vitamins may provide some benefits. Doctors recommend patients with vitamin deficiencies like vitamin D take supplements, especially those with lactose intolerance, milk allergies, fat absorption issues and people with darker skin tones and more melanin, according to Yale Medicine. Vitamins are also useful during pregnancy: Pregnant women can benefit from taking prenatal vitamins containing vitamin D and calcium to help the baby’s teeth and bones grow, according to the Mayo Clinic.

Are Multivitamins Regulated By The Fda?

Multivitamins, herbs, minerals and other dietary supplements are not approved by the Food and Drug Administration, though the FDA regulates them. However, most of the regulation happens after they hit the shelves, and many companies manufacture and sell multivitamins without notifying the FDA.

$177.5 billion. That’s how much the global dietary supplement industry was worth in 2023, according to market research firm Grand View Research. This number is expected to grow by 9% between 2024 and 2030.

Key Background

The U.S. Preventive Services Task Force concluded in 2022 there was “little to no benefit” in taking vitamins and mineral supplements, and recommended against the use of beta carotene or vitamin E supplements for the prevention of cardiovascular disease or cancer. Multivitamin use did not reduce the risk of cancer or heart disease in participants in a 2021 study by the USPSTF. Researchers also found taking iron supplements—which is added to many multivitamins—can lead to iron overload and increase the risk of diabetes, dementia and heart disease.

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Wednesday, June 26, 2024

For healthy adults, taking multivitamins daily is not associated with a lower risk of death

Findings come from an NIH analysis of more than two decades of dietary data from 390,124 U.S. adults.

A large analysis of data from nearly 400,000 healthy U.S. adults followed for more than 20 years has found no association between regular multivitamin use and lower risk of death. The study, led by researchers at the National Institutes of Health’s National Cancer Institute, was published June 26, 2024, in JAMA Network Open .

Many adults in the United States take multivitamins with the hope of improving their health. However, the benefits and harms of regular multivitamin use remain unclear. Previous studies of multivitamin use and mortality have yielded mixed results and been limited by short follow-up times.

To more deeply explore the relationship between long-term regular multivitamin use and overall mortality and death from cardiovascular disease and cancer, the researchers analyzed data from three large, geographically diverse prospective studies involving a total of 390,124 U.S. adults who were followed for more than 20 years. The participants included in this analysis were generally healthy, with no history of cancer or other chronic diseases.

Because the study population was so large and included lengthy follow-up and extensive information on demographics and lifestyle factors, the researchers were able to mitigate the effects of possible biases that may have influenced the findings of other studies. For example, people who use multivitamins may have healthier lifestyles in general, and sicker patients may be more likely to increase their use of multivitamins.

The analysis showed that people who took daily multivitamins did not have a lower risk of death from any cause than people who took no multivitamins. There were also no differences in mortality from cancer, heart disease, or cerebrovascular diseases. The results were adjusted for factors such as race and ethnicity, education, and diet quality. 

The researchers noted that it is important to evaluate multivitamin use and risk of death among different kinds of populations, such as those with documented nutritional deficiencies, as well as the potential impact of regular multivitamin use on other health conditions associated with aging.

Erikka Loftfield, Ph.D., M.P.H., Division of Cancer Epidemiology and Genetics, National Cancer Institute

  “Multivitamin Use and Mortality Risk in 3 Prospective US Cohorts” appears June 26, 2024, in JAMA Network Open .

About the National Cancer Institute (NCI):  NCI leads the National Cancer Program and NIH’s efforts to dramatically reduce the prevalence of cancer and improve the lives of people with cancer. NCI supports a wide range of cancer research and training extramurally through grants and contracts. NCI’s intramural research program conducts innovative, transdisciplinary basic, translational, clinical, and epidemiological research on the causes of cancer, avenues for prevention, risk prediction, early detection, and treatment, including research at the NIH Clinical Center—the world’s largest research hospital. Learn more about the intramural research done in NCI’s Division of Cancer Epidemiology and Genetics . For more information about cancer, please visit the NCI website at  cancer.gov  or call NCI’s contact center at 1-800-4-CANCER (1-800-422-6237).

About the National Institutes of Health (NIH): NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov .

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Is Fish Oil Helpful or Harmful for the Heart?

