Breast Cancer: Soy Protects Against Relapse
December 10th 2009 -
Tofu, soy milk and soybeans to reduce the risk of relapse in breast cancer patients. Also, the probability of dying from the malignancy, goes back with increasing consumption. This resulted in an extensive study of the Shanghai Institute of Preventive Medicine and Vanderbilt University.
The international team interviewed more than 5,000 20 – to 75-year-old women who were being treated for breast cancer. The patients were asked to indicate which foods they take in what amounts to her. In addition to soy, the researchers also asked for meat, fish and vegetable consumption. In the next four years, 444 women died from the effects of the disease, 534 more experienced a relapse (recurrence). The more soy foods the participants ate, the better they were protected from late effects. The effect increased up to a limit of 11 g soy protein per day or 40 mg of isoflavones contained therein, after which it remained constant and the protective effect was once again possible. Tofu contains almost 9 grams soy protein per 100 g total weight.
“It is important that we have examined the diet with soy products, and not the intake of soy capsules as dietary supplements,” notes Xiao Ou Shu, director of the study. The capsules often contain only purified isoflavones in soy milk or tofu still last for ANYWHERE other nutrients. Whether isoflavones alone also show the protective effect was therefore not clear as Shu.
Isoflavones compete with estrogen for the estrogen receptors on cancer and other cells – thus there displace the endogenous hormone. In addition, they reduce the production of estrogen and ensure that they are removing the steroid hormones. The combination of these properties could be responsible for the positive effect on breast cancer patients, suggest the study authors. Other components of soy such as folic acid, protein, calcium and dietary fiber may also help.
The protective action unfolded in front of both women after the menopause. And it did not matter whether the breast cancer sensitive to estrogen response or not (estrogen receptor status). A soy-rich diet had no effect on the treatment with tamoxifen, which had been feared because of previous studies with tamoxifen and isoflavones.
Tags: estrogen receptor, isoflavones, soy protein, steroid hormones, tamoxifen, tofu
