Tragedy and Hype: The Third International Soy Symposium – Part II

by Sally Fallon and Mary G. Enig, PhD

All Rights Reserved. ©2000

Phytoestrogens – Panacea or Poison?

The male species of tropical birds carries the drab plumage of the female at birth and “colors up” at maturity, somewhere between nine and 24 months. In 1991, Richard and Valerie James, bird breeders in Whangerai, New Zealand, purchased a new kind of feed for their birds, one based largely on soy protein.47 When soy-based feed was used, their birds “colored up” after just a few months. In fact, one bird food manufacturer claimed that this early development was an advantage imparted by the feed. A 1992 ad for Roudybush feed formula showed a picture of the male crimson rosella, an Australian parrot that acquires beautiful red plummage at 18 to 24 months, already brightly colored at 11 weeks old.

Unfortunately, in the ensuing years, there was decreased fertility in the birds with precocious maturation, deformed, stunted and still-born babies, and premature deaths, especially among females, with the result that the total population in the avaries went into steady decline. The birds suffered beak and bone deformities, goitre, immune system disorders and pathological aggressive behavior. Autopsy revealed digestive organs in a state of disintegration. The list of problems corresponded with many of the problems the Jameses had encountered in their two children, who had been fed soy-based infant formula.

Startled, aghast, angry…the Jameses hired toxicologist Mike Fitzpatrick to investigate further. Dr. Fitzpatrick’s literature review uncovered evidence that soy consumption has been linked to numerous disorders, including infertility, increased cancer and infantile leukemia; and, in studies dating back to the 1950s,48 that genistein in soy causes endocrine disruption in animals. Dr. Fitzpatrick also analyzed the bird feed and found that it contained high levels of phytoestrogens, especially genistein. When the Jameses discontinued using soy-based feed, the flock gradually returned to normal breeding habits and behavior.

The Jameses embarked on a private crusade to warn the public and government officials about soy foods, particularly the endocrine disrupting isoflavones (genistein and diadzen.) Protein Technologies International (PTI) received their material in 1994.

In 1991, Japanese researchers reported that consumption of as little as 30 grams or 2 tablespoons of soybeans per day for only one month resulted in a significant increase in thyroid stimulating hormone.49 Diffuse goitre and hypothyroidism appeared in some of the subjects and many complained of constipation, fatigue and lethargy, even though their intake of iodine was adequate. In 1997, researchers from the FDA’s National Center for Toxicological Research made the embarrassing discovery that the goitrogenic components of soy were the very same isoflavones.50

Twenty-five grams of soy protein isolate, the minimum amount PTI claimed to have cholesterol-lowering effects, contains at least 50 mg of isoflavones. It took only 45 mg daily of isoflavones in premenopausal women to exert significant biological effects including reduction in hormones needed for adequate thyroid function. These effects lingered for three months after soy consumption was discontinued.51

One hundred grams of soy protein, the maximum suggested cholesterol-lowering dose (and the amount recommended by Protein Technologies International), can contain almost 600 mg of isoflavones,52 an amount that is undeniably toxic. In 1992, the Swiss health service estimated that 100 grams of soy protein provided the estrogenic equivalent of the pill.53

In vitro studies suggest that isoflavones inhibit synthesis of estradiol and other steroid hormones.54 Reproductive problems, infertility, thyroid disease and liver disease due to dietary intake of isoflavones have been observed for several species of animals including mice, cheetah, quail, pigs, rats, sturgeon and sheep.55

It is the isoflavones in soy that are said to have a favorable effect on postmenopausal symptoms, including hot flashes and protection from osteoporosis. Quantification of discomfort from hot flashes is extremely subjective and most studies show that control subjects report reduction in discomfort in amounts equal to subjects given soy.56

The claim that soy prevents osteoporosis is extraordinary, given that soy foods block calcium and cause vitamin D deficiencies. If Asians indeed have lower rates of osteoporosis than Westerners, it is because their diet provides plenty of vitamin D from shrimp, lard and sea food; and plenty of calcium from bone broths. The reason that Westerners have such high rates of osteoporosis is because they have substituted soy oil for butter, which is a traditional source of vitamin D and other fat-soluble activators needed for calcium absorption.

