Is it safe to consume large amounts of soya protein?

Hi Catherine,

To say that women in Asia consume large amounts of soya protein simply is not true. Soya beans are rarely eaten in Asia because they are unpalatable and contain many anti-nutrients in their unprocessed state. In Asia, soya is consumed mainly in the form of fermented soya sauce. Less widely consumed, but also popular, is fermented miso, and tempeh. Tofu is eaten on a less than regular basis, usually as an addition to a meat-based dish, and soya milk is a grayish, watery liquid consumed infrequently. The thick, chalky type of soya milk consumed outside of Asia is not part of any traditional diet. Soya is being touted as the “miracle’ food by the researchers on the payroll of the Soya Industry’s extensive marketing board. I’ve lived in Asia and know that what I state about the traditional use of soya is that diet is true. Misinformation is easily repeated until its taken for the truth, and paradigms are hard to break. (~E.P.~)

I write to tell you that for a low thyroid woman, taking soy is detrimental to getting the thyroid to function well. I fear that if women taking progesterone with soy phytoestrogens in it don’t know that they are hypothyroid, they will make their thyroid condition worse which will also compromise their female hormones. (~Mindy~)

I wanted to add to the comments made about soy protein for helping with hot flashes. I was having very bad hot flashes and that “aura” feeling just before they hit in my head - not comfortable - and almost making me sick to my stomach. But I read about a product that claim they have been able to replicate the same soy protein that is in the diets of the Japanese women. Well, I tell you within a week of having a shake everyday around dinner time I have absolutely no more hot flashes. I’m sleeping fantastically at night - it’s incredible. (~Terri~)

Dear Ladies,

Challenging paradigms that do not serve us is what this newsletter is all about. So let’s examine more closely the pros and cons of soy in our diet.

Soy products contain “isoflavones”. These are plant compounds that have estrogen-like effects in the body. They are also called “isoflavonoids”, “flavonoids”, “lignans”, or “phytoestrogens”. Soy, however, isn’t the only food that contains isoflavones; tea, fruits, and vegetables also contain them.

Women may want to consume a sufficient amount of isoflavones to help regulate their estrogen levels. Using isoflavones is especially important for women who are estrogen-deficient and want to minimise or stop their use of estrogens foreign to the human body, such as those in Premarin.

Soy contains several naturally occurring compounds that are toxic to humans and animals. The soy industry frequently refers to these toxins as anti-nutrients, which implies that they somehow act to prevent the body getting the complete nutrition it needs from a food.

Soya’s high levels of phytic acid blocks the absorption of essential minerals in the digestive tract, putting vegetarians who eat soya as the major source of protein in their diet at severe risk of mineral deficiencies, including calcium, copper, iron, magnesium and especially zinc. To reduce the effects of a high-phytate diet, we need to eat, as the Japanese do, lots of meat or fish with tiny bits of soya.

The soy toxins (such as phytic acid) can certainly act in this manner, but they also have the ability to target specific organs, cells and enzyme pathways and their effects can be devastating. As with any toxin there will be a dose at which negative effects are not observed.

Soy Online Services have examined the scientific data on the soy toxins and have uncovered several alarming truths:

• There is no legislation to protect consumers from soy toxins in raw soy products.
• With the possible exception of soy lecithin, all soy products, no matter how well treated, contain low to moderate levels of soy toxins; processing cannot remove them all of any of them.
• The soy industry has little in the way of quality control to protect consumers from exposure to inadequately treated soy products.

In the last few years, interest in soybeans and soybean components has increased markedly, mainly because of the potential influence of soy on the development of heart disease, cancer, kidney disease, osteoporosis, and menopause symptoms. Unfortunately, soy protein formulas can cause allergies and other intolerance reactions. A general agreement has been reached that a significant number of children with cow?s milk protein intolerance develop soy protein intolerance when soy milk is used in dietary management.

A 1998 study showed that a Japanese man typically eats about 8g (2 tsp) a day, nothing like the 220g (8oz) that a Westerner could put away by eating a big chunk of tofu and two glasses of soya milk. Secondly, although Japanese people may have lower rates of reproductive cancers, this is thought to be due to other dietary and lifestyle factors: they eat less fatty meat, more fish and vegetables and fewer tinned or processed foods than in a typical Western diet. Thirdly, Asians have much higher rates of thyroid and digestive cancers, including cancer of the stomach, pancreas, liver and oesophagus.

A yearlong review of the available human studies in 1999 prompted the USA’s Food and Drug Administration (FDA) to allow a health claim on food labels stating that a daily diet containing 25 grams of soy protein, also low in saturated fat and cholesterol, may reduce the risk of heart disease.

Daniel Sheehan, Ph.D., director of the Estrogen Knowledge Base Program at FDA’s National Center for Toxicological Research, urged caution in consumption of soy isoflavones. In formal comments submitted to the public record of his own agency while FDA was reviewing the health claim, Sheehan, along with colleague Daniel Doerge, Ph.D., wrote, “While isoflavones may have beneficial effects at some ages or circumstances, this cannot be assumed to be true at all ages. Isoflavones are like other estrogens in that they are two-edged swords, conferring both benefits and risks.”

