Irritable Bowel Syndrome Message Boards | For parents of young children: Soy induced thyroid disease

There is a big difference between having problems with a food as a result of a medical disorder, and then making the assumption that the food itself caused the disorder in the first place. That's not necessarily true in most cases. I do think that whole food soy products (tofu, soy milk, edamame) have a great tradition and history as healthy additions to people's diets. Whether you can then take the soybean and process out all but the isolate soy protein, and then megadose on that extracted protein in a power bar or shake, is another matter. I like Kandee's analogy to high fructose corn syrup - you start with a healthy whole food like corn and end up with something so highly processed it has zero health benefits and actual possible detriments.

Soy is also being genetically modified now, and mass-produced. I would not trust these soybeans, and unfortunately in the US genetically modified foods don't have to be labeled as such. The solution is to stick organic soy products, which by definition cannot include genetically modified soy beans. The good news here is that many, many brands of soy milk and tofu are organic.

Soy does have a wealth of studies that support it as a food that reduces heart disease and osteoporosis. It's estrogenic effect also seems to be very beneficial to men and women. It's not comparable to taking birth control pills - the hormonal effects of soy come from phytoestrogens. They lock onto estrogen receptors in the body and as a result circulating human estrogen is displaced and excreted from the body. The lower estrogen levels in the body that result have clear health benefits - later onset of menstruation, lower breast, prostate, and ovarian cancer rates among them. Natural phytoestrogens and their effects just are not directly comparable to the synthetic estrogen (and progesterone, another hormone entirely) that are in birth control pills.

I'd be reluctant to make any assumptions for adult health based on the effects of soy formula on children. As you've noted, ANY formula is inferior to breast milk and the health consequences of formula-feeding are as likely to be from the lack of breast milk as from the addition of the formula itself.

I'm not sure what to think about the quote that Japanese only average 2T of soy consumption a day. I just don't think that sounds right, and it doesn't jive with studies I've seen on the Japanese diet and health effects. I'm trying to find accurate info on this - a quick google search turned up a statistic that:

"In most Asian countries the consumption of (soy) isoflavones is estimated as 25 to 45 mg per day. Japan has the highest consumption level, estimated at up to 200 mg per day. In western countries typical consumption is less that 5 mg of isoflavones per day." A 100-gram serving of tofu supplies about 30 mg isoflavones. So, this would be a significant daily amount of soy in the diet.

I also found this: "A recent panel of world experts (see Reference 1) determined that the amount of soy nutrients needed to achieve all of the potential benefits of soy, including a reduced risk of certain cancers, was in the range 100 to 160 milligrams of soy isoflavones per day.

Isoflavones are one of the natural nutrients found in soy protein and are believed to help produce many of soy's benefits for menopausal symptoms, PMS symptoms, cholesterol reduction, breast tissues and prostate tissues. This level of isoflavone consumption equates to eating 3 to 6 daily servings of traditional soy protein foods like soy milk or tofu. This seems like a lot, but the traditional, countryside Japanese diet includes 3 to 6 servings of soy foods. The amount of 150-200 milligrams of soy isoflavones per day has been published in the prestigious Obstetrics & Gynecology journal. (Reference 2)

A recent study in China revealed that the average daily soy protein consumption was 100 grams per day! (Reference 3) The latest Taiwanese study shows that Taiwanese children consume close to 40 milligrams of isoflavones per day. A single cup of regular soy milk can provide 30 to 40 milligrams of soy isoflavones, so we know that the traditional Asian diet, with 3 to 6 servings of soy foods, easily contains 150-200 milligrams per day. A small number of scientists and health magazines are quoted as saying that the Asians consume only 40-50 milligrams per day. This is in reference to metropolitan areas like downtown Tokyo where the diet is being "Westernized" (i.e. fast food restaurants are moving in). Interestingly, cancer rates are on the rise in Asian metropolitan areas where soy consumption is declining.

In summary, based on the soy consumption data from Asian countries and the recent panel of experts' recommendations, you should consume 3 to 6 servings of traditional soy foods per day for maximum benefits.

References: 1. Appropriate Isoflavone Food Fortification Levels: Results of a Consensus Conference. J.J.B. Anderson, H. Adlercreutz, S. Barnes, M.R. Bennink, M.S. Kurzer, P. Murphy, K. Setchell, C.M. Weaver, and C.M. Hasler. Univ. of No. Carolina, Helsinki, Ala.-Birmingham, Michigan St., Minnesota, Iowa St., Cincinnati, Purdue and Illinois. Experimental Biology 2000, San Diego, CA April 15-18, 2000.

2. The effect of dietary soy supplementation on hot flushes. Albertazzi P, Pansini F, and Bonaccorsi G, et al. 1998. Obstetrics & Gynecology. Jan;91(1):6-11.

3. Usual dietary consumption of soy foods and its correlation with the excretion rate of isoflavonoids in overnight urine samples among Chinese women in Shanghai. Chen Z, Zheng W, Custer LJ, Dai Q, Shu XO, Jin F, Franke AA. University of South Carolina, Columbia 29203, USA. Nutr Cancer 1999;33(1):82-7."

If I had a thyroid disorder or a family susceptibility to developing one, I'd be reading everything I could about soy to make sure it's a food I want to keep eating - and it may not be. Otherwise, I'd feel the health benefits are pretty well-established for soy, but I'd want my soy foods to be organic and as close to the whole bean as possible instead of some protein isolate soy power bar. Whole foods are always better, often in ways scientists haven't even figured out - but nature already has.

- Heather

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Heather is the Administrator of the IBS Message Boards. She is the author of Eating for IBS and The First Year: IBS, and the CEO of Heather's Tummy Care. Join her IBS Newsletter. Meet Heather on Facebook!

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