For the first half of the 20th century, much of nutrition research focused on discovering essential vitamins and minerals. By the second half of the 20th century, more and more Americans were taking vitamins and mineral supplements with the hope that they would improve their health. At the same time, the growing food supplement industry started hawking multi-vitamin and mineral supplements as an inexpensive way to ensure better health. Consumers were told that with this "insurance," they could remain healthy even if they didn't always eat right. No doubt many Americans have bought into this food supplement industry mantra, believing that simply taking some form of multi-vitamin supplement will help keep them healthy without needing to eat healthful meals. If only the key to sound nutrition and better health were so simple.The U.S. Preventive Services Task Force recently reviewed three controlled clinical trials of the impact of taking a multivitamin supplement, along with another 24 trials of single or paired vitamins versus a placebo. The result of these studies was that the people randomly assigned to take the supplements experienced no improvement in health or longevity compared with those taking a placebo. These studies included more than 400,000 people and yet were unable to find any clear evidence of any beneficial health effect on all-cause mortality, cardiovascular disease events, or cancer incidence/mortality.[i]Another research team evaluated the use of a daily multivitamin supplement to see if it could help prevent cognitive decline among nearly 6,000 male physicians aged 65 years or older in the Physicians' Health Study II. After 12 years of follow-up, the results of this controlled clinical trial showed no significant differences in overall cognitive performance or verbal memory among the multivitamin takers and the placebo group. [ii]Yet another research team evaluated the potential benefits of taking a high-dose, 28-component multivitamin/mineral supplement in 1,708 men and women who had all suffered a previous heart attack. After a median follow-up of 4.6 years, the data again showed no significant difference in recurrent cardiovascular events in those taking the dietary supplement compared with those taking a placebo.[iii]These studies serve only to further undermine the dubious idea that taking vitamin and/or mineral supplements can provide some sort health "insurance" against common diseases that increasingly plague modern societies. Other research clearly shows that what you eat does indeed impact the risk of cardiovascular ills, cancer, diabetes, osteoporosis, and dementia. If Americans were dying from pellagra, scurvy, beriberi, and other nutritional deficiency diseases, then it is clear that talking a multivitamin supplement would pretty much eliminate such deficiency diseases. However, Americans die far more from nutritional excesses than they do from nutrient deficiencies. Nutrition research shows that modern diets promote disease largely because they are too high in salt, saturated fat, and cholesterol and also contain too many calories coming from foods composed largely of refined fats, oils, grains, and sugars. Many of these "junk" foods and other foods are now fortified with an assortment of vitamins and/or minerals, thus making the chance of developing vitamin and mineral deficiencies less likely, even in those with diets full of such foods.In an accompanying editorial in the December 2013 issue of the Annals of Internal Medicine, which considered these new studies and all previously published controlled clinical trials on the supposed benefits of multi-nutrient supplements, Dr. Gauller and colleagues stated:

"Beta-carotene, vitamin E, and possibly high doses of vitamin A supplements are harmful. Other antioxidants, folic acid and B vitamins, and multivitamin and mineral supplements are ineffective for preventing mortality or morbidity due to major chronic diseases. Although available evidence does not rule out small benefits or harms or large benefits or harms in a small subgroup of the population, we believe that the case is closed— supplementing the diet of well-nourished adults with (most) mineral or vitamin supplements has no clear benefit and might even be harmful. These vitamins should not be used for chronic disease prevention. Enough is enough." [iv]

Dr. Gauller did not dismiss all vitamin and mineral supplements. They can be beneficial in people who are actually deficient in one or more nutrients. Younger women and children do sometimes become iron deficient, and many older people become deficient in vitamin B-12 in large part because their ability to absorb it becomes impaired. Dr. Gauller notes that there is ongoing research into the potential benefits of vitamin D supplements, since many Americans may need more than they can get from their diets. Many Americans may get less than optimal amounts of vitamin K, potassium and magnesium but these nutrients are often not found in adequate amounts in most multi-vitamin/mineral supplements.Bottom Line: It is time for health professionals to tell people unequivocally that the key to good health and longevity is not taking a multi-nutrient supplement, but rather adopting a healthful diet and exercise program. That means a diet with more whole grains, fruits, and vegetables, along with modest amounts of nonfat dairy or fortified soymilk, coupled perhaps with small amounts of omega-3 rich seafood.By James J. Kenney, PhD, FACN.References: [i] Fortmann SF, et al. Ann Intern Med. 2013;159:824-834[ii] Grodstein F, et. al. Ann Intern Med. 2013;159:806-814[iii] Lamas GA, et. al. Ann Intern Med. 2013;159:717-804[iv] Gualler E, et.al. Ann InternMed.159:850-851, 2013