BETA CAROTENE PILLS DON'T HELP, MAY HURT, NEW STUDIES INDICATE.

Byline: Gina Kolata The New York Times

Two large studies have found that, contrary to the beliefs or hopes of the millions of Americans who take it, beta carotene, a vigorously promoted vitamin supplement, is completely ineffective in preventing cancer or heart disease. One of the studies found that it might even be harmful to some people.

Federal health officials said they hoped this would spell the end of the beta carotene fad. The idea that a simple supplement capsule might fend off cancer and other diseases, they said, has simply proved too good to be true.

"With clearly no benefit and even a hint of possible harm, I can see no reason that an individual should take beta carotene," said Dr. Richard Klausner, director of the National Cancer Institute. The institute financed both studies.

Beta carotene occurs naturally in fruits and vegetables and is converted to vitamin A in the body. The cancer institute recommends that, rather than rely on supplements, people eat low-fat diets abundant in fruits and vegetables, whose hundreds of substances combined might foster the disease protection that has been sought in beta carotene.

Americans spend $3.5 billion a year on vitamin and mineral supplements, said Dr. Annette Dickinson, the director of science and regulatory affairs at the Council for Responsible Nutrition, a trade association of supplement manufacturers.

But the health claims for many of these supplements have not been verified by rigorous scientific investigation, and the Food and Drug Administration is not empowered to regulate claims that manufacturers make in most of the advertising and promotional brochures in which they extol the supplements' potential health benefits.

One of the beta carotene studies, the Physicians' Health Study, involved 22,071 doctors who were randomly assigned to take 50 milligrams of beta carotene or a dummy pill every other day. The study ended Dec. 31, after 12 years, with the conclusion that beta carotene supplements did not protect against cancer or heart disease.

The other study, the Beta Carotene and Retinol Efficacy Trial, or CARET, tested both beta carotene, in a dose of 30 milligrams a day, and vitamin A, in a daily dose of 25,000 international units. The 18,314 participants in this study took beta carotene, vitamin A, both, or a placebo.

Preliminary studies had hinted that beta carotene might be especially effective in preventing lung cancer, and all the subjects in the CARET study were at high risk for lung cancer because they smoked or had worked with asbestos.

The study was halted Jan. 10 - 21 months ahead of schedule - when investigators concluded not only that the vitamins failed to help, but also that they might be harmful. The rate of death from lung cancer was 28 percent higher among the participants who had taken the supplements than among those who had taken the placebo, and the rate of death from heart disease was 17 percent higher.

The reason for these increases is unclear, and the increases were too few to be considered statistically significant. But they were nonetheless worrisome.

The two studies came after a Finnish study of 29,133 men who were smokers. That study, published in 1994, found a slight increase in the death rate among those who had taken beta carotene. But some critics of the research said the beta carotene dose, 20 milligrams a day, had been too low.

To underscore the importance of the new findings, Klausner announced them at a news conference Thursday at the National Cancer Institute in Bethesda, Md., without waiting for the usual publication in a medical journal.