Birth Control Pills for Babies

But it was the isoflavones in infant formula that gave the James family the most cause for concern. In 1998, investigators reported that the daily exposure of infants to isoflavones in soy infant formula is six to eleven times higher on a body weight basis than the dose that has hormonal effects in adults consuming soy foods. Circulating concentrations of isoflavones in infants fed soy-based formula were 13,000 to 22,000 times higher than plasma estradiol concentrations in infants on cows’ milk formula.57

Approximately 25% of bottle-fed children in the US receive soy-based formula – a much higher percentage than in other parts of the Western world. Fitzpatrick estimated that an infant exclusively fed soy formula receives the estrogenic equivalent (based on body weight) of at least five birth control pills per day.58 By contrast, almost no phytoestrogens have been detected in dairy-based infant formula or in human milk, even when the mother consumes soy products.

Scientists have known for years that soy-based formula can cause thyroid problems in babies. But what are the effects of soy products on the hormonal development of the infant, both male and female? Male infants undergo a “testosterone surge” during the first few months of life, when testosterone levels may be as high as those of an adult male. During this period, the infant is programmed to express male characteristics after puberty, not only in the development of his sexual organs and other masculine physical traits, but also in setting patterns in the brain characteristic of male behavior. In monkeys, deficiency of male hormones impairs the development of spatial perception (which, in humans, is normally more acute in men than in women), of learning ability and of visual discrimination tasks (such as would be required for reading.)59 It goes without saying that future patterns of sexual orientation may also be influenced by the early hormonal environment. Male children exposed during gestation to diethylstilbesterol (DES), a synthetic estrogen that has effects on animals similar to those of phytoestrogens from soy, had testes smaller than normal on maturation.60

Learning disabilities and behavioral problems, especially in male children, have reached epidemic proportions. Soy infant feeding — which began in earnest in the early 1970s — cannot be ignored as a probable cause for these tragic developments.

As for girls, an alarming number are entering puberty much earlier than normal, according to a recent study reported in the journal Pediatrics.61 Investigators found that one percent of all girls now show signs of puberty, such as breast development or pubic hair, before the age of three; by age eight, 14.7% of white girls and almost 50% of African-American girls had one or both of these characteristics. New data indicate that environmental estrogens such as PCBs and DDE (a breakdown product of DDT) may cause early sexual development in girls.62 In the 1986 Puerto Rico Premature Thelarche study, the most significant dietary association with premature sexual development was not chicken — as reported in the press — but soy infant formula.63 The Woman, Infants and Children (WIC) program, which supplies free infant formula to welfare mothers, stresses soy formula for African Americans because they are supposedly allergic to milk.

The consequences of truncated childhood are tragic. Young girls with mature bodies must cope with feelings and urges that most children are not well-equipped to handle. And early maturation in girls is frequently a harbinger for problems with the reproductive system later in life – including failure to menstruate, infertility and breast cancer. Parents who have contacted the Jameses recount other problems associated with children of both sexes who were fed soy-based formula, including extreme emotional behavior, asthma, immune system problems, pituitary insufficiency, thyroid disorders and irritable bowel syndrome — the same endocrine and digestive havoc that afflicted the James’ parrots.

Dissention in the Ranks

Organizers of the Third International Soy Symposium would be hard pressed to call the conference an unqualified success. On the second day of the conference the London-based Food Commission and the Weston A Price Foundation of Washington, DC held a joint press conference in the same hotel to present concerns about soy infant formula. Industry representatives sat stony faced through the recitation of potential dangers and a plea from concerned scientists and parents to pull soy-based infant formula from the market. Under pressure from the Jameses, the New Zealand government had issued a health warning about soy infant formula in 1998. It was time for the American government to do the same.

