The Dangers of Soy to Human Health

Excerpt from
The Holistic Health Doctor’s Family Guide to Natural Wellness © 2010
By Dr. Nancy Taylor

Most people do not realize that soy is no longer considered a health food. “Over the past decade or so, soy has been touted by the media and certain dietary organizations as a health food. This is nothing more than a multi-million dollar marketing strategy. In fact, the soy industry is one of the world’s most wealthy and powerful multi-billion dollar industries…” (Soy On Line Services)

Commercial Soy Fields: A Multi-Million Dollar Agribusiness

Soy contains a number of chemical toxins and currently there is no effort to remove these potent toxins. It contains high levels of phytic acid, trypsin inhibitors, toxic lysinoalanine and highly carcinogenic nitrosamines. “(There is) an impressive array of scientific evidence that soy is not a fit food for man … the widespread use of non-fermented soy is part of the chronic disease problem since soy is known to wreak havoc with the human thyroid and other hormone systems.” True Health, the magazine of Carotec Inc., Naples, Florida. May/June 2004.

Phytoestrogens which act like estrogen in the body, are found in soy and disrupt endocrine function. They are toxic to healthy thyroid functioning. Infants fed soy-based formula have 13,000 to 22,000 times more estrogen compounds in their blood than babies fed milk-based formula, which is the equivalent of five birth control pills a day. Infant soy formula has also been linked to auto immune thyroid disease.

In 2007 the Food and Drug Administration (FDA) announced an opportunity for public comment: “…on its intent to reevaluate the scientific evidence for two previously authorized health claims (dietary lipids (fat) and cancer; soy protein and risk of coronary heart disease) and two qualified health claims that were the subject of letters of enforcement discretion (antioxidant vitamins and risk of certain cancers; selenium and certain cancers). The agency is undertaking a reevaluation of the scientific basis for these authorized health claims and qualified health claims because of new scientific evidence that has emerged for these substance-disease relationships. The new scientific evidence may have the effect of weakening the substance-disease relationship for these authorized health claims and either strengthening or weakening the scientific support for the substance-disease relationship for these qualified health claims.” The Federal Register, December 21, 2007.

Soy is linked to infertility, breast cancer, hypothyroidism and thyroid cancer as well as many other health problems. The premature sexual development of girls has been linked to the use of soy formula, as well as the underdevelopment of males.

From the Report of the New Zealand House of Representatives Health Committee:
“We accept that there is evidence that soy-based formulas have a high phytoestrogen content that may pose a risk to the long-term reproductive health of infants…”(

Soy is Added to Our Food Supply
Soy can be found in many ingredients including dog food. It may be added as a filler or allowed to be used to meet an FDA nutrient labeling requirement. “Imagine drugs that are known, by years of scientific documentation, to be both carcinogenic and to also cause DNA and chromosome damage being prescribed and administered through the food supply to populations of many countries around the world without the knowledge or consent of the individuals consuming these foods … with no way to track dosage, individual reactions, or harmful side-effects … and without any concern for some people’s increased vulnerability to these drugs, such as cancer patients. It sounds crazy, but that is exactly what is happening around the world when Soy is added to our food supply. Soy contains the scientifically documented carcinogenic and DNA damaging and chromosome damaging natural chemicals genistein and daidzein.” True Health, the magazine of Carotec Inc., Naples, Florida. May/June 2004.

“(Soyfoods) are not nutrients. They are drugs.”
Dr. L. White, Honolulu Aging Study.

“…even the American Heart Association confirms that neither the safety nor efficacy of soy isoflavone supplements have been proven…(and) recently reversed their position regarding the health benefits of soy, now stating that the food has little effect on cholesterol and is unlikely to prevent heart disease.”

The Corporate Golden Nugget

Myths about Soy from Soy on Line Services
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.

