And a daily aspirin didn't prevent heart disease in middle-aged diabetics, according to a study that counters recommendations by the American Diabetes Association.

The findings were reported Sunday at an American Heart Association conference in New Orleans. Results also were published online by the Journal of the American Medical Association.

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

Howard had no role in the research but reviewed and discussed it at the conference. About 12 percent of Americans take supplements of C and E despite growing evidence that these antioxidants do not prevent heart disease and might even be harmful.

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

As for vitamin C, some research suggests it might 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 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.

But 39 men taking vitamin E suffered bleeding strokes compared with 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.

"In these hard economic times, maybe we can save some money by not buying these supplements," she said.

A second study found that vitamins B-12 and B-9, folic acid, did not prevent heart disease either, supporting the results of previous trials.

That study involved more than 12,000 heart attack survivors and was led by Dr. Jane Armitage of the University of Oxford in England. It showed the folic acid supplements are safe, with no excess risk of cancer or other side effects.

The aspirin trial was reported by Japanese scientists.

Aspirin prevents heart attacks and strokes for people who have heart disease, past studies have shown. It is often recommended in an effort to keep disease from developing, but scientists found no clear evidence it is helpful.

People taking aspirin were just as likely to develop plaque buildup in their arteries, causing heart attacks, strokes and clots in the legs as those who didn't get a low-dose tablet every day. There was some evidence of benefit for patients 65 and older and in preventing deaths from heart attacks and strokes, though neither was the main goal of the study, the researchers said.

Patients in the aspirin study, which enrolled 2,539 Type-2 diabetics whose age averaged 65, also were more likely to develop bleeding ulcers and retinal hemorrhage, and four needed blood transfusions.

None of the participants had a history of heart disease risk. Patients were given either 81 milligrams or 100 milligrams of aspirin or nonaspirin medicine, with a median follow-up after nearly 4.5 years. The researchers were led by Hisao Ogawa, from Kumamoto University's Graduate School of Medical Sciences.