BREAST CANCER
Breast cancer has reached epidemic proportions in modern society, affecting 1 in 8 women. Breast cancer rates are substantially lower in countries where plant-centered diets are eaten. The protective effects of miso, tofu, and other soy products high in phytoestrogens and isoflavones are being intensively studied around the world. See Carrots, Dairy, Estrogen, Isoflavones, Menopause, Menstrual Disorders, Miso, Phytoestrogens, Sea Vegetables, Soy Foods, Tofu, Tempeh, Vegetables, Vegetarian Diet, Vitamin D, War-Restricted Diet, Women’s Health.
• Macrobiotic Diet Lessens Breast Cancer Risk - Macrobiotic and vegetarian women are less likely to develop breast cancer, researchers at New England Medical Center in Boston reported. The scientists found that macrobiotic and vegetarian women process estrogen differently from other women and eliminate it more quickly from their body. The study involved 45 pre- and postmenopausal women, about half of whom were macrobiotic and vegetarian and half nonvegetarian.
The women consumed about the same number of total calories. Although the vegetarian women took in only one third as much animal protein and animal fat, they excreted two to three times as much estrogen. High levels of estrogen have been associated with the development of breast cancer. “The difference in estrogen metabolism may explain the lower incidence of breast cancer in vegetarian women,” the study concluded.
Source: B. R. Goldin et al., “Effect of Diet on Excretion of Estrogens in Pre- and Postmenopausal Incidence of Breast Cancer in Vegetarian Women,” Cancer Research 41:3771-73, 1981.
• Miso Retards Tumors - In laboratory experiments, Japanese researchers reported that chemically-induced breast tumors in rats could be significantly decreased by feeding the animals a diet consisting of 10 percent miso.
Source: T. Gotoh et al., “Chemoprevention of N-nitroso-N-methylurea-Induced Rat Mammary Carcinogenesis by Soy Foods or Biochanin A,” Japanese Journal of Cancer Research 89(2)137-42, 1998.
• Kombu Decreases Risk of Breast Cancer - In an experiment at the Harvard School of Public Health, laboratory animals fed a control diet with 5 percent Laminaria (kombu), a brown sea vegetable, developed induced mammary cancer later than animals not fed seaweed.
“Seaweed has shown consistent antitumor activity in several in vivo animal tests,” the researchers concluded. “In extrapolating these results to the Japanese population, seaweed may be an important factor in explaining the low rates of certain cancers in Japan. Breast cancer shows a three-fold-lower rate among premenopausal Japanese women and a nine-fold-lower rate among postmenopausal women in Japan than reported for women in the United States. Since low levels of exposure to some toxic substances have been shown to be carcinogenic, then it may be that low levels of daily intake of food with antitumor properties may reduce cancer incidence.”
Source: J. Teas, M. L. Harbison, and R. S. Gelman, “Dietary Seaweed [Laminaria] and Mammary Carcinogenesis in Rats,” Cancer Research 44:2758-61, 1984.
• Tofu and Miso Protect Against Breast Cancer - In a study of the effects of soy products on female hormones, Japanese scientists reported that consumption of miso and tofu reduced production of estradiol in 50 healthy premenopausal women. “Our results suggest that the consumption of soy products lowers the risk of developing breast cancer risk modifying estrogen metabolism,” the researchers concluded.
Source: C. Nagata, “Decreased Serum Estradiol Concentration Associated with High Dietary Intake of Soy Products in Premenopausal Japanese Women,” Nutrition and Cancer 29(3):228-33, 1997.
• Asian Diet Helps Heal - A diet high in soy foods, vegetables, and fish oil may reduce the risk of breast cancer, according to a study conducted by the Jonsson Cancer Center at the University of California at Los Angeles. Dr. John Glaspy put 25 American women in remission from breast cancer on an Asian-style diet and reported that in three months on the diet the ratio of omega-3 in the women’s blood rose fivefold. The omega-3 to omega-6 ratio in breast fat is considered a major indicator of risk for this disease. Source: D. Bagga et al., “Dietary Modulation of Omega-3/Omega-6 Polyunsaturated Fatty Acid Ratios in Patients with Breast Cancer,” Journal of the National Cancer Institute 89(15):1123-31, 1997.
• Diet Lowers Risk for Hispanics - Hispanic women in the U.S. have the lowest mortality rate from breast cancer of all ethnic groups. University of Texas researchers reported that a study of 22 Hispanic women in the Houston area showed their mean intake of dietary fiber from grains, breads, beans, and vegetables was higher than other groups. “This may help explain the lower incidence of breast cancer among some Hispanic populations,” the study concluded.
Source: “Dietary Fiber, Hispanics, and Breast Cancer Risk?” Annals of the New York Academy of Science 837:524-36, 1997.
• Risks of Tamoxifen - Tamoxifen, a synthetic hormone that blocks estrogen, has been promoted for reducing the risk of breast cancer. However, it increases the risk of uterine cancer and blood clots. In a federal study, women who took tamoxifen had 45 percent fewer cases of breast cancer than controls, but over twice as much uterine cancer, nearly three times as many blood clots in the lungs, and 50 percent more blood clots in major veins.
For women age 50 or older, for every one thousand women treated with tamoxifen for five years, the drug might prevent 17 cases of invasive breast cancer, while causing 12 cases of endometrial cancer and 10 serious blood clots.
Source: Lawrence K. Altman, “Researchers Find the First Drug Known to Prevent Breast Cancer,” New York Times, April 7, 1998 and “Breast Cancer Breakthrough,” New York Times, April 8, 1998.