Phytoestrogens are estrogen-like compounds found in some plants. Women often consume food or supplements that contain phytoestrogens to ease the signs and symptoms that come with menopause including hot flashes, breast tenderness, and the increase in bone loss. There have been conflicting results as to whether phytoestrogens can improve or worsen the risk of developing breast cancer.
Sources of Phytoestrogens
Phytoestrogens can be found in some legumes, such as soy, peanuts, chick peas, alfalfa, fava beans and red clover. Soy beans and soy products like tofu, soy burgers and soy milk are also excellent sources of phytoestrogens. Red clover is part of the legume family and has historically been used for cancer and certain respiratory disorders. According to a June 2008 research review published in the "Nutrition Journal," it seems unlikely that isoflavone consumption at dietary levels of less than 100 mg per day will elicit adverse breast cancer-promoting effects in healthy women or breast cancer survivors not undergoing active treatment.
How Phytoestrogens Work
There are several ways that phytoestrogens can work in the body. Mimicking estrogen, phytoestrogens may either have the same effects as estrogen or block estrogen's effects. When phytoestrogens act differently from estrogen, they can affect communication pathways between cells, prevent the formation of blood vessels to tumors, or alter the processing of DNA for cell multiplication. Because phytoestrogens compete for the same receptors as estrogen, they may also block estrogen's effects when taken at high doses. Not enough research is available to determine what truly occurs in the body with the consumption of phytoestrogens, according to the Cornell University website.
Long-Term Effects of Phytoestrogens and Breast Cancer
The effects of long-term use of phytoestrogens have not been established and research is controversial. However, higher exposure to estrogens over a lifetime is linked with increased breast cancer risk. According to the Cornell University website, almost half the studies performed have reported no effect of soy on breast cancer risk, while some animal studies indicate that soy phytoestrogens can decrease breast cancer formation in rats. However, all studies suggest that soy phytoestrogens can behave like estrogen and potentially increase breast cancer risk. Additionally, phytoestrogen supplements have caused breast tissue growth in animals and healthy women.
Dangers of Phytoestrogens
According to the National Center for Complementary and Alternative Medicine, women who are at an increased risk of developing diseases that are affected by the hormone estrogen, such as breast, uterine or ovarian cancer, endometriosis or uterine fibroids, should use caution in consuming phytoestrogens, as they may aggravate these conditions. Also, if you are taking drugs such as birth control pills, MHT, or selective estrogen receptor modulators, your estrogen levels may be increased as a result. Discuss the use of soy, phytoestrogen-containing products or supplements with your doctor before consuming.
References
- National Center for Complementary and Alternative Medicine: Red Clover; July 2010
- National Center for Complementary and Alternative Medicine; Menopausal Symptoms and CAM; January 2008
- Medline Plus; Red Clover; November 2010
- National Center for Complementary and Alternative Medicine: Soy; July 2010
- Cornell University; Phytoestrogens and Breast Cancer; July 2001
- "Nutrition Journal"; Soy Isoflavones, Estrogen Therapy, and Breast Cancer Risk: Analysis and Commentary; Mark J. Messina and Charles E. Wood; June 2008
