Vitamin E appears to cut heart disease risk.

Daily consumption of vitamin E supplements appears to dramatically cut heart disease risk in middle-aged men and women, according to two large, ongoing studies of U.S. health professionals reported this week.

Biologically damaging oxidative reactions can foster degenerative changes that lead to many diseases associated with aging -- from cataracts and cancer initiation to arthritis and heart disease. Not surprisingly, researchers have spent much of the last decade investigating the potential of vitamin E, the body's premier antioxidant, to halt or slow aging-related changes in animals and cultured cells. Several medical teams have even used vitamin E to reduce signs of oxidation in people (SN: 8/1/92, p.76).

Few investigators, however, have attempted to gauge whether a surfeit of vitamin E protects against degenerative disease, as measured, for instance, by fewer heart attacks or less need for coronary bypass surgery. In the May 20 NEW ENGLAND JOURNAL OF MEDICINE, researchers at Brigham and Women's Hospital and the Harvard School of Public Health, both in Boston, report on a pair of large studies that do just that.

Questionnaires administered to participants in the Nurses' Health Study provide eight years of life-style and dietary information on 87,245 registered female nurses. A related Health Professionals Follow-up Study correlated diagnosed heart disease with four years' worth of similar data on 39,910 male veterinarians, dentists, pharmacists, optometrists, osteopathic physicians, and podiatrists.

In both studies, participants who consumed vitamin E supplements for at least two years faced about 40 percent lower risk of heart disease than individuals who derived vitamin E through diet only. Moreover, "it doesn't really seem to matter what the dose of that supplement is," notes epidemiologis Meir J. Stampfer, who coauthored both studies. Vitamin E capsules usually contain from 100 to 800 international units (IU) of tocopherol. By comparison, the recommended daily allowance of vitamin E is 10 IU for men and 8 IU for women, a level typical of the U.S. diet. Rich sources of vitamin E include vegetable oils, margarine, nuts, and whole grains.

"I expected vitamin E use would be a marker for a very healthy life-style," Stampfer says, and that accounting for such life-style factors "would explain away most of the vitamin's effect."

But that didn't happen. Adjusting for nonsmoking life-style, consumption of vitamin C -- another antioxidant -- and other factors thought to lower the risk of heart disease, diminished vitamin E's protective effect very little. The researchers did find that in men, carotenoids -- another class of antioxidants -- might also offer some protection against heart disease in smokers. Though the same might also prove true for women, Stampfer says his team has yet to analyze such data on the nurses.

In an editorial accompanying the two reports, Daniel Steinberg of the University of California, San Diego, notes these two huge studies strongly support animal data by his and other groups showing that oxidation of low-density lipoproteins (LDLs), the so-called "bad" lipoproteins, can play an important role in atherosclerosis. Indeed, "that's the most plausible kind of hypothesis to explain the new data," adds Ishwarlal Jialal of the University of Texas Southwestern Medical Center in Dallas.

But Jialal and Steinberg both caution against consumers stocking up on the vitamin. Why? Regardless of their size, epidemiologic studies cannot establish causality. Results from the randomized, placebo-controlled studies that can do that may be up to five years away.

Until then, Steinberg says, "let's hold the vitamin E."

Jialal acknowledges that's hard to do. "I don't take it," he notes. "But even I'm getting convinced [of its efficacy]."