VITAMIN OVERLOAD?

By Christine Gorman

Does beta-carotene cause cancer? Will vitamin B6 damage the nerves? Can calcium weaken the kidneys? These were some of the unsettling questions raised by a story on the front page of the New York Times last week that had vitamin takers across the U.S. wondering if they--or their children--were swallowing too much of a good thing.

It has long been an article of faith among health-conscious Americans that extra doses of vitamin and mineral supplements can cover a multitude of dietary sins. So it seemed like heresy last week when Jane Brody, the Times' respected health columnist, questioned the value of those supplements and the quantities they are being taken in. "There is scant evidence that vitamin and mineral supplements are beneficial [for most people]," she wrote. "Consumers are, in effect, volunteering for a vast largely unregulated experiment."

Brody's warning comes in the midst of a vitamin boom. As her article noted, Americans have more than doubled their spending on vitamins and minerals in the past six years, from $3 billion in 1990 to $6.5 billion in 1996. They have also ratcheted up the dosages they take, gulping down supplements at 10, 50, even 100 times the daily recommended levels. One-A-Day and other multivitamin products were originally designed to prevent such centuries-old nutritional deficiencies as scurvy and beriberi. But now the same micronutrients are being taken in megadoses--in effect, as drugs--to prevent or treat a broad range of illnesses, including psoriasis, tendinitis, cancer and heart disease.

Why did Brody rain on this pill-popping parade? "My major hope was to awaken the public to the fact that vitamins and other supplements are not always innocent," she says. "I'm often asked by people, 'Should I take this vitamin?' 'Am I taking enough of that?' Even 'Can I take vitamins instead of antibiotics?'"

What bothers Brody is that there is precious little scientific evidence to support the more ambitious claims being made for vitamins, and what evidence there is is often far from definitive. The quantity of vitamins that an adult or a child should consume depends on many factors, including age, sex and health condition. Making matters more complicated, nutrients tend to interact with one another. For example, vitamin C is supposed to act as an antioxidant, preventing damage to the cells. But that same vitamin, in the presence of iron, can act as a pro-oxidant, causing, rather than preventing, cellular damage, according to Dr. Meir Stampfer, professor of epidemiology and nutrition at the Harvard School of Public Health.

Nor do scientists always agree. "Folic acid is a perfect example," says Rima Apple, a historian at the University of Wisconsin at Madison and author of Vitamania: Vitamins in American Culture. In 1989 the recommended dietary allowance for folic acid was cut from 400 micrograms for all adults to 200 micrograms for men and 180 micrograms for women, because that was the lowest amount that would stave off a nutritional deficiency. At the same time, however, new studies were showing that higher doses of folic acid could prevent crippling birth defects during pregnancy and ward off strokes and heart attacks in older adults. "The recommended levels came down," Apple notes, "just as the evidence for taking higher doses was coming in."

No supplement has been more battered by conflicting reports than beta-carotene, a vitamin found in fruits, carrots, spinach and other dark green leafy vegetables. Studies in the 1980s showed that people who consume a lot of beta-carotene-rich foods have a marked decrease in their risk of cancer. Those studies set off a beta-carotene craze and created a huge market for beta-carotene supplements. It wasn't until the late 1980s that researchers from Finland and the U.S. decided to test the proposition that beta-carotene in pill form could protect smokers from cancer. The results were not what they expected. As the researchers reported in 1994 and 1996, smokers who took the beta-carotene pills actually suffered an increase in cancer rates. "Those studies sent shock waves through the vitamin community," says Bonnie Liebman, director of nutrition at the Center for Science in the Public Interest in Washington. "It showed just how little we know and how hesitant we should be before issuing recommendations."

Even Brody takes 400 units of vitamin E and 200 mg of C every day, however, just to be safe. She's not saying that supplements are bad, or that there's any danger in giving kids their Flintstone vitamins. Her concern is that too many people are taking huge doses without much evidence that they will do any good and without considering the harm they might cause. "If you have reason to believe that you are shortchanged on a single nutrient, you have to know what the risks are," she says. "That may require a consultation with a professional nutritionist, not a conversation with your neighbor, a chiropractor or a health-food-store employee." Now if only common sense came in a pill.