According to Kaayla Daniel, PhD, CCN, nutritionist and author of The Whole Soy Story: The Dark Side of America's Favorite Health Food, soy is not a health food, nor a panacea - and it has never even been proven safe. Rather, our current love affair with all things soy is "a triumph of marketing over real science." Just as important is the overlooked fact that the soy products we are encouraged to consume in the U.S. are far different than the soy foods traditionally consumed in Asian diets, which centers on small-to-moderate amounts of NATURALLY FERMENTED miso, soy sauce, tofu and tempeh made from organic, non-gmo beans.
For those who, like us, eat naturally fermented soy foods in relative moderation, see this organic soy scorecard. Do be aware that tofu is low in methionine and other essential nutrients, and, like "protein powders", should never be used as the sole source of protein.
Among the many problems with today's ersatz soy food products, one of the most troublesome has to do with parent's who are feeding their infants soy formula and therefore according to Dr. Daniel "unwittingly giving them the hormonal equivalent of three to five birth control pills a day" which then potentially interferes with brain and reproductive system development. This is particularly disturbing in view of the fact that - while a number of health authorities, including the Swiss Federal Health Service and The British Dietetic Association, have advised parents and pediatricians against the use of soy formula, a full 25% of bottle-fed American infants are given soy formula.
Here is the short list of problems associated with "ersatz" (non-fermented) soy products:
High levels of phytic acid in soy reduce assimilation of calcium, magnesium, copper, iron and zinc. Phytic acid in soy is not neutralized by ordinary preparation methods such as soaking, sprouting and long, slow cooking. High phytate diets have caused growth problems in children.
Trypsin inhibitors in soy interfere with protein digestion and may cause pancreatic disorders. In test animals soy containing trypsin inhibitors caused stunted growth.
Soy phytoestrogens disrupt endocrine function and have the potential to cause infertility and to promote breast cancer in adult women.
Soy phytoestrogens are potent antithyroid agents that cause hypothyroidism and may cause thyroid cancer. In infants, consumption of soy formula has been linked to autoimmune thyroid disease.
Vitamin B12 analogs in soy are not absorbed and actually increase the body's requirement for B12.
Soy foods increase the body's requirement for vitamin D.
Fragile proteins are denatured during high temperature processing to make soy protein isolate and textured vegetable protein.
Processing of soy protein results in the formation of toxic lysinoalanine and highly carcinogenic nitrosamines.
Free glutamic acid or MSG, a potent neurotoxin, is formed during soy food processing and additional amounts are added to many soy foods.
Soy foods contain high levels of aluminum which is toxic to the nervous system and the kidneys.
For both sides of the soy story, see this http://www.soyinfo.com/ soy information website.
For an informative rebuttal to Dr. Mark Hyman, see this article from the Weston Price Foundation.