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Daniel
The whole soy story: the dark side of America's favorite health food.Daniel KT Book. New Trends Publishing, Inc, 2005
"Soy foods always enter the body carrying their cargo of other anti-nutritional factors--saponins, soyatoxin, phytates, protease inhibitors, oxalates, goitrogens and estrogens, all of which have shown the potential to cause harm." (p 236)
"Although the best known goitrogens in soy are the isoflavones, the Japanese researcher Shuichi Kimura discovered back in the mid-1970s that saponins can also spur enlargement of the thyroid." (p 240)
"Soybeans contain goitrogens. Goitrogens are substances that block the synthesis of thyroid hormones. As their name suggest, they can cause goiter, which is a pronounced swelling in the neck caused by an enlarged thyroid gland." (p 311)
"Soy is not the only goitrogenic food. Broccoli, cabbage, Brussels sprouts, cassava, rapeseed, turnips, mustard, radish, peanuts and millet also contain goitrogens. However, few adults--and even fewer children--eat these foods to excess. Furthermore, the goitrogens in most of these foods are easily neutralized by cooking or fermentation.
"Soy foods are different. The principal goitrogens in soybeans are the estrogenic plant hormones known as isoflavones. The antinutrients known as saponins in soy may also be goitrogens.... Cooking and processing methods using heat, pressure and alkaline solutions will neither deactivate nor remove isoflavones or saponins. Only solvent extraction can do that. So far, the soy industry has resisted using these processes--even for soy destined for babies, who are highly vulnerable to their estrogenic and goitrogenic effects." (pp 311-2)
"The causes of so much thyroid disease appear to be many and synergistic. Radiation, mercury, fluoride, plastics, pesticides, dioxins, solvents and estrogens (and estrogen mimickers) found in commercial meats, plastics and hormone replacement therapies (HRT) have all been implicated. And so has soy.
"The United Kingdom's Committee on Toxicity (COT) has identified several populations at special risk for soy-induced thyroid disease--infants on soy formula, vegans who use soy as their principal meat and dairy replacements, and men and women who are self medicating with soy foods and/or isoflavone supplements in an attempt to prevent or reverse menopausal symptoms, cancer or high cholesterol. As early as 1980, British government researchers pointed out that soy-consuming vegans were at risk." (pp 313-4)
"Although iodine deficiency increases the antithyroid effects of goitrogenic foods, iodine sufficiency does not offer complete protection in the face of high soy consumption." (p 315)
"The first report in medical journals of enlarged thyroid glands in rats and chickens fed soybean rations appeared in the 1930s. In 1961, researchers discovered that spiking the chow with iodine could prevent goiter. But this quick-fix solution to a serious problem turned out to be simplistic. Rats and chickens fed soybean-based chows required twice as much iodine to prevent thyroid enlargement as animals fed soy free diets. Even then, their thyroid glands showed abnormal cell proliferation. When iodine is largely absent, soy can provoke malignant hyperplastic goiter.
"Dr. Mieko Kimura of Kyoto University writes: "It is well known that a goiter is induced by simple iodine deficiency, but it was noteworthy that hyperplastic goiters can be induced in rats in a high percentage by the administration of soybean factor(s) under iodine-deficient conditions, together with accurate signs of malignancy such as invasiveness and metastasis formation in the lungs." (p 315)
"Likewise, the soy estrogens known as the isoflavones can inhibit the action of thyroid drugs. to ensure their efficacy, many health professionals recommend that they not be taken at the same time as food or supplements high in soy." (p 316)
"Boosting the thyroid with drugs like Synthroid, then depressing it with thyroid inhibitors like soy foods or isoflavone supplements can put extreme stress on the thyroid. Environmental scientist Mike Fitzpatrick, Ph.D., points out that this is the classic way that researchers induce thyroid tumors in laboratory animals. The fact that soy is "natural" does not make it safe or weak. A serving of soy food provides up to three times the goitrogenic potency of the pharmaceutical thyroid-inhibiting drugs methimazole and 6-propylthiouracil." (p 316)
"Mechanisms of action. Plant estrogens interact with the thyroid gland in several ways. Genistein and daidzein (the key isoflavones in soy) and biochanin A (found in clover and alfalfa) are potent inhibitors of thyroid peroxidase (TPO), an enzyme involved in the synthesis of T3 and T4. In vitro experiments have shown that soy isoflavone's inhibition of thyroid peroxidase interferes with a critical stage in thyroid hormone production--the iodinization of the amino acid tyrosine.
"This interference occurs whether or not sufficient or extra iodine is present. As a result, the body produces useless mono-, di- and tri-iodoisoflavones and not the mono, di, and tri and quarto forms of thyroid hormone. In the human body, this interference can cause a drop in thyroid hormone levels, an increase in thyroid stimulating hormone and stress on the thyroid gland." (p 317)
"Another way goitrogens damage thyroid function is by increasing concentrations of thyroid binding globulin (TBG), a plasma protein involved in the inactivation and transport of T3 and T4. This lowers free thyroxine concentrations and increases TSH secretions." (pp 317-8)
"The first reports of thyroid damage suffered by human infants on soy formula appeared during the 1950s. Most cases involved goiter, with no overt signs of hypothyroidism. Although iodine supplements helped, they did not entirely solve the problem. Researchers found that matters improved considerably if the processing of the soy formula included extraction with an organic solvent as well as heating. Although no one at the time identified the principal goitrogens as the isoflavones, alcohol solvent extraction is, in fact, the only way to remove them. Heat, pressure and alkaline treatments used in ordinary soy processing will not remove the isoflavones." (p 318)
"Autoimmune thyroid disease is far more likely to occur in children who were fed soy formula." (p 318)
"The most powerful evidence of soy's adverse effects on the adult thyroid emerged from a study carried out at the Ishizuki Thyroid Clinic in Japan. Dr. Yoshimochi Ishizuki of Aichi Medical University demonstrated that 30 grams of pickled soybeans per day, given to healthy adult men and women, induced thyroid disruptions in only 30 days. All subjects consumed seaweed daily to ensure adequate iodine intake." (p 320)
"Soy eaters are at risk for thyroid damage not only because of the goitrogens in soy but also because phytates contribute to zinc deficiency and an "anti-vitamin factor" results in greater needs of the body for vitamin B-12." (pp 322-3)
"Soybeans naturally contain goitrogens, allergens, protease inhibitors and other antinutrients and toxins that damage the digestive, immune and neuroendocrine systems, putting consumers at increased risk for many health problems, including cancer." (p 381)
The Whole Soy Story -- Website
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