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Multiple vitamins and supplements are available in every shop. They are considered an important addition to healthy diet. However, new research evidences suggest that many supplements provide little, if any, positive effect on health.

Vitamins are nutritional substances that, when ingested in adequate, limited amounts, help the body perform its natural functions. For example, vitamin D helps maintaining healthy bones and vitamins of the B complex help producing certain vital proteins called enzymes.

The designation of vitamin is attributed to any substance that the body cannot synthesize in sufficient quantities to supply its needs. As a consequence, humans get most of their vitamins from the food they eat. Everyone is familiar with vitamin C being widely present in oranges or kiwis, for instances. Nevertheless, multivitamin supplements are perhaps the most famous dietary supplements worldwide and the most commonly used in developed countries. In a study conducted between 1999 and 2000 in the U.S.A., 35% of adults reported recent use of multivitamin supplements. In 2010, the supplement industry reached a staggering $28 billion in sales in the U.S. alone, with similar trends having been observed in the UK and in other European countries.

Vitamins are important. But are the vitamin supplements important too?

People resort to vitamin supplements with the goal of ensuring adequate intake or preventing/complementing the treatment of a disease. But do vitamin supplements really favor the average consumer? Do they actually have a role in promoting health and preventing disease? Several scientifically sound studies have been conducted to analyze if the additional vitamin intake is beneficial under several circumstances.

Most of these studies have actually showed that vitamin supplements not only offer little benefit but can even cause harm.

A meta-analysis conducted in 2010 by researchers from several institutions, including the Johns Hopkins School of Medicine, looked at the results of 14 clinical trials that evaluated the relationship of folic acid (also known as vitamin B9) supplementation with cardiovascular events. Analyzing the data collected from nearly 39 thousands individuals, this research group demonstrated that, although previous studies had suggested otherwise, ingesting additional amounts of folic acid has no effect whatsoever in cardiovascular disease, coronary heart disease or mortality prevention in general. In fact, when administered to patients with high baseline levels of a substance called homocysteine, folic acid supplements can even increase the risk for the listed conditions.

Another analysis looked at the famous vitamin D and how it correlated with the prevention of medical conditions like diabetes, colorectal cancer and cardiovascular disease. Appropriate intake of vitamin is essential to overall health, more specifically bone health, but a significant number of observational studies had suggested that higher levels of vitamin D could be helpful in prevention of multiple non-bone-related conditions. But when Professor Philippe Autier from International Prevention Research Institute in France looked at the overall results of 172 reported clinical trials, he found that people who were given supplemental doses of vitamin D had no significant reduction in the risk of developing any disease.

Continue reading after recommendations

  • MILLER, E. R., JURASCHEK, S., ROBERTO PASTOR-BARRIUSO, BAZZANO, L. A., APPEL, L. J. & GUALLAR, E. 2012. Meta-Analysis of Folic Acid Supplementation Trials on Risk of Cardiovascular Disease and Risk Interaction With Baseline Homocysteine Levels. American Journal of Cardiology, 106, 517-527
  • MOYER, V. A. 2013. Vitamin D and Calcium Supplementation to Prevent Fractures in Adults: U.S. Preventive Services Task Force Recommendation Statement. Annals of Internal Medicine, 158, 691-696
  • HUANG, H.-Y., CABALLERO, B., CHANG, S., ALBERG, A. J., SEMBA, R. D., SCHNEYER, C. R., WILSON, R. F., CHENG, T.-Y., VASSY, J., PROKOPOWICZ, G., II, G. J. B. & BASS, E. B. 2006. 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, 145, 372-385
  • GUALLAR, E., STRANGES, S., MULROW, C., APPEL, L. J. & III, E. R. M. 2013. Enough Is Enough: Stop Wasting Money on Vitamin and Mineral Supplements Annals of Internal Medicine, 159, 850-851.
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