Monday, April 25, 2011

Soy vey!


A few readers and friends (NB and MBS among them) have asked me to write a bit about my thoughts on soy, and the general health benefits/costs associated with the food itself, rather than only with the “meat substitutes” that are sometimes made from soy, and which I’ve written about previously.

A year or so ago, one of my good friends SF asked me for my views about soy, and this is what I wrote at the time: “As for soy, I guess I generally like to follow the Michael Pollan approach to food: if it came from a plant, eat it; if it was made in a plant, don’t. So, although I know there's lots of uncertainties about the health benefits/harms of soy, I guess I think that minimally processed, organic, non-GMO soy products are fine in moderation, until I get further evidence that I should stop eating them. But I have started trying to stay away from things like TVP, soy nuggets, and other super-processed sorts of soy foods (though locally-made soy milk and tofu stay on my good list). My go-to nutritionists (Marion Nestle, Andrew Weil, Walter Willett, and Michael Pollan [if he counts!]) give a thumbs sideways, thumbs up, thumbs sideways, thumbs sideways, respectively, I think.”

I mostly still stand by my thoughts of last year, but figured I’d elaborate a little for the purposes of this blog post, to at least provide some more resources on the views of those “go-to nutritionists” of mine.

Despite all the claims that soy is either a super-food (Complete protein! Lowers cholesterol! Lots of fiber! Prevents bone loss!) or the devil (Causes breast cancer! Prevents absorption of essential minerals!  Suppresses thyroid function), it seems like it’s not really either, and that this general approach of thinking of food as medicine (or a harmful drug) is itself flawed.

So, whenever I have a nutrition-related question, I usually turn to Michael Pollan (author,  activist, professor of journalism at UC-Berkeley), Marion Nestle (Professor of Nutrition, Food Studies, and Public Health at NYU), Walter Willett (Chair of the Department of Nutrition at Harvard), and Andrew Weil (Author and Physician, founder and Program Director of the Arizona Center for Integrative Medicine), in that order. Here are their takes:

From Michael Pollan, Sustainable Eating & Nutrition
Verdict: Thumbs Sideways

  
“Americans are eating more soy products than ever before, thanks largely to the ingenuity of an industry eager to process and sell the vast amounts of subsidized soy coming off American and South American farms. But today we’re eating soy in ways Asian cultures with a much longer experience of the plant would not recognize: “Soy protein isolate,” “soy isoflavones,” “textured vegetable protein” from soy and soy oils… Until those data come in [on the estrogenic effects of soy], I feel more comfortable eating soy prepared in the traditional Asian style than according to novel recipes developed by processors like Archer Daniels Midland. For more on soy see In Defense of Food, section III.”


 From Marion Nestle’s What to Eat, Chapter 12.
Verdict: Thumbs Sideways

“At the moment, I find it impossible to make sense of the health debates about soy foods, not least because so much of the research is sponsored by industries [Cargill, Archer Daniels Midland, and USDA among them] with a vested interest in its outcome…They are just a food, one that you can choose to eat or not as a matter of personal preference. Soybeans and the minimally processed foods made from them make sense to eat but the principal result of the approval of the soy health claim has been the massive proliferation of processed soy products that can labeled with that claim.”


From Walter Willet, Eat, Drink and be Healthy as cited here
Verdict: Thumbs Sideways

Soy food may have a dark side "because estrogens play a role in maintaining normal mental function, and it is possible that too much antiestrogen in the wrong place at the wrong time could be harmful." But the bottom line is that he agrees that soy is a good alternative to animal protein, that it may lower the risk of heart disease and have other beneficial effects. “Just don’t overdo it,” he says. “Two to four servings a week of a soy-based foods such as tofu or soy milk is a good target.

From Andrew Weil: Rethinking Soy?
Verdict: Thumbs Up

“I'm aware of Internet paranoia on the subject of soy and the contention that only fermented soy is safe to consume. That is simply not true. Some of the best forms of soy—edamame, tofu and soy nuts—are unfermented and are much more likely to help you than hurt you…All told, based on the evidence to date, I see no reason to worry about eating soy foods, whether fermented or not. I still recommend consuming one to two servings of soy per day, an amount equivalent to one cup of soy milk, or one half cup of tofu, soy protein (tempeh) or soy nuts.”


