Soy, Its Benefits
and its Surprising Risks

By Annemarie Colbin, Ph.D., Ches

I started using soy products in the 1960’s. Mostly I used naturally fermented traditional soy sauce (which in those days used to be called “tamari” to distinguish it from the mass-produced and flavored quickie commercial soy sauce). Tofu was a very new product, and little by little it migrated from Chinatown to the New York lower East Side to the kitchens of health-conscious consumers.

I made my own tofu a couple of times, but that was a huge amount of work and I think I ended up with about ¼ cup of tofu from 4 cups of soybeans. Not worth it, to make it at home. I gave the homemade soymilk to one of my daughters, about age 8 at the time, and it made her throw up immediately. So—scrap that one. I just bought the pre-made kind.

I loved the naturally fermented, unpasteurized aged miso, not just for the classic miso soup but also as a terrifically flavored ingredient in sauces and salad dressings. In fact, I once attended a class with Naburo Muramoto (author of Healing Ourselves), where we made home-made miso—we set it up, and then it was finished 8 months later. Fabulous stuff! That was an experiment that worked, although I didn’t repeat it because I can just as well buy really good organic miso in any health food store today.

Tempeh didn’t become a known item until sometime in the late ’70’s or early 1980’s. I did make my own a few times, which was good but a lot of work. As both a whole food and a fermented soy product, I found it really appealing, except it needed serious seasoning to get rid of that particular tang that it has when raw. I ended up with a vegieburger I really liked (see below), and almost went into business with it, except life took me elsewhere.

The soy products were a way to get good vegetable protein into a plant-based diet. Miso was considered an immune booster in the natural health community. When science caught up with traditional knowledge, some ingredients were discovered in soy that were believed to enhance the immune system, prevent cancer, and help the female reproductive system. I remember running into a nutritionist in the late 1980’s and she stopped me and said “Did you know that miso contains GENISTEINS?” I had no idea what that meant at the time, but she was very thrilled about it. I figured, as long as it gets people to eat some miso, that is fine with me.

Since the late 1980’s there has been a great deal of emphasis on using soy for the health issues of women. Curiously enough, that is also about the time that soybeans began to be genetically engineered. I always found this timing coincidence curious.

Regular (non-GMO) soybeans are known to contain both phytoestrogens and goitrogens. Phytoestrogens (genistein is one of them) are similar to the female hormone estrogen, and thus they can have both positive and adverse effects. They may diminish hot flashes in post-menopausal women; on the other hand, studies with rats suggest that when taken by pregnant women, genisteins may adversely affect the reproductive system of their developing male and female embryos, an adverse effect that may manifest into adulthood as reproductive system disorders. (Jefferson, Padilla-Banks et al. 2007; Vilela, Willingham et al. 2007)

A 2007 study from the University of Goettingen, Germany, about the effects and risks of phytoestrogens or isoflavones, has the following comment: “When administered to...women at the time of menopause, the phytoestrogens appear to share the same effects as estrogen used in classical preparations for hormone replacement therapy, i.e. they may stimulate the proliferation of endometrial and mammary gland tissue with at present unknown and unpredictable risk to these organs.” (Wuttke, Jarry et al. 2007) Soy products are recommended against osteoporosis because the assumption is that, being estrogenic, they will have a positive effect on bone mineral density, although that does not mean that they prevent fractures.

The presence of goitrogens—substances that weaken the thyroid—in soy has been known for at least 30 years. I mentioned that in my book Food and Healing (Ballantine 1996), the first edition of which was published in 1986. This is an issue that is mostly overlooked in the great soy marketing push: soy does weaken the thyroid. For clients who come to me for consultation, if they have any thyroid issues, I will suggest that they completely avoid any kind of soy, with generally good results. In addition, as a legume, soy in its uncooked state contains substances called trypsin inhibitors, also called proteinase inhibitors. These substances interfere with the protein-digesting activity of the digestive enzymes trypsin and chymotrypsin. Animals fed raw soybean meal show reduced growth and extensive damage to the pancreas. Cooking helps eliminate most of the trypsin inhibitors. Therefore, tofu and soy milk, which are uncooked, are poor food choices, both for children—they may cause stunted growth—and adults.

It is important to remember that at this time (in the first decade of the 21st Century), about 89% of the soy crop in the United States is GMO, or genetically engineered, most commonly to resist an herbicide. Studies on mice show that when fed GMO soy, there are unfavorable changes in the liver, pancreas, and testes of the laboratory animals. When these animals were switched off the GMO soybeans and fed the standard non-GMO soy, their organs returned to normal (Smith 2007).

To be safe, if you are using soy products, it’s essential that they be organic, non-GMO, and fermented, such as tempeh, natto, and soy sauce. I think it’s OK to use tofu here and there, mixed into stir-fry’s or other dishes, but not too much. I really don’t like soy milk as a dairy substitute; it’s just a white liquid, like milk is, but highly processed. Real homemade soy milk tastes like bean water, which it is. The commercial stuff has a lot of ingredients in it, including sweeteners—just read the label carefully. While I have met women who feel that their hot flashes have diminished from drinking soy milk, as a whole I would advise against uncooked, unfermented commercial soy as a healthy food, because of all the other problems mentioned.

REFERENCES

Jefferson, W. N., E. Padilla-Banks, et al. (2007). ”Disruption of the developing female reproductive system by phytoestrogens: genistein as an example.” Mol Nutr Food Res 51(7): 832-44.

Smith, J. M. (2007). Genetic Roulette: The Documented Health Risks of Genetically Engineered Foods. Fairfield, IO, Yes! Books.

Vilela, M. L., E. Willingham, et al. (2007). ”Endocrine disruptors and hypospadias: role of genistein and the fungicide vinclozolin.” Urology 70(3): 618-21.

Wuttke, W., H. Jarry, et al. (2007). ”Isoflavones--safe food additives or dangerous drugs?” Ageing Res Rev 6(2): 150-88.

Illustration by Rachel Carns