Medicine Today: Vitamins can cause harm

Do you take vitamins or supplements? A new series of studies in the Annals of Internal Medicine suggest they have no significant benefit to your health and for some adults, might actually cause harm.


One in three Americans use multivitamins, and almost $30 billion worth of supplements are sold each year. However, because supplements are largely ignored in medical school, many doctors are not trained on how to advise patients in their use. Three recently published studies address this issue.

In the first vitamin study, Dr. Stephen Fortmann and colleagues at the Kaiser Permanente Center for Health Research pooled data from multiple earlier studies to determine the benefit of taking vitamins in otherwise healthy adults with no other medical problems. They specifically examined multivitamins, vitamin A, vitamin C, vitamin D, folic acid, selenium, and beta-carotene. They found that taking these vitamins did not have any effect on the risk of developing heart disease or cancer, or of dying. They also found that in adults who were at high risk for developing lung cancer (such as smokers or asbestos workers), supplements of beta-carotene increased the risk of lung cancer.

In a second study, Dr. Gervasio A. Lamas, the chairman of medicine at Mount Sinai Medical Center, and colleagues divided elderly patients who had heart attacks into two groups.

One group received multivitamins and a second did not. They followed the two groups for about 5 years and found no difference in mortality or other heart-related events between the

In a third study, Dr. Fracine Grodstein and colleagues from Harvard Medical School studied elderly physicians for about 8 years. They found that those who took multivitamins did not have better cognitive function compared to those who did not.

Taking vitamins can be a difficult decision. Vitamins have anecdotally been assigned various positive effects. Evidence suggests they provide little benefit, although any research study on vitamins has limitations, including how long patients were followed, the type of patients who were studied (young vs. old, male vs. female, etc), and how much of the supplement they received.

The studies did not examine the effects of herbal remedies such as ginko, St. Johns wart, and ginseng, which have been known to interact with medications and/or cause side effects.

The take away from the studies above is that vitamins have a neutral effect in otherwise healthy adults and have limited effect
on one’s heart and cognitive function.

Vitamins do not provide major benefits and, aside from beta-carotene, do not cause major harm. Healthy adults do not need to take them.

But, if one chooses to do so, there is little downside, aside from the impact on one’s wallet.