You're delving into the unknown. We don't know what the effects are. Dr. Robert Marcus, professor of medicine at Stanford and director of the Aging Study Unit at the Palo Alto Veterans Affairs Medical Center, says the jury is out on how soy effects some areas of the body. For instance, he says, some studies show certain isoflavones in soy can help prevent breast cancer. It's a very complicated question and the answer is not there.
Some studies show estrogenlike effects on certain tissues.
The rap is people in Asia who take a lot of soy have less breast cancer. But there is a leap of faith there. A year later, soy got another boost with news that women in some Asian countries, notably Japan, who typically eat a diet much higher in soy than most American women have breast cancer rates about one- quarter lower than women in the United States. In 1999, the U.S. Food and Drug Administration allowed food manufacturers whose products contain at least 6.25 grams of soy protein per serving to promote as it as reducing heart disease. In addition to tofu, tempeh and miso, several new processed foods like meatless burgers, soup mixes and cereals have enough soy to meet the federal guidelines.