Do Soy Estrogens Act as Endocrine Disruptors?
Beside the estrogen-mimicking chemicals we are so routinely exposed to, there are also plant-derived estrogens, also called phytoestrogens (from the Greek word for plant—phyton).
I’m going to concentrate now on the widely used soy. There is quite a bit of information about soy having estrogen-like activity. The components from soy products linked to this effect are the isoflavones through their metabolite called equol. This is the compound that has the ability to bind to estrogen receptors and is generated after soy isoflavones are metabolized by intestinal microbial flora.
Having learned these details, it has been shown some people exposed to similar quantities of soy will generate more or less equal, depending on how they metabolize soy. It has also been described that people with East Asian descent have genetic adaptations to equol production, given their exposure to soy, which has been historically part of their diet.
Soy is used in infants’ formulas and in numerous other foods (tofu, soy milk, soy protein supplements, soy sauce, soy paste—miso, soy flour, soybean oil, soy nuts); soy lecithin is used as an emulsifier (in chocolate, baking mixes, salad dressings or margarine). Beside the wide range of uses in human foods, soy is widely used for animal feed (likely advertised as “vegetarian diet”), and the active metabolite can remain in the meat and consumed; more than 90 percent of the soybean crops in North America are from GMO seeds.
Other than its use in foodstuff, soy derived components have numerous other uses. Soy oil or soy wax (an alternative to paraffin wax), are used for candles, wrapping paper, crayons or ink; soy oil is also used for biodiesel fuel, solvents, lubricants, and other industrial applications for products which seem to be more environmentally friendly. There is increasing concern, however, about GMO soy and its widely used Roundup herbicide, because residues of its active ingredient—glyphosate—can end up in our body and environment (surface waters, rain and air), but it’s beyond the purpose of this blog post to get into more details about all these.
There are some reports that the estrogenic properties of soy isoflavones may be beneficial for hot flashes or for cardiovascular disease post-menopause. Other unproved benefits concern osteoporosis, protection against breast and prostate cancers, and even obesity, diabetes and others. Many of these effects may apply to Asian populations because of their adaptation to soy, but cannot be automatically extended to other populations.
The health benefits data are conflicting and more research is needed before it can be concluded the benefits outweigh the risks of them acting as endocrine disruptors.
In humans, the soy estrogens act as estrogen receptor modulators and is questionable if such modulations are desirable for infants who consume soy formula, older children or even adults with diets rich in soy products. In animal studies there are some reports about soy isoflavones impacting fertility in sheep and associated abnormalities of sexual development in rats.
After reviewing these facts about soy estrogens, I’m going to return to my susceptibility to foreign estrogens. When I have been exposed to them, usually the chemical ones, my first and and quite rapid sign of an adverse reaction is a migraine headache within 12-24 hrs. As I explained in the book, eliminating the estrogen-mimicking chemicals as much as I feasible, produced a dramatic reduction of the frequency and severity of such episodes.
Of course, I wondered if I was also getting migraine headaches from soy estrogens and my answerer is clearly NO.
I only consume soy occasionally, but given my experience with the other migraine triggers, I think I would be able to appreciate quite reliably if soy affects me as well. Because our family diet it’s mostly a whole foods American diet with some Eastern European influences, I don’t routinely use any of the soy products at home. Each time after we occasionally order Chinese food, or after eating in Korean or Japanese restaurants, I don’t experience any migraines. On a side note, I’m always pleased to notice that in these restaurants the food is cooked and served in glass, ceramic, cast iron or stainless steel; all these are safe for me, unlike teflon or aluminum, which never fail to trigger some of my migraines.
Maybe my lack of getting migraine headache from soy products has to do with the fact that I’m not an equol producer—the active metabolite—which is a more pronounced genetic trait of East Asian populations.
For all the migraine sufferers reading this, my suggestion is to pay close attention especially to all the soy-derived food products you use and notice if they trigger migraines. Given the genetic differences in metabolizing isoflavones to equol, it’s more likely that people of East Asian descent suffering of migraines may be more affected by these estrogens, compared to the populations not metabolizing them the same way. If that’s the case, you’re better off staying away from soy products, along with the other household items I described as possible migraine triggers.
Since soy products are not routinely part of my diet, I don’t have much of a reason to suspect they may have played a role in my abnormal breast tests.
If you are diagnosed with breast abnormalities and consuming soy, please ask the treating physicians if they would consider helpful to avoid soy products, especially if you have East Asian ancestry. North American Menopause Society (NAMS) recommends that women diagnosed with breast or endometrial (uterine) cancers consult with the oncologists before using any soy phytoestrogens /isoflavones products.