Despite decades of research, the evidence for omega-3 supplements is murky.

By Alice Callahan

In 1970, two Danish researchers traveled to Greenland to investigate a nutritional paradox: The Inuit people living in the region consumed foods very high in fat, yet reportedly had very low rates of heart attacks.

That observation flew in the face of nutrition dogma at the time, which held that eating fatty foods — like whale and seal meat and oily fish — would clog your arteries and cause heart disease.

The Inuit on Greenland, a Danish territory, had lower levels of blood cholesterol and triglycerides than people back in Denmark, the researchers reported . The reason, they hypothesized, was that the Inuit diet was rich in omega-3 fatty acids — particularly EPA and DHA, which are concentrated in fish and the animals that eat them.

These findings sparked decades of scientific and commercial interest in the role omega-3 fatty acids play in heart health, even after later studies suggested that, in fact, the Inuit had rates of heart disease similar to those found in Europe, the United States and Canada. Today, omega-3 supplements are among the most popular in the United States, surpassed only by multivitamins and vitamin D. Among U.S. adults 60 and older, about 22 percent reported taking omega-3s in a 2017-2018 survey.

Unlike most other supplements , fish oil has been rigorously studied, said Dr. JoAnn Manson, a professor of medicine at Harvard Medical School. But the results of those studies have been mixed, leaving researchers and doctors still debating whether fish oil is beneficial for heart health. They have also revealed that taking fish oil is linked to a slightly greater risk of developing atrial fibrillation , a type of irregular heartbeat.

Here’s where the evidence for both the benefits and risks of fish oil stands today.

A boatload of studies, but unclear benefits

After reading the dispatches from Greenland, researchers began looking at people elsewhere in the world and finding, in study after study , that those who consumed fish at least once per week were less likely to die from coronary heart disease than those who rarely ate fish. In animal experiments , they found that fish oil helped keep electrical signaling in heart cells functioning properly, said Dr. Dariush Mozaffarian, a cardiologist and director of the Food is Medicine Institute at Tufts University.

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Schoolchildren know more about vitamins than their parents, research finds

A new survey of 2,000 adults and 1,000 children aged 6-16 has found British kids scored more than adults on the majority of vitamin and nutrition questions

• 16:05, 1 JUL 2024

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After scrutinising separate surveys of 2,000 adults and 1,000 children aged 6-16, it emerged that youngsters outperformed their elders on most questions. The study revealed that 20 per cent of the younger generation knew there are 13 different vitamins, compared to a mere five per cent of adults.

Furthermore, 38 per cent of schoolchildren were aware that the body can naturally produce vitamin D, in contrast to 31 per cent of adults. Kids also demonstrated superior knowledge about vitamin D's role in bone growth and vitamin A's vision-enhancing properties.

They were also more clued up about how vitamins C and D boost the immune system, according to research by health food firm Plenish.

Emily English, an expert nutritionist who has joined forces with Plenish as its 'Chief Nutrition Officer', commented: "The research highlights a significant knowledge gap among British adults about the importance of vitamins and how to consume them. As a nutritionist, I witness the daily consequences of vitamin deficiency and I urge adults to enhance their knowledge of essential vitamins. Incorporating these vitamins into your daily routine is simple: consume a balanced diet, make sure you hit your five-a-day, or add a vitamin-enriched shot."

In response to this knowledge deficit, Plenish has launched the 'Little Shot Shop' on London's Portobello Road, staffed by children. These young employees shared crucial vitamin and nutrition information with passers-by and tested adults on their vitamin knowledge.

The research further revealed that children are more clued up about vitamins than adults, with 37 per cent confident in their knowledge compared to just 24 per cent of grown-ups. The study also found some surprising misconceptions among adults, with over a quarter (27 per cent) wrongly identifying broccoli as a protein source and one in 10 (nine per cent) believing ketchup counts towards their five-a-day.

Shockingly, almost a quarter (24 per cent) of adults hadn't even heard of the World Health Organisation's 'five-a-day' campaign. Additionally, two in 10 (21 per cent) were under the mistaken belief that tomatoes are vegetables, while over a third (36 per cent) didn't know that ginger is a root.

For those keen to brush up on their vitamin knowledge, Plenish has launched a Vitamin Quiz where Brits can test if they're smarter than kids.

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