According the the National Library of Medicine, the soybean has been implicated in diet-induced goiter by many studies. In this report, it was observed that an acidic methanolic extract of soybeans contains compounds that inhibit thyroid peroxidase (TPO) catalyzed reactions essential to thyroid hormone synthesis.

Mary Shomon, author of the highly acclaimed publication Living Well With Hypothyroidism makes the following comments, “My primary concern with soy products is for people who are already hypothyroid due to autoimmune thyroid disease, or those who are from a family with a history of autoimmune thyroid disease.

“In those people, over-consumption of soy products (here I’m most worried about soy supplements, isoflavone pills, and so-called “menopause” aids like Revival or Promensil) may worsen their thyroid problem, or trigger a problem in someone not yet diagnosed. I also caution those who are having trouble regulating their TSH levels to look at the quantity of soy.

“That said, I think for those without autoimmune problems, and those who can eat soy while remaining regulated and going well on their thyroid medications, its not a problem. And even those with autoimmune thyroid disease can benefit from some soy in their diet … I eat soy burgers, soy patties, and some tofu and miso periodically. I’m just not going to take soy powers or pills.”

The risk of thyroid disease is particularly great for infants on soy formula.

It is estimated that an infant exclusively fed soy formula receives the estrogenic equivalent of at least five birth control pills per day. By contrast, almost no phytoestrogens have been detected in dairy-based infant formula or in human milk, even when the mother consumes soy products. A recent study found that babies fed soy-based formula had 13,000 to 22,000 times more isoflavones in their blood than babies fed milk-based formula.

Most parents feeding soy formulas still have absolutely no idea that they contain these potent endocrine disrupting compounds, and by not disclosing the presence of phytoestrogens in their products, soy formula manufacturers are in violation of the WHO code of marketing breast-milk substitutes.

In a paper published in the New Zealand Medical Journal (Volume 113, Feb 11, 2000), environmental scientist and long-time campaigner against soy-based infant formulas, Dr Mike Fitzpatrick, has warned about the risk of thyroid disease in infants fed soy formulas, high soy consumers and users of isoflavone supplements:

“There is potential for certain individuals to consume levels of isoflavones in the range that could have goitrogenic effects. Most at risk appear to be infants fed soy formulas, followed by high soy users and those using isoflavone supplements”.

The report noted that infants fed soy formulas are exposed to high levels of isoflavones, which are potent anti-thyroid agents, and that the risks to normal growth and development were significant.

Fitzpatrick stated that thyroid problems due to soy might not be recognised “due to difficulties in establishing a cause and effect relationship” and noted that even experienced soy researchers may be ignorant of the connection between isoflavones and goiter. Fitzpatrick also rejected claims that there was no evidence that isoflavones in soy formulas harmed infants, citing the reported cases of goiter that have occurred in infants fed iodine sufficient soy formulas.

Fitzpatrick recommended “a more cautionary approach to the use of soy and isoflavone supplements”.

Soy foods can be important as one part of a balanced nutrition and lifestyle approach to menopausal symptoms but they aren’t a solution by themselves says Dr. David Zava, a Biochemist Research Scientist who, over the past 25 years, has published extensively on clinical research relating to the effects of estrogen and progesterone on breast cancer.

He argues that even high consumption of soy isolates that are loaded with isoflavones only suppresses menopause symptoms minimally for most women. “The positive side of the study was that the intensity of hot flashes was reduced; however there was no statistical difference in the number of hot flashes these women were having. With natural progesterone and/or estrogen replacement therapy women often get complete relief of menopausal symptoms. Because the natural hormones are safe and effective when used properly, I think the push to use soy is the wrong approach, and is seriously compromising the health and quality of life of millions of women.”

So how much soy is safe? According to the Soy Online Services, for infants any soy is too much. For adults, just 30 mg of soy isoflavones per day is the amount found to have a negative impact on thyroid function. This amounts of soy isoflavones is found in just 5-8 ounces of soy milk, or 1.5 ounces of miso.

Modest soy intake also has other potential benefits. For example, Dr Nicholas Calvino wrote in his article The Truth About Cancer: Why We Must Return to Natural Diet & Nutrition, “Simple dietary changes equal profound changes in our health. For example, the combination of eating five servings of fruits and vegetables each day, moderately exercising, and eating one serving of soy per day, can possibly reduce your risk of cancer by 80%.”

Dr John C Lowe, a well known authority on thyroid function, believes that the phytoestrogens in soy, when used in moderation, can benefit many people.

In their publication Your Guide to Metabolic Health Drs John C Lowe and Gina Honeyman-Lower write, “Thanks to some of the our fine corporations, many - perhaps most - people today are estrogen dominant. Despite this, however, some women have estrogen deficiencies. We prefer that these women relieve their estrogen deficiencies with modest amounts of phytoestrogens than to brutalize themselves biochemically with products such as Premarin.

“We agree that many people consume too much soy, and anyone who consumes genetically-modified soy foolishly risks his health. But we also feel that it?s important to keep a balanced view in this matter: Consuming modest amounts of soy foods that haven?t been genetically modified can provide some health benefits. We therefore support the sensible use of soy.”