"These findings give us some confidence that dietary soy doesn't promote uterine cancer and, in fact, may offer a protective effect in some cases," said Cline, who summarized the research studies today in Chicago at the 6th International Symposium on the Role of Soy in Preventing and Treating Chronic Disease.
Cline said there has been much debate about whether high levels of dietary soy are safe for postmenopausal women. Soy products are sometimes sold as a natural alternative to traditional estrogen therapy, which does increase the risk of endometrial cancer. The formulation of hormone therapy designed to address that risk a combination of estrogen and progesterone has been shown to increase risk of breast cancer.
Soy and some other plants contain estrogen-like compounds called isoflavones or phytoestrogens. These plant estrogens are thousands of times weaker than the estrogen produced by the body, but may be present in much higher concentrations in the blood. Researchers are not certain how plant estrogens and the estrogen produced by the body, or given in pills, act together. One theory is that the plant estrogens bind to cells that have estrogen receptors, such as breast and uterine tissue, and block the effects of the estrogen pills or estrogen made by the body.
Evidence about the safety of soy isoflavones has been mixed. It is known that populations that typically consume diets high in soy have much lower rates of uterine cancer. On the other hand, some laboratory studies in animals have shown that soy isoflavones can stimulate the growth of uterine cells, which is a mar
Contact: Karen Richardson
Wake Forest University Baptist Medical Center