On the last day of the conference, presentations on new findings related to toxicity sent a well-oxygenated chill through the industry’s giddy helium hype. Dr. Lon White reported on a study of Japanese Americans living in Hawaii. It showed a significant statistical relationship between two or more servings of tofu per week and “accelerated brain aging.”64 Those participants who consumed tofu in midlife had lower cognitive function in late life and a greater incidence of Alzheimers and dementia. “What’s more,” said Dr. White, “those who ate a lot of tofu, by the time they were 75 or 80, looked five years older.”65 White and his colleagues blamed the negative effects on isoflavones, a finding that supports an earlier study in which post-menopausal women with higher levels of circulating estrogen experienced greater cognitive decline.66

Scientists Daniel Sheehan and Daniel Doerge from the National Center for Toxicological Research ruined PTI’s day by presenting findings from rat feeding studies indicating that genistein in soy foods causes irreversible damage to enzymes that synthesize thyroid hormones.67 “The association between soybean consumption and goiter in animals and humans has a long history,” wrote Dr. Doerge. “Current evidence for the beneficial effects of soy requires a full understanding of potential adverse effects as well.” Dr. Claude Hughes reported that rats born to mothers fed genistein had decreased birth weights compared to controls and onset of puberty occurred earlier in male offspring.68 His research suggested that the effects observed in rats “…will be at least somewhat predictive of what occurs in humans. There is no reason to assume that there will be gross malformations of fetuses but there may be subtle changes, such as neurobehavioral attributes, immune function and sex hormone levels.” The results, he said “…could be nothing or could be something of great concern…if mom is eating something that can act like sex hormones, it is logical to wonder if that could change the baby’s development.”69

A study of babies born to vegetarian mothers, published in January 2000, indicated just what those changes in baby’s development might be. Mothers who ate a vegetarian diet during pregnancy had a fivefold greater risk of delivering a boy with hypospadias, a birth defect of the penis.70 The authors of the study suggested that the cause was greater exposure to phytoestrogens in soy foods popular with vegetarians. Problems with female offspring of vegetarian mothers are more likely to show up later in life. While soy’s estrogenic effect is less than that of diethylstilbestrol (DES), the dose is likely to be higher because it’s consumed as a food, not taken as a drug. Daughters of women who took DES during pregnancy suffered from infertility and cancer when they reached their twenties.

GRAS Status

Lurking in the background of industry whoopla for soy is the nagging question of whether it’s even legal to add soy protein isolate to food. All food additives not in common use prior to 1958, including casein protein from milk, must have GRAS (Generally Recognized As Safe) status. In 1972, the Nixon administration directed a reexamination of substances believed to be GRAS in the light of any scientific information then available. This reexamination included casein protein which became codified as GRAS in 1978. In 1974, the FDA obtained a literature review of soy protein because, as soy protein had not been used in food until 1959 and was not even in common use in the early 1970s, it was not eligible to have its GRAS status grandfathered under the provisions of the Food, Drug and Cosmetic Act.71

The scientific literature up to 1974 recognized many antinutrients in factory-made soy protein, including trypsin inhibitors, phytic acid, and genistein. But the FDA literature review dismissed discussion of adverse impacts with the statement that it was important for “adequate processing” to remove them. Genistein could be removed with an alcohol wash but it was an expensive procedure that processors avoided. Later studies determined that trypsin inhibitor content could be removed only with long periods of heat and pressure, but the FDA has imposed no requirements for manufacturers to do so.

The FDA was more concerned about toxins formed during processing, specifically nitrites and lysinoalanine.72 Even at low levels of consumption — averaging one-third of a gram per day at the time — the presence of these carcinogens was considered too great a threat to public health to allow GRAS status. Soy protein did have approval for use as a binder in cardboard boxes and this approval was allowed to continue because researchers considered that migration of nitrites from the box into the food contents would be too small to constitute a cancer risk. FDA officials called for safety specifications and monitoring procedures before granting of GRAS status for food. These were never performed. To this day, use of soy protein is codified as GRAS only for limited industrial use as a cardboard binder.

This means that soy protein must be subject to premarket approval procedures each time manufacturers intend to use it as a food or add it to a food. Soy protein was introduced into infant formula in the early 1960s. It was a new product with no history of any use at all. As soy protein did not have GRAS status, premarket approval was required. This was not and still has not been granted. The key ingredient of soy infant formula is not recognized as safe.

The Next Asbestos?

