The recommendations to prevent all cancers apply to breast cancer. The advice includes: Quit smoking, reduce dietary fat, and eat fortifying food such as broccoli and Brussels sprouts. These cruciferous vegetables provide indoles, sulfur compounds that may also help spur cancer-fighting enzymes that may block or reduce cell damage, says Dr. Cohen.
In addition, early studies indicate that the following tips on the next few pages may decrease your risk of breast cancer.
Plan to breastfeed your baby. Women who breastfeed may have a slightly lower risk of breast cancer, some studies show. Possibly, breastfeeding interrupts ovulation and this lowers estrogen output. Another reason: "Breastfeeding may help breast cells become fully mature and thus less prone to mutations that can turn cancerous," says Dr. Zejewski.
Choose non-alcoholic drinks. Alcohol reduces the liver's ability to metabolize estrogen. (One of the liver's jobs is to reduce the potency of hormones and help to eliminate them from the body.) Even one to two drinks a day over your lifetime could spike your risk of breast cancer, some studies show. In one study, the amount of alcohol in three, 4-ounce glasses of wine more than tripled the amount of estrogen in women's bodies.
Don't sit there, move! In a widely publicized Norwegian study involving more than 25,000 women, those who exercised vigorously cut their cancer risk by more than a third compared to non-exercisers. [New England Journal of Medicine, May 1, 1997] If you have a desk job, exercise may be extra important. This year, Swedish researchers reported that women who had sedentary occupations during their reproductive years and lacked leisure-time physical activity had three times the risk of breast cancer compared to those physically most active both inside and outside the workplace [Cancer Causes Control, July, 2000]. One explanation is that exercise may stimulate the immune system or fight free radicals that corrode cells, suggests Dr. Cohen.
Piling on the pounds-especially around the waistline — is associated with increased breast cancer risk. [International Journal of Obesity and Related Metabolic Disorders, May 2000]. One study showed that women in their 50's who have gained more than 20 pounds had twice the risk of breast cancer. [Journal of the National Cancer Institute, 1996 88:650-60]. Body fat may convert adrenal hormones to estrogen after menopause, according to Katrina Claghorn, R.D., oncology dietician at the University of Pennsylvania Comprehensive Cancer Center in Philadelphia. Losing weight before menopause, however, lowers risk.
Most people get a meager 12 grams of fiber a day. Our studies showed that doubling that amount could reduce breast cancer," says Dr. Cohen. The reason? A diet chock full of whole grains, fruits and vegetables supplies both soluble and insoluble fiber (the type that doesn't dissolve in the body) which binds to estrogen and escorts it out of the body. Fiber may also enhance bacteria that metabolize estrogen. Wheat bran also contains phytic acid and lignans shown to block the growth of mammary cancer in the lab studies. A bowl of cereal will provide one quarter of your quota.
From apples to zucchini, plant foods provide phytochemicals which all have different protective effects against cancer. Red peppers and strawberries, for example, are rich in vitamin C, an antioxidant that blocks the formation of harmful free radicals that corrode cells, which leads to cancer. Postmenopausal women with a high intake of vitamin C may reduce risk of cancer by 16 percent, one early study suggests. Citrus bioflavonoids, found in the peel of oranges and tangerines, and reserterol in grape peels may also protect against breast cancer.
"Population studies show that people who consumed flavonoids over their entire lives have lower incidences of breast cancer," says Patricia Murphy, Ph.D., professor in food science and human nutrition research at Iowa State University. Flavonoids may have weakly estrogenic effects, meaning they attach to estrogen receptors throughout the body, thus blocking the attachment of one's own estrogens. The most widely studied flavonoid is soy. The soybean's isoflavones (most notably genistein) has been shown in lab studies to inhibit the growth of breast tumors.
While five daily servings of fruits and vegetables is the minimum for good health, doubling that amount may be more protective against breast cancer, according to a pilot study at the AMC Cancer Research Center in Lakewood, Colorado sponsored by the American Institute for Cancer Research (ACIR) in Washington. Blood samples taken from 28 women at high risk for breast cancer who ate 10 or more servings of vegetables and fruits daily for two weeks showed reduced damage to the DNA by nearly more than 20 percent in just two weeks. "The key is quantity, variety and eating the whole — not processed — food," says Melanie Polk, R.D., AICR's director of nutrition education. Strawberry jam on your toast doesn't count. But juices and frozen foods do.
Salmon, mackerel and other cold water fish contain Omega-3s, the same fatty acids that reduce blood fats and protect against heart disease may also protect against breast tumors, according to Claghorn. Other good sources of the omega-3 fatty acids are flaxseeds, soy and walnuts.
Women who consumed three fourths of a tablespoon of monounsaturated fat could cut their breast cancer risk in half, according to a Swedish study involving 60,000 women. [Archives of Internal Medicine Jan. 12, 1998]. Possibly, these oils may help to balance fats in the body, which affects estrogen levels, says Claghorn. Substitute monos for margarine, butter and other trans-fatty acids (most fats in processed foods) and saturated fat sources. And eat mono-rich avocados and almonds.
Those tasty black marks on your burger could spell danger, early investigations show. [Cancer, August 1, 1994]. The fat laced throughout animal protein (even lean cuts), when heated to high temperatures, forms heterocyclic amines in the body, which may prompt breast tumor formation, explains Claghorn.
Women should limit conventional hormone replacement therapy to five years. After menopause, taking estrogen alone for more than four years increases the risk for breast cancer by 20 percent. But the most recent studies show that breast cancer risk increases by 40 percent among women who take the combination estrogen/progestin (the term for synthetic progesterone) hormone replacement therapy than for non-users. [Journal of the American Medical Association, January 26, 2000]. Taking HRT for less than five years does not increase the risk.
See the next page for more information about breast cancer and women's health.
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