The Supplement Frenzy (cont.)

The Science Behind Antioxidants

Here's why people are scratching their heads. According to some studies, the pills seem to have worked wonders. For instance, vitamin E in daily doses of 400 to 800 international units (IUs) reduced the risk of heart attack by 77% in people with atherosclerosis who participated in the Cambridge Heart Antioxidant Study. (Harvard University scientists conducted the research and published their findings in the March 23, 1996 issue of the Lancet.)

But a study that tracked 2,545 women and 6,996 men aged 55 and older found that those who took vitamin E for five years suffered just as many strokes and heart attacks as those taking a placebo. (See the Jan. 20, 2000 issue of the New England Journal of Medicine.) Some research has even suggested that antioxidants may increase the risk for certain ailments. For instance, in a study published in the April 14, 1994 issue of the New England Journal of Medicine, researchers looked at more than 29,000 male smokers to see if vitamin E and beta-carotene could prevent disease. They found that large doses of beta-carotene appeared to raise the risk of lung cancer, while the vitamin E had no effect.

This spring a panel of top scientists, convened by the federal Institute of Medicine, weighed in. They concluded that we should be getting our antioxidants from the foods we eat, not popping handfuls of pills.

"There is not sufficient evidence that taking antioxidants in large doses will prevent chronic diseases such as heart disease," says Norman I. Krinsky, PhD, a Tufts University biochemist who chaired the panel. Still, the verdict could change, he says, if a raft of yet-to-be-completed studies turns up enough evidence to prove that supplements are worthwhile.

For now, then, here are the doses recommended by the panel:

  • Vitamin C, 75 milligrams a day for women, 90 for men, with an upper limit of 2,000 milligrams.
  • Vitamin E, 15 milligrams, with a max of 1,000 milligrams a day.
  • Selenium, 55 micrograms, with an upper limit of 400 micrograms a day.
  • No daily recommendation was given for beta-carotene.

Caution Warranted

The experts on the federal panel are not the only ones preaching caution about consuming large quantities of supplements. Mark S. Meskin, PhD, RD, an associate professor of food, nutrition, and consumer sciences at California State Polytechnic University in Pomona, Calif., is one of many nutrition experts who say the panel's recommendations reflect an honest appraisal of currently available research. He, too, advises consumers to skip the pills and focus on their diets. "My advice is to do what most Americans don't do -- eat fruits and vegetables," Meskin says. "Most don't meet the five-a-day [recommendation of the U.S. Department of Agriculture]."