Soy’s a health food, right? Well, like so many other substances, that’s what the "experts" have told us. However, contained in the United States Food and Drug Administration’s Poisonous Plant Database, which contains references to the scientific literature describing studies of the toxic properties and effects of plants and plant parts, under “soybean” there are 310 records. (1) The deleterious effects soy has on our bodies are caused by several different substances; we’re going to go over just a few.
One of the materials contained in soybeans is goitrogens. These are naturally occurring and interfere with the function of the thyroid gland. Goitrogens get their name from the term “goiter,” which means enlargement of the thyroid gland. (2) Other foods that contain goitrogens include broccoli, cabbage, mustard, peanuts, turnips, brussels sprouts and others. However, unlike soy, the goitrogens in these foods are quickly neutralized by cooking or fermentation. Heat, pressure or alkaline solutions will neither deactivate nor remove goitrogens from soy. (3) They are virtually in all soy foods, with the highest concentration being in products that are unfermented like tofu and soy sauce.
Another nasty class of substance in soy that can inflict damage upon your body is called phytoestrogens. Isoflavones are examples of phytoestrogens, and are in many plants, with the highest concentration being in soybeans. Phytoestrogens, although not hormones, are very similar and can bind to estrogen receptor sites and have been shown to cause adverse effects. Several studies have demonstrated the ability of phytoestrogens to decrease testosterone. (4-6)
There is not one reliable, valid study to show the benefits of soy protein over milk or other animal derived proteins. On the contrary, the soy protein powders that many supplement companies are selling, because it’s cheap, are not only extremely high in all the anti-nutrients above, the quality is dismally low.
The Protein Efficiency Ratio (PER) and the Biological Value (BV) which evaluate protein quality give soy a rating of 70 and 74 respectively. Whey and egg score over 100 and beef is over 80. The soy industry has set up a protein rating called the Protein Digestibility Corrected Amino Acid Score (PDCAAS). The catch is, no protein can score above 100. And soy was set as the standard at, you guessed it, 100. This way soy can never be outdone. Little tidbits the researchers who are funded by the soy industry don’t reveal. In other rating systems soy always falls short because of such small amounts of the essential sulfur amino methionine and because of extreme processing methods to enable humans to digest it.
Because soybeans aren't digestible, they are treated with heat, oxidizing agents, alkalis, acids and solvents. The quality of soy protein, which is low to start with, is compromised because it is one of the most processed foods there is.
The following is a list of myths and truths about soy taken from westonaprice.org:
Myth: Asians consume large amounts of soy foods.
Fact: Average consumption of soy foods in Japan and China is about 10g (about two teaspoons) per day. Asians consume soy foods in small amounts as a condiment, and not as a replacement for animal foods.
Myth: Soy foods provide complete protein.
Fact: Like all legumes, soy beans are deficient in sulfur-containing amino acids methionine and cystine. Also, modern processing denatures fragile lysine.
Myth: Fermented soy foods can provide vitamin B12 in vegetarian diets.
Fact: The compound in soy that resembles vitamin B12, cannot be used by the human body; in fact, soy foods cause the body to require more B12.
Myth: Soy formula is safe for infants.
Fact: Soy foods contain trypsin inhibitors that inhibit protein digestion and affect pancreatic function. In test animals, diets high in trypsin inhibitors led to stunted growth and pancreatic disorders. Soy foods increase the body’s requirement for vitamin D, needed for strong bones and healthy growth. Phytic acid in soy foods results in reduced bioavailability of iron and zinc which are required for the health and development of the brain and nervous system. Soy also lacks cholesterol, likewise essential for the development of the brain and nervous system. Megadoses of phytoestrogens in soy formula have been implicated in the current trend toward increasingly premature sexual development in girls and delayed or retarded sexual development in boys.
Myth: Soy estrogens (isoflavones) are good for you.
Fact: Soy isoflavones are phyto-endocrine disrupters. At dietary levels, they can prevent ovulation and stimulate the growth of cancer cells. Eating as little as 30 grams (about four tablespoons) of soy per day can result in hypothyroidism with symptoms of lethargy, constipation, weight gain and fatigue.
Myth: Soy isoflavones and soy protein isolate, found in all soy protein powders, have Generally Recognized as Safe (GRAS) status.
Truth: Archer Daniels Midland (ADM) recently withdrew its application to the FDA for GRAS status for soy isoflavones following an outpouring of protest from the scientific community.The FDA never approved GRAS status for soy protein isolate because of concern regarding the presence of toxins and carcinogens in processed soy.
Myth: Soy foods are good for your sex life.
Truth: Isoflavones in soy have been shown in several studies to lower total testosterone and increase sex hormone binding globulin which adheres itself to free testosterone rendering it inactive. Numerous animal studies show that soy foods cause infertility in animals. Japanese housewives feed tofu to their husbands frequently when they want to reduce his virility.