This never posed a problem to me until recently after I received an email from a previous co-worker in Toronto.  In her email, she shared  a story regarding to a girl who had lots of health problem caused by soy bean products.  The girl has paid lots of attention to what she eats, been working out hard to keep in shape.  A few years after she has been eating lots of soy products as replacement of meat in order to get protein.  Tumors and abnormal cells start to appear in different body parts. First,  thyroid, she got that removed. Second, ovary,  then she got the whole female productive system removed.  Then breasts were removed as well.  So she started to question herself and doctors why all these had happened to her since she has been eating healthy and excercise regularly.  Meanwhile, she started to search information online about soy beans.  Then she found that quite a few other females posted their similar stories. They all pointed out that soybean caused the problems for them.  After reading this email, I start to feel curious because I never thought soy beans can cause health problems for human. That is not the way we have been told. We have been told that soy beans protect us from heart disease, cancer, osteoporosis and the discomforts of menopause. And actually my graduate study is about flavonoids from soy beans, grape seeds, tree barks, onion.....I remember that I wrote lots of nice comments about flavonoids as antioxidants.  Frankly I was in a shock after I did some reading about down sides of soy products. http://www.westonaprice.org/soy/darkside.html

    Researchers at the US Toxicological Laboratory in Arkansas found that the thyroid-depressing substances are isoflavones, the estrogen-like compounds found plentifully in the soybean. Isoflavones, which have both hormonal and nonhormonal properties. One concern is that soy may adversely affect thyroid function and interfere with the absorption of synthetic thyroid hormone. So it is important for soy food consumers to make sure their intake of iodine is adequate.

    Further confirmation of soy's adverse effects on the mind comes from a recent study of Japanese Americans living in Hawaii. Professor Lon White found a significant statistical relationship between two or more servings of tofu per week and "accelerated brain aging." Those participants who consumed tofu in mid-life had lower cognitive function in late life and a greater incidence of Alzheimer's and dementia. What's more," said Dr. White, "those who ate a lot of tofu, by the time they were 75 or 80, looked five years older." 

    There are too much to write them all here. So please do some research on your own online to take some precaution.

    Take care. wish everyone a healthy long life

    J