Americans spend billions of dollars on multivitamin-mineral supplements; are they getting a return on their investment? Not always. Numerous studies involving hundreds of thousands of men and women of all ages and genetic backgrounds have found little or no long-lasting benefits from taking a multivitamin-mineral daily supplement. One large study followed the lives of 182,000 men and women; those who took daily multivitamins did not live longer or have less heart disease or cancer, the two primary killers of Americans (Am J Epidemiol 173: 906, 2011). When 161,000 postmenopausal women were followed; those who took daily multivitamins were not less likely to develop breast, ovarian, or any other cancer as compared to those women who did not take multivitamins (Arch Intern Med 169: 294, 2009). When 83,000 middle-aged to elderly men were followed; those who took daily multivitamins were no less likely to die from coronary heart disease or stroke as compared to men who did not take multivitamins (Arch Intern Med 162: 1472, 2002).
So maybe you're still hoping that taking multivitamins, at the very least, might offer some modest benefits for your substantial investment of time and money. Sadly, after many decades of research, the evidence for even modest health benefits is still very iffy. Even when researchers examined the benefits of multivitamins for symptoms associated with the common cold, they could find no significant health benefits (J Am Geriatr Soc 55:35, 2007; Br Med J 331: 324, 1005; JAMA 288: 715; 2002).
What about the brain? Surely, multivitamins help the brain; just look at the hundreds of claims on the internet! Nope. When healthy older men and women, aged 60-91 years, were given daily multivitamin supplements for six months they demonstrated no significant improvements on memory or other cognitive function tests, as compared to being given a sugar-pill (Prev Med 41:253, 2005; Nutr J. 6:10, 2007). Vitamin E supplements are no longer recommended for brain health, indeed, the high doses originally thought to help slow the onset of dementia with aging is now recognized to increase the risk of cerebral hemorrhage (Ann Pharmacother, 39: 2073, 2005).
In spite of a total lack of evidence that multivitamins offer any real long-term health benefits we are all addicted to them. This is why Americans are said to produce the most expensive urine in the world; we merely excrete whatever our bodies do not need immediately. However, this is actually an advantage because it protects us from the toxic side-effects of consuming too much of the certain vitamins. For example, Vitamins A, D, E & K are particularly risky because they are fat soluble and can collect in body fat pads or the brain; however, toxicity is usually only observed after ingesting exceptionally high doses. We need them for good health but too much can be quite harmful.
Concerns about vitamins and the balance of their risks vs. benefits were expressed during the early 1950s when parents learned that powerful chemicals, i.e. vitamins and minerals, were being added to their child's favorite breakfast cereals. The solution for some manufacturers was to offer the pills as effigies of popular cartoon characters. As recently as 2004, Denmark outlawed some vitamin fortified cereals because of concerns that extremely high levels of vitamin B-6, calcium, folic acid and iron might achieve toxic levels if eaten daily; the risk is particularly high for young children - the principle consumer of many enriched cereals. The Danes might be overreacting; however it's probably not a good idea to take a daily multivitamin if you're eating a cereal containing 100% of the daily recommended levels.
Overall, most of us are wasting our money because we've been completely sold on the belief that we need these chemicals to be healthy. The epidemiological evidence basically does not support this belief. Indeed, some things that were once thought to be critical for our good health, such as selenium or vitamin A, are simply not as big of a concern; indeed, recent recommendations are to avoid high doses of these two supplements (Ann Inter Med 147:114, 2007).
However, and this cannot be overstated, some people do need supplements of certain vitamins and minerals either because of poor diets, disease states, advanced age, gender or the availability of sunshine, to name just of few of the major reasons. We are all aware of the recommendations that some of us should produce more vitamin D, take folic acid during pregnancy, take certain B-vitamins for better mental and physical health, and consume additional iron particularly if you're a woman under 50 years. Due to the critical role of iron in brain chemistry, anemia is associated with apathy and depression. Iron deficiency has also been found in children with attention-deficit/hyperactivity disorder (J Nutr Health Aging, 10:377, 2006). Finally, you should try to get calcium into your diet no matter who you are.
Moderation is still the best approach for most of us: that would include moderation in the number of calories consumed each day, moderation in your daily exercise routine, and a good attempt to obtain your vitamins and minerals from their natural sources.
© Gary L. Wenk, Ph.D. Author of Your Brain on Food (Oxford University Press, 2010)