Beta Carotene May Reduce Stroke, Heart Attack Risks : Research: Findings come from a study involving 333 men over a period of six years. The same team earlier reported on benefits of aspirin.

A research team has discovered that beta carotene--the substance found in many yellow and orange fruits and vegetables--might reduce the incidence of strokes and heart attacks in people who have cardiovascular disease.

Among 333 men who had evidence of cardiovascular disease, those taking beta carotene over six years had half as many incidents of stroke, heart attack, sudden cardiac death or surgery to open or bypass clogged coronary arteries as those taking a placebo, said Dr. Charles Hennekens, senior author of the research.

The same research team reported previously that aspirin can help prevent heart attacks. But while aspirin has become an important prevention strategy for people at high risk of heart attack, researchers say the findings on beta carotene are preliminary and must be confirmed before the substance can be recommended for heart patients.

Beta carotene probably has a more modest effect on heart disease than aspirin, Hennekens said. But, he noted, among the men in the study who took both aspirin and beta carotene, none experienced heart attacks.

It is not known whether beta carotene has any value in preventing the onset of cardiovascular disease, said Hennekens, of Brigham and Women’s Hospital and Harvard Medical School. Beta carotene is found in high quantities in carrots, sweet potatoes, apricots, peaches and cantaloupes.

The research, part of the long-term Physicians’ Health Study involving 22,000 male doctors, was presented Tuesday in Dallas at a scientific conference sponsored by the American Heart Assn.

“We have the first evidence, not a consistent body of evidence,” said Hennekens. “It’s a very preliminary result, and it’s a result we want to communicate to other researchers. We don’t have any message to the general public.”

The potential connection between beta carotene and heart disease was made somewhat by happenstance. The study was originally designed to explore whether aspirin helps prevent heart disease and whether beta carotene helps prevent cancer.

But, after the study began, basic laboratory research revealed that beta carotene might have some effect on heart disease.

The aspirin component of the study was ended in January, 1988, after only four years, because data showed a 44% reduction in risk of a first heart attack among doctors taking one aspirin every other day, and researchers felt the therapy should be extended immediately to anyone who could benefit from it.

The beta carotene arm of the study continued, however, with physicians assigned at random to receive a capsule of 50 milligrams of beta carotene every other day or a placebo. Neither the researchers nor the study participants knew which substance they were taking.

The study revealed 10 heart attacks among men who took beta carotene compared to 17 among men who took a placebo. Consumption of beta carotene does not appear to have side effects. The data also suggests that beta carotene might complement aspirin in preventing heart attacks: none of the men who took both beta carotene and aspirin had heart attacks.

While aspirin is thought to prevent heart attacks by reducing blood clotting, scientists have shown that beta carotene, a primary building block of Vitamin A, is a powerful antioxidant. Antioxidants are compounds that counteract the effects of oxygen-free radicals in blood, which can damage proteins and lipids, or fats.

Researchers suspect that low-density lipoprotein cholesterol, the so-called bad cholesterol, combines with oxygen present in high concentrations in the blood to become extremely toxic and accelerate the thickening and blockage of arteries.

“If a drug (such as beta carotene) would prevent the oxidation of LDL cholesterol, then it might slow the progress of atherosclerosis,” said Dr. J. Michael Gaziano, a cardiology fellow at Brigham and Women’s Hospital in Boston, who presented the findings Tuesday.

But Hennekens recommended against taking high-dose beta carotene supplements to reduce the risk of cardiovascular problems because, he says, it might lead people to ignore other protective measures.

“My concern about it at this point, from the standpoint of the general public, is that we have a very preliminary finding,” he said. “The downside of (taking beta carotene) is that someone with chronic unstable angina or who smokes or who has had bypass surgery or who has high blood pressure, might want to take beta carotene to lower their risk instead of doing other things that we know will work,” such as exercising, eating healthful foods and abstaining from smoking.

Data from the other 22,000 participants in the Physicians’ study has not been analyzed to show if beta carotene helps prevent cardiovascular disease in healthy people. The National Institutes of Health has agreed to continue funding the study to answer remaining questions on the preventive value of beta carotene.

The National Cancer Institute recommends that people consume foods rich in beta carotene on the unproven theory that it might prevent cancer.