Are Vitamins a Superstition?

First a confession: I have been taking big doses of various vitamins for a number of years. Of course, finding and fixing vitamin deficiency diseases—ricketts, beriberi, scurvy—was one of the great medical triumphs of the last century. But is too much of a good thing actually bad for us? 

Over the past few years, researchers have launched a number of studies seeking to find out if taking high doses of various vitamins might produce beneficial health effects. The evidence has been slowly piling up that any good that megadoses of vitamins may do is more than offset by harms. For example, a 2004 study of vitamin E supplement showed that megadoses actually increased the risk of death. This was followed by a number of other studies that came to the same conclusion. I stopped taking megadoses of vitamin E. 

The latest blow to the hopes of us that taking vitamins might improve our health comes in the form of two new studies reported this week. As the New York Times notes: 

A study of vitamin E and selenium use among 35,000 men found that the vitamin users had a slightly higher risk of developing prostate cancer, according to a report published Tuesday in The Journal of the American Medical Association. A separate study of 38,000 women in Iowa found a higher risk of dying during a 19-year period among older women who used multivitamins and other supplements compared with women who did not, according to a new report in The Archives of Internal Medicine.

The findings are the latest in a series of disappointing research results showing that high doses of vitamins are not helpful in warding off disease.

One finding is that men in the prostate cancer study who took vitamin E were slightly more likely to get prostate cancer than those who did not. The second study involved thousands of older women and found that the use of multivitamins, vitamin B6, folic acid, iron, magnesium, zinc and copper were all associated with increased risk of death.

A good definition of a superstition is "a belief or practice resulting from ignorance, fear of the unknown, trust in magic or chance, or a false conception of causation." As data accumulate, taking megadoses of vitamins looks more and more like a superstition.