My husband and I have an extensive garden. I suggested one day that he grow soybeans because they are so tasty as edamame. He told me that unprocessed soybeans are toxic. Skeptical to the end, I decided to go online, where the answer would be at my fingertips. I was shocked. There are actually several substances in unprocessed soybeans that are very unhealthy for you including phytoestrogens, antienzymes, hemagglutinin, phytates and goitrogens and a breakdown of the effect that each of these substances has on the body will follow. Fermentation reduces or eliminates many of these toxic chemicals. Fermented soy products include tempeh and miso; however, processed unfermented soy products still contain many of the harmful ingredients that raw soybeans have. In addition, hexane is one method for separating out the oil from the bean and is a known carcinogen. Most of the hexane is removed through distillation, however, some residue remains and manufacturers are not obligated to provide hexane amounts in their list of ingredients. Aluminum is high in soy baby formula because the process of making soy protein isolate involves giving the soy beans and acid wash in aluminum tanks resulting in some soy based formulas having up to 100 times more aluminum than in cow’s milk.
Phytoestrogens and Goitrogens are present in raw soybeans in the form of isoflavones. There is some controversy over the effect that these non nutrients have. Some sources say that these estrogen mimicking plant products can reduce male fertility if eaten in large quantities; especially during childhood. In the July 24/08 edition of Human Reproduction, a leading health journal in Europe, there is an article that has studied the effect of eating an average of half a serving per day of soybean products and found that consumption lead to a significant decrease in sperm count. Other sources indicate that this effect is minimal to non existent and in addition, the small amount of plant estrogen can reduce the incidence of prostate cancer. These same phytoestrogens found in soy beans also depress thyroid function and may cause goiter if consumed regularly over a long period of time. Even processing doesn’t denature phytoestrogens.
Antienzymes, specifically, a tripsin antagonist is one of the most troublesome elements in the raw soybean. Tripsin is required by the small intestine to digest protein. Without it, the pancreas have to work overtime to allow protein to move through the digestion process. Raw soy flour is known to cause pancreatic cancer in rats. Tripsin also interferes with the uptake of the protein that naturally occurs in the soybean, defeating its own purpose in vegan diets. There really isn’t any controversy over this component of the soybean, except to say that high heat and fermentation take care of a lot of the tripsin antagonist, but not all. In addition soy milk and baby formula still contain significant amounts of tripsin antagonist and manufacturers do not have to disclose the antitripsin concentration on their ingredient labels.
Hemagglutinin or phytohemagglutinin is found in soybeans and many other beans including red and white kidney beans, fava beans and in some green beans. This substance binds red blood cells (and some white blood cells) into clumps that can turn into blood clots. Tofu contains reduced amounts – it isn’t fermented, while fermentation denatures hemagglutinins.
Soybeans are very high in phytates, chemicals that prevent the uptake of calcium, magnesium, iron and zinc by the body. If the diet isn’t adequately supplemented with foods high in these substances, a diet high in soy could put you at risk for severe mineral deficiency. Fermented products contain less phytates, but tofu has the same amount as in the unprocessed bean. In addition, soy milk has high amounts of phytates. The process of making soy milk, while we are on the subject, removes the amino acids lysine and cystine and denatures the proteins that naturally occur, making any protein remaining in the soy milk to be virtually undigestible.
Lastly, a note should be made about pesticides and herbicides. Soy beans are a huge cash crop in the United States; most hydrogenated vegetable oils use soy bean oil as their base. These pesticides and herbicides remain in soy products after processing. If I were feeding my family, I would go with organic tofu. As with all food products, read your ingredient labels and consume in moderation.