It is not too surprising that the correlation of increased mortality was greatest with iron supplementation as post-menopausal women are advised to avoid multivitamins with iron after they cease menstruating. Because of iron’s oxidative properties, a build up of iron in the body can have multiple negative health consequences, including an increased risk of Alzheimer’s, Parkinson’s, arthritis, heart disease, osteoporosis and cataracts. For this reason, most “senior” multivitamin formulas don’t contain iron.
Another recent study found that Vitamin E supplementation may increase (rather than decrease) the risk of prostate cancer in men. The study actually began in 2001 to examine whether or not Vitamin E supplements decreased the risk of prostate cancer. Their initial findings after the study ended in 2008 suggested that it did not. A follow-up to the study, however, found that men in the study who took daily supplements of 400 international units (IU) of vitamin E (about 18 times the recommended daily dietary allowance of 22.4 IU) were 17 percent more likely to develop prostate cancer over a seven-year period than men who took a placebo pill.
In addition to relying on supplements for nutrition, many people also consume fortified foods, furthering their risk for over-supplementation. Though we cannot conclude from these studies that regular use of nutrition supplements (without severe deficiencies) increases mortality, these studies do suggest that it is not without potential risk. Obtaining nutrients from a diet of whole foods , by comparison, is the best, safest way to ensure that you are meeting all of your nutritional needs. Save your money on supplements (with the possible exception of a good probiotic and an omega 3 supplement if you avoid fish) and spend it instead on high-quality, unprocessed whole foods.