whether soy does or doesn’t reduce the risk of breast cancer whether eating soy would have any effect on women who don’t have breast cancer or who have non-cancerous breast lesions; The researchers didn’t recommend that women avoid soy. But they did say that soy should be eaten in moderation. Examples of a single serving include: 1 cup of soy milk, 1/2 cup cooked soy beans, 1/2 cup of edamame, 1 ounce of soy nuts, or 1/3 cup of tofu. Soy and breast cancer. Because natural soy foods contain isoflavones, similar to estrogen, some people fear that soy may raise their risk for certain cancers.
Isoflavones in soybeans protect against breast cancer if consumed over a lifetime yet can aggravate cancer if started after cancer develops, an animal study shows. the Soy-Breast Cancer Author: Christopher Wanjek. Still, the study didn't show that isoflavones helped lower breast cancer risk. Another 2009 study, conducted in more than 5,000 Chinese women diagnosed with breast cancer, suggests that a diet rich in soy doesn't worsen prognosis in women diagnosed with breast cancer and may offer some protection against recurrence.