Eat foods high in fiber. Try to increase the amount of fiber you eat to between 20 and 30 grams daily — about twice the amount in an average American diet. Among its many health benefits, fiber helps reduce the amount of circulating estrogen in your body. Foods high in fiber include fresh fruits and vegetables and whole grains.

Eat plenty of fruits and vegetables. Fruits and vegetables contain vitamins, minerals, and antioxidants that may protect you from cancer. Try to eat five or more servings of fruits and vegetables every day.

Include soy foods in your diet. Some studies suggest that substances in soy may inhibit the development and growth of cancer cells. One is the isoflavone genistein, which seems to bind to estrogen receptor sites, blocking the activity of estrogen in your body. Good sources of soy include tofu and soy milk.

Limit fat in your diet. No clear link between dietary fat and breast cancer exists. But reducing the amount of fat in your diet decreases your risk of some other cancers as well as diabetes, cardiovascular disease and stroke. It also helps you maintain a healthy weight, which does reduce your risk of breast cancer. It's a good idea to limit your fat intake to less than 30 percent of your daily calories, with no more than 10 percent coming from saturated fats.

Limit alcohol. Try to limit your alcohol intake to no more than one drink a day. A recent study suggests that taking folic acid might help reduce the risk of breast cancer in women who consume moderate amounts of alcohol.

Stay physically active. The Nurses' Health Study, a long-term study of more than 120,000 female nurses, found that women who exercised for at least 1 hour a day reduced their breast cancer risk by 18 percent. Those who exercised for 30 minutes every day reduced their risk by 10 percent. Walking was found to be as effective as more vigorous types of exercise. A good place to start is to aim for at least 30 minutes of exercise on most days. If you haven't been active before, start out slowly and work up gradually. Try to include weight-bearing exercises such as walking, jogging or dancing. These have the added benefit of keeping your bones strong.

Maintain a healthy weight. There is a clear link between weighing more than is healthy for you and breast cancer. The risk is greatest if you gain weight later in life, especially after menopause.

Avoid exposure to pesticides. The molecular structure of some pesticides closely resembles that of estrogen. This means they may attach to receptor sites in your body. Although studies have not found a definite link between most pesticides and breast cancer, it is known that women with elevated levels of pesticides in their breast tissue have a greater breast cancer risk.

If you're at high risk, ask your doctor about tamoxifen. The hormonal drug tamoxifen may reduce the risk of breast cancer in women who are at high risk of the disease. The largest study of tamoxifen to date showed that tamoxifen decreased the risk of developing breast cancer by about 50 percent during the 5 years of the study, although the risk of dying from the disease was not reduced. On the other hand, two European studies showed no reduction in the chance of developing breast cancer among women using tamoxifen. In addition, tamoxifen has other risks, including an increased chance of developing endometrial cancer, blood clots and cataracts. Only women at high risk of breast cancer are candidates for tamoxifen. Even then, you'll need to weigh the costs and benefits carefully with your doctor.

A large-scale study is currently under way to determine whether the drug raloxifene (Evista) might also reduce the incidence of breast cancer in high-risk women. Like tamoxifen, raloxifene belongs to a class of drugs known as selective estrogen receptor modulators (SERMs). These drugs are sometimes referred to as designer estrogens because they mimic the action of estrogen in some places — your cardiovascular and skeletal systems, for instance — but not in others — breast and uterine tissue, for example. Further study is needed to evaluate the long-term safety and effectiveness of raloxifene and other SERMs.