References on the Dangers of Soy
1. Atanassova N et al. Comparative Effects of Neonatal Exposure of Male Rats to Potent and Weak (Environmental) Estrogens on Spermatogenesis at Puberty and the Relationship to Adult Testis Size and Fertility: Evidence for Stimulatory Effects of Low Estrogen Levels. Endocrinology. 2000 Vol. 141, No. 10.
2. Chorazy PA et al. Persistent hypothyroidism in an infant receiving a soy formula: case report and review of the literature. Pediatrics. 1995 Jul: 96 (1 Pt 1): 148-50.
3. Irvine CHG et al. Phytoestrogens in soy-based infant foods: concentrations, daily intake, and possible biological effects. Proc Soc Exp Biol Med. 1998 Mar; 217 (3): 247-53.
4. Lohrke B et al. Activation of skeletal muscle protein breakdown following consumption of soybean protein in pigs. Br J Nutr. 2001 Apr; 85 (4): 447-57.
5. Nagata C et al. Inverse association of soy product intake with serum androgen and estrogen concentrations in Japanese men. Nutr Cancer. 2000; 36 (1): 14-8.
6. Newbold RR et al. Uterine Adenocarcinoma in Mice Treated Neonatally with Genistein. Cancer Research. 2001; 61, 4325-4328.
7. Pollard M et al. Prevention of spontaneous prostate-related cancer in Lobund-Wistar rats by soy protein isolate/isoflavone diet. Prostate. 2000 Oct 1; 45 (2): 101-5.
8. Strauss L et al. Genistein exerts estrogen-like effects in male mouse reproductive tract. Mol Cell Endocrinol. 1998 Sep 25; 144 (1-2): 83-93.
9. Weber KS et al. Dietary soy-phytoestrogens decrease testosterone levels and prostate weight without altering LH, prostate 5alpha-reductase or testicular steroidogenic acute regulatory peptide levels in adult male Sprague-Dawley rats. J Endocrinol. 2001 Sep; 170 (3): 591-9.
10. Strauss et al. Genistein exerts estrogen-like effects in male mouse reproductive tract, Mol Cell Endocrinol. 1998 Sep 25;144(1-2);83-93.
11. Casanova M et al. Developmental effects of dietary phytoestrogens in Sprague-Dawley rats and interactions of genistein and diadzein with rat estrogen receptors alpha and beta in vitro. Toxicol Sci. 1999 Oct;51(2):236-44
12. Kumi-Diaka J et al. Cytotoxic potential of the phytochemical genistein isoflavone and certain environmental chemical compounds on testicular cells. Biol Cell. 1999 Sep;91 (7): 515-23.
13. Anderson et al. Effect of various genotoxins and reproductive toxins in human lymphocytes and sperm in Comet assay. Teratog Carcinog Mutagen. 1997;17(1);29-43.
14. Zhong et al. Effects of dietary supplement of soy protein isolate and low fat diet on prostate cancer. FASEB J 2000;14(4):a531.11.
15. Nagata C et al. Inverse association of soy product intake with serum androgen and estrogen concentrations in Japanese men. Nutr Cancer 2000;36(1):14-8.
16. Habito RC et al. Effects of replacing meat with soyabean in the diet on sex hormone concentrations in healthy adult males. Br J Nutr 2000 Oct;84(4):557-63.
17. Klein M et al. Energy metabolism and thyroid hormone levels of growing rats in response to different dietary proteins – soy or casein. Arch Tierernahr 2000;53(2):99-125.
18. Flynn KM et al. Effects of genistein exposure on sexually dimorphic behaviors in rats. Toxicol Sci 2000 Jun;55(2):311-9.
19. Atanassova N et al. Comparative effects of neonatal exposure of male rats to potent and weak (environmental) estrogens on spermatogenesis at puberty and the relationship to adult testis size and fertility: evidence for stimulatory effects of low estrogen levels. Endocrinology 2000 Oct;141(10):3898-907.
20. Whitten PL et al. Phytoestrogen influences on the development of behavior and gonadotropin function. Proc Soc Exp Biol Med 1995 Jan;208(1):82-6
21. Kumi-Diaka J, et al. Cytotoxic potential of the phytochemical genistein isoflavone (4′,5′,7-trihydroxyisoflavone) and certain environmental chemical compounds on testicular cells. Biol Cell 1999 Sep;91(7):515-23
22. Ashton E, Ball M. Effects of soy as tofu vs meat on lipoprotein concentrations. Eur J Clin Nutr 2000 Jan;54(1):14-9
23. Madani S, et al. Dietary protein level and origin (casein and highly purified soybean protein) affect hepatic storage, plasma lipid transport, and antioxidative defense status in the rat. Nutrition 2000 May;16(5):368-75.
24. Cline JM. Effects of dietary isoflavone aglycones on the reproductive tract of male and female mice. Toxicol Pathol. 2004 Jan-Feb;32(1):91-9.
25. Dillingham BL et al. Soy protein isolates of varying isoflavone content exert minor effects on serum reproductive hormones in healthy young men. J Nutr. 2005 Mar;135(3):584-91.
26. Sacks FM et al: American Heart Association Nutrition Committee. Soy protein, isoflavones, and cardiovascular health: an American Heart Association Science Advisory for professionals from the Nutrition Committee. Circulation. 2006 Feb 21;113(7):1034-44. Epub 2006 Jan 17.
27. Sirtori CR et al. Phytoestrogens: end of a tale? Ann Med. 2005;37(6):423-38.

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7 Responses to The Dangers of Soy to Human Health

  1. Linda Kendall-Hagan says:

    Wow! Dr. Nancy, you really smashed all the soy myths. Thanks! No wonder I got sick and anemic years ago when I tried to be a vegetarian by surviving on soybeans and veggies alone.

    • Thanks Linda. Vegetarians sometimes have difficulty with this, especially when they have used soy for many years. Soy is not meant for humans. We just don’t have the biochemistry to digest it and eliminate the toxins properly.

  2. Carla J Gardiner says:

    Wow, this really hits home. I tired soy milk as a replacement for cows milk and my system didn’t like it at all, very painful diahrea and cramping. I stopped using both milk and soy milk and use cows milk sparingly for cooking only.

    Everyone should sit up and take notice, this really explains a lot of chronic illness issues that could be prevented. Thanks for taking the time to share with all of us.

    • Using soy has long range detrimental effects. Buyer beware! I met a man with Hodgkins Lymphoma (cancer in the lymph system). Everything he ate was soy: soy ice cream, soy protein in chili, bacon replacement, etc. He REFUSED to read this and the articles found on the Weston Price Foundation website. I hope he changed his position. I have not heard from he or his wife for about 4 years now.

  3. Catherine says:

    What do we do??? As much as I try to go Healthy ie:
    Vegan diet
    Starbucks Soy Lattes
    Now I don’t know what to eat.
    Dairy or no dairy
    Calcuim through greens
    Do I drink Coconut, almond, hemp or rice milk.
    Soy seemed like such an easy segwae to the vegan lifestyle.

  4. Vern says:

    Whoa….such a important online site.

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