Nutrition of soybeans
This post discusses the relationship between soy isoflavones and breast cancer. Soybeans are very nutritious. They are generally consumed as steamed edamame, tofu, soy milk, miso soup and tempeh. They provide all nine essential amino acids that human needs. Therefore, they are important source of protein for vegans and vegetarians. They are also a good source of omega-3 fatty acids, vitamin Bs and minerals. They also have higher levels of isoflavones than other legumes. The isoflavones found in soy are genistein, daidzein and glycitein. These isoflavones share similar chemical structure with estrogen, the female sex hormone in animals. They are called phytoestrogens (plant estrogen-like compound).
Soy isoflavones and breast cancer
Isoflavones are antioxidants, they can protect cells from oxidative damage especially with respect of DNA. Therefore, they can guard cells from developing into cancer cells. Furthermore, they have antiangiogenic (inhibiting formation of blood vessels) and anti-inflammatory properties. These properties will inhibit formation and growth of breast cancer.
The similarity in chemical structure with estrogen suggests that isoflavones may interact with estrogen receptors and imitate the action of estrogen. This raises the concern that soy consumption may lead to higher risk of breast cancer. However, studies showed that soy isoflavones decrease estrogen production and reduce growth of breast cancer cells. Clinical studies showed that there is an inversed correlation between soy product consumption and breast cancer death rate. In other words, higher consumption of soy products leads lower breast cancer death rate in women before and after menopause.
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