So, for now, I'm sticking with soy (of the non-GMO, organic variety), but in moderation.  Other favorite nutritionists or guides or relevant research any of you have to offer?
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Resources/Other interesting takes:

8 comments:

  1. After reading The Vegetarian Myth, I was slightly freaked out by all the soy floating around Korea. At my school cafeteria, I'd say about half of the vegan entrees include tofu, as do about half of the soups. I'm sure very little of it is organic, though domestic tofu is growing in popularity; I have no idea whether it's GMO or not.

    Either way, I was listening to some vegan podcast - I can't remember which - and the speaker went to great lengths to say that SOY IS JUST A BEAN. It's not a miracle food (whatever that means), nor is it poison. There are cultures that have existed without it, and cultures that have made fairly extensive use of it, chance are it's neither necessary nor extremely harmful. As long as it's consumed in reasonable quantities and in something resembling its natural form, it's likely to fit in as a part of a balanced diet.

    So, I don't fret when there are a few tofu cubes in my soup, and I don't get too excited when I see a deep-fried soy cutlet on the menu at the local vegan fast food joint. Ehrm...that's my soylution?

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  2. Curious... what makes soy milk (/tofu) count as "minimally" processed?

    yours in procrastination (I'd rather be talking to you),
    H

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  3. Thanks for posting this Anna! I've seen soy based products (i.e., soybean oil, soy flour, soy lecithin) in so many ingredients' lists. It seems like it is everywhere! I've also heard about the influence it has on estrogen and have always wondered whether or not that was true. I'm going to take a closer look at the resources you recommended. Also, what is different about how soy is made/used in Asian cuisine than in American cuisine? --NB

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  4. I love your soy-lution, Mike! (Mike?! Who's that?)

    And I think both H and NB's very good questions can be answered by the same pieces of information that I neglected to include in my original post.

    As Andrew Weil writes in the Rethinking Soy? piece linked above "the idea is that high levels of isoflavones, active ingredients in soy that behave like estrogen in the body, may increase the risk of breast cancer. While high levels of isolated isoflavones may do so, it appears that the total mix of weak plant estrogens in soy protects the body's estrogen receptors. This protection may reduce the effects of excess estrogen exposure from such external sources as meats and dairy products from hormone-treated cows as well as artificial chemicals and industrial pollutants that act as foreign estrogens.”

    So, the way that soy milk and tofu (traditional Asian preparations of soy) are produced typically does not isolate isoflavones or other components, but leaves them in their usual weaker state in the total mix of the other soy components. The “American” way of preparing soy, however, typically leads to industrial manipulation of the soybean to extract various building blocks—like the soybean oil, soy flour, and soy lecithin that NB mentioned—to include as the base for other processed foods (that may or may not themselves be marketed as soy products—depending on whether the isolated isoflavones are simply being added to other foods, or if the soy components are re-processed into meat substitutes with 23 ingredients, like the Boca burger).

    I guess a simple way to think about the Asian/minimally-processed soy preparations are that they are things you could easily do in your own home with a cookbook and they have no more than 2-3 ingredients (like tofu or tempeh or soymilk), whereas American-style/highly-processed soy preparations could only be made in a factory, and have long ingredients lists, like the Boca burger.

    Does that make sense?

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  5. Interesting article! Thanks for posting :)

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  6. indeed it does make sense! it also makes me mighty curious to know how in the world soymilk or tofu can be made at home.

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  7. Thanks Anna! I noticed that even something as simple as bread has these soy isoflavones in it. It makes me mad that they add all this unnecessary stuff which can have negative health consequences. My search for better bread (and other products) will continue...
    -NB

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  8. Ooh! Homemade soy milk and tofu are two things I really want to try my hand at, so perhaps I'll put up some posts about my attempts later this summer.

    In the mean time, check out Mark Bittman's "How to Cook Everything Vegetarian," p. 657 ( available online at Google Books , though the previous page, which just includes the ingredient 1 gallon soy milk, is unavailable as a preview). Or this blog on making soy milk and on making tofu .

    Soy milk is pretty straightforward. You buy dried soybeans, soak to soften them, blend them up with water and cook them until the fibrous part separates from the rest of the bean. Then you strain the fibrous part (called "okara") away, and you're left with fresh soy milk!

    The basic idea of making tofu is very much like making cheese. You mix the soy milk with some sort of coagulant (Bittman offers everything from distilled vinegar to lime juice to the more traditional nigari, which is derived from seawater) and heat it until the curd separates from the whey. Then you press the curds until they form into a cohesive block. Voila, tofu!

    Can't wait to try it...

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