Eating soy isoflavones may affect menstruation, because soy isoflavones are also known as phytoestrogens, since they are estrogens, they may lead to thickening of the uterine lining, and during menstruation, the lining of the uterus sheds its blood, which will result in an increase in the amount of menstruation, and this is the effect of soy isoflavones on menstruation. Soy isoflavones although the health of the body appear favorable effects, there are diseases can not take soy isoflavones, such as uterine fibroids patients, uterine fibroids are estrogen-dependent tumors, if you take soy isoflavones will lead to uterine fibroids appear to accelerate the rate of growth, so don’t take. If you have breast hyperplasia, or endometrial cancer, cervical cancer patients, also can not eat soy isoflavones.