Foods and Breast Cancer: Strong Evidence Shows a Link
Can what you eat give you breast cancer? A mountain of evidence says yes, and is summarized in the November 1996 issue of Alternative Therapies in Health and Medicine, by PCRM’s Andrew Nicholson, M.D.
For years, researchers have studied the role of diet in breast cancer. By comparing different countries, researchers found strong links between high-fat diets and breast cancer risk. The disease is rare where the diets are very low in fat and where rice and other plant products are dietary staples. For example, before 1950, the rice-based Japanese diet drew less than 10 percent of its calories from fat. Breast cancer was exceedingly rare. But over the years, as Western influences have altered Japanese eating habits, breast cancer rates have climbed dramatically.
These international studies are just one line of evidence, however. Case-control studies are another research tool in which researchers compare diets of cancer patients (“cases”) with those of healthy women of similar age and background (“controls”). Such studies have also shown a link between fatty diets and higher risk of breast cancer, and even on cancer patient’s chances for survival. One study tracking Canadian breast cancer patients for ten years found that for every 5 percent increase in saturated fat in diets, the risk of dying of breast cancer shot up by 50 percent.
How does fat do its dirty work? Fats increase the amount of estrogen in the blood. In turn, this hormone stimulates breast cells in such a way that cancer is more likely to occur and is more aggressive. Fatty foods also lead to obesity which itself is linked to higher estrogen levels in the blood. Increased estrogen levels are also linked with early menarche (onset of first period), also a breast cancer risk factor.
Despite such evidence, doubts about the fat connection have persisted, fueled mainly by the results of a large study of nurses run by Harvard University in which researchers found no association between fatty diets and breast cancer rates.
Why the conflicting results? Unlike the populations examined in international studies, the nurses were a fairly homogeneous group, all eating fairly high-fat diets. No group in the study was following anything similar to a traditional Asian diet or other low-fat diet.
As important as it is to get fat off your plate, it’s just as important to pile on the vegetables and other healthful plant foods. Their fiber helps cut breast cancer risk by naturally decreasing estrogen levels. Plant foods are also rich in beta-carotene, vitamin C, and other vitamins which protect cells against damage. Unlike animal products, most plant foods have little fat and do not store up large amounts of pesticide residues.
A brisk morning walk—or any other regular exercise—also helps cut breast cancer risk. Skipping happy hour cocktails can do you a favor, too. Studies have shown that even one drink a day can increase your risk of breast cancer by 25 percent.
Starting today, you can boost your body’s chances of preventing and surviving breast cancer by giving it nature’s best ammo. Eat a variety of whole grain, vegetables, fruits, and beans every day. Limit your use of vegetable oil and alcohol, and skip tobacco and meat products. For delicious low-fat recipes, contact PCRM for our Vegetarian Starter Kit.
Nicholson A. Diet and the prevention and treatment of breast cancer. Alternative Therapies in Health and Medicine. 1996;2:32-38.