There's a lot of confusion on soy products and with good reason. First, fermented soy foods – such as miso, tempeh, and tofu – are safe to include in your diet. The fermentation process may destroy possible health-harming substances, such as the compounds that mimic the hormone estrogen. (If you have a family history or the gene that predisposes you to some types of cancer, these substances may exacerbate the situation.) Fermentation also maintains the blood thinning properties and healthy gut bacteria of soy foods, which make soy great for reducing cardiovascular risks.
What about menopause? Experts are still cautious about soy. There are some studies that show that indeed the phytoestrogens in soy may decrease menopause symptoms. However, others conclude the benefits do not outweigh the risks, particularly if you have a higher cancer risk.
Unfermented soy—mainly processed food like soy hot dogs and soy chips—has created the most intense debate. Experts say those with a history of some kinds of hormonally derived cancer should avoid this type of food. Others advise that everyone should approach these soy products with caution (i.e., some studies show a decrease in sperm count in men).
The general advice is to stick with fermented soy products, but no more than two servings per day, to get some health benefits.