Myths and Truths About Soy

Soy is not the health food that we were led to believe that it was. Modern soy foods are far from healthful. Read these myths and truths about soy. Are you surprised? 

Myths and Truths About Soy

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 China is 10 grams (about 2 teaspoons) per day and up to 60 grams in parts of Japan. 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, soybeans 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 lowers one’s risk of developing heart disease. (to the contrary, actually)

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 mg isoflavones (from about 30 g soy protein) 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 lowers testosterone levels in men. Tofu was consumed by Buddhist monks to reduce libido.

Myth: Soybeans are good for the environment.
Truth: Most soybeans grown throughout the world are genetically engineered to allow farmers to use large amounts of herbicides, creating toxic runoff.

Myth: Soybeans 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.

Source: Weston A Price Foundation

  • I am with you on Soy not being the cure-all. I especially loathe all those supposedly-“healthy” soy-based meat substitutes and other faux food. But I’m curious about some points you raise here, and am asking for some documentation on the following:

    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 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.

    I know your rebuttal to the second part of the second myth is true (I regularly eat organ meat and use bones in soups), but curious about the soy deficiency connection.

    I eat edamame (soy) beans, from a trustworthy non GMO source, and I probably eat the equivalent of 3 packages of tofu a year. And one of tempeh.

  • I am with you on Soy not being the cure-all. I especially loathe all those supposedly-“healthy” soy-based meat substitutes and other faux food. But I’m curious about some points you raise here, and am asking for some documentation on the following:

    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 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.

    I know your rebuttal to the second part of the second myth is true (I regularly eat organ meat and use bones in soups), but curious about the soy deficiency connection.

    I eat edamame (soy) beans, from a trustworthy non GMO source, and I probably eat the equivalent of 3 packages of tofu a year. And one of tempeh.

  • Hi Diann,

    Thanks for your comment. I was surprised by many of the facts when I first heard them as I, too, had been consuming unfermented soy products, including edamame. I now only consume FERMENTED soy products- like natto, miso and tempeh and very small amounts of naturally fermented soy sauce (or tamari which is wheat free). I keep my soy intake to an absolute minimum however, since I am challenged with thyroid issues.

    Just to be clear, I did not write these truths/myths- as the source lists, it’s from the Weston A Price Foundation (www.westonaprice.org), a nutritional advocacy group that I support and follow for their excellent resources and research.

    It is my understanding that the deficiency occurs when the body is trying to digest and assimilate the unfermented soy and that B12 is somehow involved in that process, thus depleting your body’s reserves. The same for the other deficiencies (calcium, etc). The phytates in soy (which has the highest content of any other foods) block nutrient absorption in the intestines.

    On the WAPF website, they have further Soy Health related articles, including this one http://www.westonaprice.org/soy-alert/689-ploy-of-soy.html which is a bit more in depth than this list. Additionally, Dr Mercola has written extensively about this (www.mercola.com, just search for “soy”) and Dr Kaayla Daniel’s book, “The Whole Soy Story” is certainly worth a read. Besides the GMO issue (which you are obviously aware of already) there are rampant anti-nutrients in the form of phytates in the edamame as well as other factors that are harmful to your thyroid. I advise all of my clients, especially those with thyroid issues, to strictly limit soy intake and to completely avoid all unfermented soy.

    Hope this helps!
    Amy 🙂

  • Hi Diann,

    Thanks for your comment. I was surprised by many of the facts when I first heard them as I, too, had been consuming unfermented soy products, including edamame. I now only consume FERMENTED soy products- like natto, miso and tempeh and very small amounts of naturally fermented soy sauce (or tamari which is wheat free). I keep my soy intake to an absolute minimum however, since I am challenged with thyroid issues.

    Just to be clear, I did not write these truths/myths- as the source lists, it’s from the Weston A Price Foundation (www.westonaprice.org), a nutritional advocacy group that I support and follow for their excellent resources and research.

    It is my understanding that the deficiency occurs when the body is trying to digest and assimilate the unfermented soy and that B12 is somehow involved in that process, thus depleting your body’s reserves. The same for the other deficiencies (calcium, etc). The phytates in soy (which has the highest content of any other foods) block nutrient absorption in the intestines.

    On the WAPF website, they have further Soy Health related articles, including this one http://www.westonaprice.org/soy-alert/689-ploy-of-soy.html which is a bit more in depth than this list. Additionally, Dr Mercola has written extensively about this (www.mercola.com, just search for “soy”) and Dr Kaayla Daniel’s book, “The Whole Soy Story” is certainly worth a read. Besides the GMO issue (which you are obviously aware of already) there are rampant anti-nutrients in the form of phytates in the edamame as well as other factors that are harmful to your thyroid. I advise all of my clients, especially those with thyroid issues, to strictly limit soy intake and to completely avoid all unfermented soy.

    Hope this helps!
    Amy 🙂

Comments are closed.