These soy products greatly inhibit zinc and iron absorption; in test animals they cause enlarged organs, particularly the pancreas and thyroid gland, and increased deposition of fatty acids in the liver. Human feeding tests to determine the cholesterol lowering properties of soy protein isolate have not shown them to be effective. Nevertheless, they are often promoted as having beneficial effects on cholesterol levels.
Cancer Preventing or Cancer Causing? The food industry also touts soy products for their cancer preventing properties. Isoflavone aglycones are anticarcinogenic substances found in traditionally fermented soybean products. However, in non-fermented soy products such as tofu and soy milk, these isoflavones are present in an altered form as beta-glycoside conjugates, which have no anti-carcinogenic effect. Some researchers believe the rapid increase in liver and pancreatic cancer in Africa is due to the introduction of soy products there.
The fatty acid profile of the soybean includes large amounts of beneficial omega-3 fatty acids compared to other pulses legumes); but these omega-3 fatty acids are particularly susceptible to rancidity when subjected to high pressures and temperatures. This is exactly what is required to remove oil from the bean, as soybean oil is particularly difficult to extract. hexane or other solvents are always used to extract oil from soybeans, and traces remain in the commercial product.