Nearly all American women are in danger of heart disease or stroke and should be more aggressive about lowering their risk — including asking their doctors about daily aspirin use, the American Heart Association said Monday in new guidelines.

It is the first time guidelines have urged all women to consider aspirin for preventing strokes, although specialists warn that it can cause ulcers and dangerous bleeding. They said it is probably not a good idea for young women with no big health problems.

"We do not want women to go to the drugstore and just start taking this themselves. It is critical that every woman talk to her doctor," said Dr. Lori Mosca, director of preventive cardiology at New York-Presbyterian Hospital and chair of the expert panel that wrote the guidelines.

The guidelines also advise daily exercise and less fat, and declare vitamins C and E, beta carotene and folic acid supplements worthless for preventing heart disease.

The guidelines were published in the journal Circulation with related studies on women's health, including one suggesting that hormone skin patches may be safer than pills for menopause symptoms.

In general, the guidelines aim to get women and doctors to focus on the long-term risk of high blood pressure, smoking, lack of exercise or being overweight — even if a woman's current health seems fine. Even a single risk factor at age 50 greatly raises the chance of heart disease or stroke later, and only about 10 percent of American women are free of these problems.

"We do not want women to wait until they develop symptoms to begin to take action," Mosca said.

The guidelines were drafted by dozens of groups worldwide, including the American Academy of Family Physicians and the U.S. government. Of the 33 people who wrote the advice, 13 have financial ties to heart drug makers, only three of them to a large degree.

"This is a really good gathering of evidence in women," after years of studies done mostly on men, said Dr. Sidney Smith, heart disease chief at the University of North Carolina at Chapel Hill and past heart association president.

The evidence shows that many more women than thought are at risk of heart disease and stroke — even those whose only weakness was failure to exercise every day. Heart disease is the leading killer of men and women worldwide.

The advice:

• Exercise — Get at least 30 minutes of moderately intense exercise on most and preferably all days, 60 to 90 minutes if you need to lose weight.

• Diet — Eat mostly fruits and vegetables, whole grain and high-fiber foods, fish at least twice a week, and little salt. Limit saturated fat to less than 10 percent of calories, 7 percent if possible, and trans fats to less than 1 percent. Limit alcohol to one drink or less a day.

• Don't smoke — Use nicotine replacement products if needed to stop.

• Weight — Keep body-mass index under 25.

• Supplements — Consider omega-3 fatty acids (fish oil) if you already have heart disease. Do not take extra folic acid or antioxidants like vitamins E, C and beta carotene, for heart disease prevention.

• Blood pressure, cholesterol — Keep under control, with medicine if needed. Keep LDL or bad cholesterol under 100 if at high risk of heart disease and under 70 if at very high 4isk.

• Aspirin — Daily use is already urged for women at high risk, and the guidelines now say the dose can go up to 325 milligrams. All other women should consider 81 milligram "baby aspirin" daily or 100 milligrams every other day for stroke prevention.