NEW ORLEANS — Vitamins C and E — pills taken by millions of Americans — do nothing to prevent heart disease in men, one of the largest and longest studies of these supplements has found.

Vitamin E even appeared to raise the risk of bleeding strokes, a danger seen in at least one earlier study.

Besides questioning whether vitamins help, "we have to worry about potential harm," said Barbara Howard, a nutrition scientist at MedStar Research Institute of Hyattsville, Md.

She has no role in the research but reviewed and discussed it Sunday at an American Heart Association conference. Results also were published online by the Journal of the American Medical Association.

About 12 percent of Americans take supplements of C and E despite growing evidence that these antioxidants do not prevent heart disease and may even be harmful.

Male smokers taking vitamin E had a higher rate of bleeding strokes in a previous study, and several others found no benefit for heart health.

As for vitamin C, some research suggests it may aid cancer, not fight it. A previous study in women at high risk of heart problems found it did not prevent heart attacks.

Few long-term studies have been done. The new one is the Physicians Health Study, led by Drs. Howard Sesso and J. Michael Gaziano of Harvard-affiliated Brigham and Women's Hospital in Boston.

It involved 14,641 male doctors, 50 or older, including 5 percent who had heart disease at the time the study started in 1997. They were put into four groups and given either vitamin E, vitamin C, both, or dummy pills. The dose of E was 400 international units every other day; C was 500 milligrams daily.

After an average of eight years, no difference was seen in the rates of heart attack, stroke or heart-related deaths among the groups.

However, 39 men taking E suffered bleeding strokes versus only 23 of the others, which works out to a 74 percent greater risk for vitamin-takers.

The study was funded by the National Institutes of Health and several vitamin makers. Results were so clear that they would be unlikely to change if the study were done in women, minorities, or with different formulations of the vitamins, Howard said.

NEW ORLEANS — People with low cholesterol and no big risk for heart disease had dramatically lower rates of heart attacks, death and stroke if they took the cholesterol pill Crestor, a large study found.The results, reported Sunday at an American Heart Association conference, were hailed as a watershed event in heart disease prevention. Doctors said the study might lead as many as 7 million more Americans to consider taking cholesterol-lowering statin drugs, sold as Crestor, Lipitor, Zocor or in generic form."This takes prevention to a whole new level, because it applies to patients who we now wouldn't have any evidence to treat," said Dr. W. Douglas Weaver, president of the American College of Cardiology.The study also gives the best evidence yet for using a new test to identify people who may need treatment, according to a statement from Dr. Elizabeth Nabel, director of the National Heart, Lung and Blood Institute. The research will be considered by experts reviewing current guidelines.However, some doctors urged caution. Crestor gave clear benefit in the study, but so few heart attacks and deaths occurred among these low-risk people that treating everyone like them in the United States could cost up to $9 billion a year — "a difficult sell," one expert said.