There is lots of controversy about whether soy is good for breast cancer risk.

Q: There is lots of controversy about whether soy is good for breast cancer risk. What supports the thought you have that type A people should eat lots of tofu?

A: There is tremendous debate that occurs around the benefits of soy for breast cancer. Five years ago, studies were showing soy is good. Now, it is the other way around. There are researches pointing to the use of tofu (10% dry weight contains lectin), which binds to cancer cells especially for type A people. I think this whole arena of research is unclear at best. The reason is simple: We are still at the infancy stage of understanding what nutrient can do and at what dosage. So it is common to have opposing studies since each study tries to isolate the nutrient and come to a cause-effect relationship, which is not possible. You have to understand that nutrients do not behave like drugs. The curve is not linear, and the results often are paradoxical, depending on dosage. For example, 100 mg of Vitamin C is an anti- oxidant, while 10,000 of vitamin C acts as an oxidant. It is, therefore, common to be confused unless you are into the research.
I would suggest that until the science is more definitive, which will take another 10 years, you err on the side of moderation. Fermented soy such as miso, tempeh, and natto are very good. Unfermented soy, such as tofu, should be taken in moderation at best.
The Blood Type Diet is based on how the protein in the food (called leptin) affects blood agglutination. The diet is founded by Dr. Peter D’adamo. There are some principles in the Blood Type Diet that are not accepted in conventional medicine and their recommendations. Water and soy are a few of these discrepancies.