Two new studies of more than 120,000 men and women strongly suggest that supplements of vitamin E can significantly reduce the risk of disease and death from fat-clogged coronary arteries. But the researchers and other experts cautioned against rushing out to buy the vitamin supplements before further clinical trials confirm that they are beneficial and safe.
The studies, by researchers at the Harvard School of Public Health and Brigham and Women's Hospital in Boston, showed that initially healthy people with the highest daily intakes of vitamin E developed coronary disease at a rate about 40 percent lower than comparable men and women whose intake of this vitamin was lowest. The preventive effects of vitamin E occurred independently of any change in blood levels of cholesterol.
The greatest protection was found at levels of about 100 international units of vitamin E a day for more than two years. The Federal recommended daily allowance for vitamin E is 15 units, and most people consume fewer than 25 units from foods like vegetable oils, wheat germ, seeds, whole grains and nuts.
The researchers said vitamin E, as an antioxidant, might reduce heart disease by having an effect on low-density lipoprotein cholesterol, or LDL, the so-called bad cholesterol. Studies have shown that this type of cholesterol damages arteries primarily after it has been oxidized.
The new findings, which appear today in The New England Journal of Medicine, are some of the first to find health benefits from taking large-dose vitamin supplements. Most medical experts have viewed "megadoses" of vitamins as a popular remedy whose value is unproven.
Expert Urge Caution
While a person might conclude from the findings that it would be wise to take large doses of vitamin E supplements daily, their long-term safety has not been established. Experts say, however, many people take upward of 400 units of vitamin E supplements a day with no apparent harm.
Although experts expressed enthusiasm for the results, the researchers who conducted the studies and independent scientists cautioned against "leaping on the supplement bandwagon," as Dr. Claude L'Enfant, director of the National Heart, Lung and Blood Institute in Bethesda, Md., put it.
Dr. L'Enfant said in an interview that recommendations about taking vitamin E supplements must await the completion of more stringently designed clinical trials that clearly establish a benefit of vitamin E supplements and define any possible risks. Until such trials are completed, he said, researchers cannot be sure that vitamin E itself and not some other factor they neglected to account for was responsible for the reduction in coronary disease.
Overreliance on Vitamin
Experts also warned against relying on vitamin E for protection instead of making the more difficult changes in diet, exercise, smoking and other habits that are known to affect coronary risk.
Dr. Michael Brown of the University of Texas Southwestern Medical Center in Dallas said, "Vitamin E may help to minimize the toxicity of LDL cholesterol, but the real problem is that the LDL levels we accept as normal are really unnaturally high." Dr. Brown and his colleague, Dr. Joseph Goldstein, shared a Nobel Prize for elucidating how the body processes cholesterol.
Dr. Brown said that while people may view vitamin E as an innocuous substance, "the doses that seem protective are no longer in the category of vitamin, they are really drugs, and all drugs must be studied to determine their relative benefits and risks." He added: "The data are very suggestive but not definitive. We have to wait and see."
Still, Dr. Brown said, "the whole area is very exciting, and suggests that there may be a way to intervene therapeutically in coronary artery disease with antioxidants."
In an editorial in the medical journal, Dr. Daniel Steinberg of the University of California at San Diego emphasized that studies involving thousands of people have not been done to test the safety of large doses of vitamin E taken over decades. "It is still an unproven treatment," he wrote. "Let's hold the vitamin E," he added, until "large, long-term, double-blind clinical trials" are completed.
Such studies would involve giving some people, chosen at random, vitamin E and others a dummy pill, and are considered "double-blind" because neither the researchers nor the participants would know which patients were in which group.
Study Included 87,000 Women
One of the studies involved more than 87,000 women aged 34 to 59 who were free of known heart disease when the study began in 1980. The women, participants in a study directed by Dr. Frank Speizer of Brigham and Women's Hospital, were quizzed repeatedly about their diets and use of supplements. Over all there were 437 nonfatal heart attacks and 115 deaths caused by coronary disease over the next eight years.
Among the 15 percent of women studied who took vitamin E supplements of 100 or more units a day, the rate of heart attack was about 40 percent lower than among those who took no supplements. Other known coronary risk factors, including age, weight, smoking, high blood pressure and diabetes, did not account for the protective effect of vitamin E, the researchers reported.
The lead author of the report, Dr. Meir J. Stampfer of Brigham and Women's Hospital, said: "The women who took vitamin E supplements were not different in terms of their life style and general health status when compared to nonusers of supplements. This leads us to believe that vitamin E has a very strong protective effect."
He continued, "If clinical trials can confirm vitamin E's role, consumers should be cautioned about taking vitamin E as a substitute for addressing other proven risk factors, such as cigarette smoking and obesity."
Best Benefits With Long Use
The study in men, directed by Dr. Eric B. Rimm of the Harvard School of Public Health, involved nearly 40,000 health professionals aged 40 to 75 who in 1986 were free of diagnosed coronary heart disease and related disorders. During the next four years, 667 of the men developed coronary disease. But those who consumed more than 60 units of vitamin E a day were 36 percent less likely to develop heart disease than were the men who consumed less than 7.5 units a day.
And those who took supplements of 100 units or more a day for at least two years had a 37 percent lower risk than those who took no vitamin E supplements. The longer vitamin E was taken, the greater the benefit, the researchers found.
The two reports add credence to a recent discovery by Dr. Steinberg and others that low-density lipoprotein cholesterol damages arteries primarily after the cholesterol has been oxidized. Oxidation, the process that turns fats rancid, enables the cholesterol to become glued to artery walls and triggers several other damaging effects that raise a person's risk of suffering a heart attack.
Earlier studies in animals and one small study in people have indicated that various antioxidants can ward off the development of atherosclerosis, the blood-vessel damage that underlies the most common form of heart disease.
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