“Against the backdrop of widespread praise. . . there is growing suspicion that soy — despite its undisputed benefits — may pose some health hazards,” writes Marian Burros, a leading food writer for the New York Times. More than any other writer, Ms. Burros’ endorsement of a lowfat, largely vegetarian diet has herded Americans into supermarket aisles featuring soy foods. Yet her January 26, 2000 article “Doubts Cloud Rosy News on Soy” contains the following alarming statement: “Not one of the 18 scientists interviewed for this column was willing to say that taking isoflavones was risk free.” Ms. Burros did not enumerate the risks, nor did she mention that the recommended 25 daily grams of soy protein contain enough isoflavones to cause problems in sensitive individuals, but it was evident that the industry had recognized the need to cover itself.

Because the industry is extremely exposed. Contingency lawyers will soon discover that the number of potential plaintiffs can be counted in the millions and the pockets are very, very deep. Juries will hear something like the following: “The industry has known for years that soy contains many toxins. At first they told the public that the toxins were removed by processing. When it became apparent that processing could not get rid of them, they claimed that these substances were beneficial. Your government granted a health claim to a substance that is poisonous and the industry lied to the public to sell more soy.”

The “industry” includes merchants, manufacturers, scientists, publicists, bureaucrats, former bond financiers, food writers, vitamin companies and retail stores. Farmers will probably escape because they were duped like the rest of us. But they need to find something else to grow before the soy bubble bursts and the market collapses – grass-fed livestock, designer vegetables…or hemp to make paper for thousands and thousands of legal briefs.

Sally Fallon is the author of Nourishing Traditions: The Cookbook that Challenges Politically Correct Nutrition and the Diet Dictocrats, Second Edition 1999 (New Trends Publishing 877-707-1776 or 219-268-2601) and President of the Weston A Price Foundation, Washington, DC,

Mary G. Enig, PhD is the author of Know Your Fats: The Complete Primer for Understanding the Nutrition of Fats, Oils and Cholesterol 2000 (, President of the Maryland Nutritionists Association and Vice President of the Weston A Price Foundation, Washington, DC. The authors wish to thank Mike Fitzpatrick, PhD and Valerie & Richard James for their help in preparing this article.


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48. G Matrone et al, Effect of Genistin on Growth and Development of the Male Mouse, Journal of Nutrition, 1956, 235-240.

49. Y Ishizuki, et al, The effects on the thyroid gland of soybeans administered experimentally in healthy subjects, Nippon Naibunpi Gakkai Zasshi 1991 767: 622-629.

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59. C Hagger and J Bachevalier, Visual habit formation in 3-month-old monkeys (Macaca mulatta): reversal of sex difference following neonatal manipulations of androgen, Behavior and Brain Reserach 1991 45:57-63.

60. R K Ross et al, Effect of in-utero exposure to diethylstilbesterol on age at onset of puberty and on post-pubertal hormone levels in boys, Canadian Medical Association Journal, May 15m 1983 128:(10):1197-8.

61. Marcia E Herman-Giddens, et al Secondary Sexual Characteristics and Menses in Young Girls Seen in Office Practice: A Study from the Pediatric Research in Office Settings Network, Pediatrics April 1997, 99:(4):505-512.

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65. Helen Altonn, Too much tofu induces ‘brain aging,’ study shows, Honolulu Star-Bulletin, November 19, 1999.

66. Journal of the American Geriatric Society, 1998 46:816-21.

67. Daniel R Doerge, Inactivation of Thryoid Peroxidase by Genistein and Daidzein in Vitro and in Vivo; Mechanism for Anti-Thyroid Activity of Soy, presented at the November 1999 Soy Symposium in Washington, DC National Center for Toxicological Research, Jefferson, AR 72029.

68. Claude Hughes, Center for Women’s Health and Department of Obstetrics & Gynecology, Cedars-Sinai Medical Center, Los Angeles, CA.

69. Soy Intake May Affect Fetus, Reuters News Service, November 5, 1999.

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71. FDA ref 72/104, Report FDABF GRAS - 258

72. Evaluation of the Health Aspects of Soy Protein Isolates as Food Ingredients, Prepared for FDA by Life Sciences Research Office, Federation of American Societies for Experimental Biology, 9650 Rockville Pike, Bethesda, MD 20014, Contract No, FDA 223-75-2004, 1979.

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