soymyths

Myth: Use of soy as a food dates back many thousands of years.

Truth: Soy was first used as a food during the late Chou dynasty (1134-246 BC), only after the Chinese learned to ferment soy beans to make foods like tempeh, natto and tamari.



Myth: Asians consume large amounts of soy foods.

Truth: Average consumption of soy foods in Japan and China is 10 grams (about 2 teaspoons) per day. Asians consume soy foods in small amounts as a condiment, and not as a replacement for animal foods.



Myth: Modern soy foods confer the same health benefits as traditionally fermented soy foods.

Truth: Most modern soy foods are not fermented to neutralize toxins in soybeans, and are processed in a way that denatures proteins and increases levels of carcinogens.



Myth: Soy foods provide complete protein.

Truth: Like all legumes, soy beans are deficient in sulfur-containing amino acids methionine and cystine. In addition, modern processing denatures fragile lysine.



Myth: Fermented soy foods can provide vitamin B12 in vegetarian diets.

Truth: The compound that resembles vitamin B12 in soy 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.

Truth: 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 normal growth. Phytic acid in soy foods results in reduced bioavailabilty 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 foods can prevent osteoporosis.

Truth: Soy foods can cause deficiencies in calcium and vitamin D, both needed for healthy bones. Calcium from bone broths and vitamin D from seafood, lard and organ meats prevent osteoporosis in Asian countries—not soy foods.



Myth: Modern soy foods protect against many types of cancer.

Truth: A British government report concluded that there is little evidence that soy foods protect against breast cancer or any other forms of cancer. In fact, soy foods may result in an increased risk of cancer.



Myth: Soy foods protect against heart disease.

Truth: In some people, consumption of soy foods will lower cholesterol, but there is no evidence that lowering cholesterol improves one’s risk of having heart disease.



Myth: Soy estrogens (isoflavones) are good for you.

Truth: 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 4 tablespoons) of soy per day can result in hypothyroidism with symptoms of lethargy, constipation, weight gain and fatigue.



Myth: Soy foods are safe and beneficial for women to use in their postmenopausal years.

Truth: Soy foods can stimulate the growth of estrogen-dependent tumors and cause thyroid problems. Low thyroid function is associated with difficulties in menopause.



Myth: Phytoestrogens in soy foods can enhance mental ability.

Truth: A recent study found that women with the highest levels of estrogen in their blood had the lowest levels of cognitive function; In Japanese Americans tofu consumption in mid-life is associated with the occurrence of Alzheimer’s disease in later life.



Myth: Soy isoflavones and soy protein isolate have GRAS (Generally Recognized as Safe) 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: Numerous animal studies show that soy foods cause infertility in animals. Soy consumption enhances hair growth in middle-aged men, indicating lowered testosterone levels. Japanese housewives feed tofu to their husbands frequently when they want to reduce his virility.



Myth: Soy beans are good for the environment

Truth: Most soy beans grown in the US are genetically engineered to allow farmers to use large amounts of herbicides.



Myth: Soy beans are good for the environment.

Truth: Most soy beans grown in the US are genetically engineered to allow farmers to use large amounts of herbicides.



Myth: Soy beans are good for developing nations.

Truth: In third world countries, soybeans replace traditional crops and transfer the value-added of processing from the local population to multinational corporations.
http://www.soyonlineservice.co.nz/03soymyths.htm
 

Other studies raise concerns about soy's effect on hormones, for example: One study found that children with autoimmune thyroid disease are more likely to have been fed soy-based infant formula.

A 1991 Japanese study found that soy consumption can suppress thyroid function and cause goiters in healthy people, especially elderly subjects.

Czech researchers in 2006 reported on a study that looked at thyroid hormones and thyroid autoantibodies, along with blood levels of two isoflavones -- daidzein and genistein. The study looked at children without overt thyroid disease, who were not iodine deficient. They found a "significant positive association of genistein with thyroglobulin autoantibodies and a negative correlation with thyroid volume." They concluded that "even small differences in soy phytoestrogen intake may influence thyroid function, which could be important when iodine intake is insufficient."

In 2004, researchers found that infants fed soy formula had a prolonged increase in their thyroid stimulating hormone (TSH) levels, compared to infants fed non-soy formula.

European researchers found in one study that even a week of consuming unprocessed boiled natural soybeans caused modest changes to thyroid levels.

A 1997 study published in the journal Biochemical Pharmacology wrote: "it was observed that an...extract of soybeans contains compounds that inhibit thyroid peroxidase- (TPO) catalyzed reactions essential to thyroid hormone synthesis

 

http://thyroid.about.com/cs/soyinfo/a/soy_2.htm