October 1st, 2002 | Published in 2002 rants
This weekend I was shopping at the local market. I got hungry and wanted a protein bar.
I popped into a health food store which I know sells them. I was confronted with a floor to ceiling rack of bars. I stood reading the labels.
Soy. Soy. Some weird grains and shit. Soy. Nuts and twigs. Soy. Carb-A-Lot. Soy. Soy. Soy.
Can’t a woman get some plain whey any more?
I left without buying anything. As we were leaving, I said to the friend who was with me, “Dammit, all they have is that soy crap!”
She said, “Soy is the new hemp.”
In other words:
Soy is the new “Super Ingredient” in food products.
It’s everywhere: soymilk, soy cream, soy cheese, soy nuts, soy chips, soy bars, tofurkey, soysauges, soyloney, probably soy freaking candies somewhere.
Soy is supposedly good for women.
Soy is the Messiah.
Soy will save us from illness and existential trauma.
Soy slices and dices.
Soy is the new hemp, which was the new olive oil, which was the new oat bran, which was the new fat free.
But wait a minute.
Soy ain’t all it’s cracked up to be.
Soy contains phytoestrogens.
These are plant chemicals that act like estrogens in humans. This is why some people tell menopausal women to take soy.
However, messing with your hormones randomly and without a standardized dose can be dicey. When combined with other sources of estrogens like HRT or oral/injected contraceptives, or xenoestrogens from environmental chemicals,that’s a crapton of estrogenic molecules floating around in your body.
Soy has been implicated in thyroid problems.
Soy can worsen existing thyroid dysfunction symptoms, and trigger an unnoticed thyroid condition. It can affect the production of important thyroid hormones.
Given that many people, especially women, have an undiagnosed and/or subclinical thyroid problem, this is significant indeed.
The thyroid plays a major role in helping us maintain a healthy weight and body composition.
If it goes out of whack, you can start piling on body fat and losing lean mass.
Soy isoflavones, taken in sufficient quantities, will stimulate breast growth in males.
(I’ve seen do-it-yourself breast growth in male-to-female transsexuals who used soy to do it).
An interesting study from Germany looked at soy versus casein protein in rats. The rats who were fed the soy formula had a lower rate of energy expenditure, aka a slower metabolism (bear in mind, though, that humans aren’t rats).
Soy contains antinutrients.
These are substances that interfere with the digestion or absorption of other things, such as minerals or proteins.
Antinutrients include protease inhibitors (stuff that blocks proper protein breakdown) and lectins (plant proteins that can cause intestinal damage).
Soy is one of the top food intolerances or allergens.
The Food and Agriculture Organization of the United Nations (FAO) includes soy in its list of the 8 most significant food allergens.
Soy intolerance — with milder symptoms such as stomach upset, skin issues, etc. — is subtler but still relatively common.
Foods have a context.
You can’t just randomly grab shit from some other region’s cuisine without understanding how that food (or ingredient) fits into the cultural, social, and culinary context.
In other words:
You have to look at the big picture.
Among cultures who traditionally consume soy:
- How is that soy prepared?
- How do they eat it?
- In what amount?
- With what other foods?
- Who eats it?
I’ve traveled in Asia and spent time in Japan, the oft-cited Mecca of soy consumption and supposedly vibrant good health.
Traditional methods of soy processing in Eastern Asia usually involve extensive processing to decrease antinutrients and improve the nutritional value.
Soy is almost always traditionally soaked, cooked, and fermented.
Nobody eats straight-up mature soybeans, which, like many other mature legumes, are toxic when improperly prepared. However, edamame (cooked immature green soybeans) are a popular snack (in small amounts).
Miso is traditionally made by cooking soybeans then colonizing them with Aspergillus oryzae, a mould that naturally grows on rice. Soybeans would be planted along with rice crops to fix nitrogen in the soil; the rice mould would then help to ferment the soy.
Tempeh is traditionally made in a similar way — Rhizopus oligosporus or Rhizopus oryzae is the fungus used. During the fermentation process, other bacteria such as Citrobacter freundii or Klebsiella pneumonia also appear, and help produce vitamin B12, along with other vitamins.
Natto — which, by the way, most North Americans think is disgusting (although I love it) — is fermented with a bacterium — Bacillus subtilis var. natto.
Almost all ancestral preparations of soy are slow, methodical, organic processes that depend on the biological effects of naturally occurring fungi or bacteria.
Modern soy preparations are different, now depending on industrial processes.
Soy is traditionally eaten in small amounts.
People in Eastern Asia don’t eat tempeh bacon washed down with a soy latte.
Soy is a condiment or a flavour agent, not the main event.
For instance, here are some average amounts of phytoestrogens (daidzein and genistein) in processed vs traditional foods.
- Meatless bacon bits: 64 mg of daidzein and 46 mg of genistein per 100 g.
- Soy milk: 28 mg daidzein and 43 mg genistein per 100 g.
- Miso: 16 mg daidzein and 23 mg genistein per 100 g.
Now, let’s think about how you’d eat these foods.
1 cup, or 8 ounces, of soy milk is 226 grams, which gives you 242 mg of phytoestrogens in total.
Meanwhile, you might put only a tablespoon or two of miso paste into an entire batch of soup. So let’s call that about 25 grams per serving — which gives you just under 10 total mg of phytoestrogens.
See the difference?
Indeed, studies show that traditional Japanese intakes are around 10-25 mg of soy-derived phytoestrogens per day… less than 10% of our one soy latte.
Soy is traditionally often eaten with other foods.
These foods may balance out soy’s chemical composition.
For instance, folks in Japan eat a fair bit of seaweed, which provides valuable minerals such as iodine.
Who eats soy may be important.
The effects of soy may vary by:
- age and stage of sexual development (e.g. pre-pubertal, pubertal, premenopausal, menopausal, etc.)
- sex and hormone status (in other words, is there supposed to be lots of estrogen in your system?)
- genetics and ethnicity (e.g. do people whose ancestors traditionally ate soy digest or tolerate it differently than those who didn’t?)
In other words:
Soy isn’t a magic ingredient.
Moderate consumption of soy, particularly traditionally prepared forms of fermented soy (such as natto) may have some benefits for some things in some people, but mounting evidence suggests that overconsumption of soy can be a problem.
Now, I’m not saying that you have one slice of tofu and immediately grow a goiter.
The problem is the amount of soy — especially processed soy — consumed.
If you push soy products into your gob in large quantities several times a week, you could be in for problems.
If you have the occasional tofu hot pot at your favourite Szechuan restaurant, then you’re probably fine.
Soy is not safe simply because it is natural, and it is not a cure for everything that ails you.
We tend to clutch superstitiously at food fetishes, and get myopic in our desire to eat well.
We look to one food to be magical.
In this well-meaning endeavour, we miss balance and moderation.
Soy will not save you from the boogeyman, so put the soy bacon back and jeez, have something that actually might taste good.
(This article was originally written in 2002. I’ve since updated some of the references as more current research becomes available.)
Adlercreutz H, Yamada T, Wahala K, Watanabe S. Maternal and neonatal phytoestrogens in Japanese women during birth. Am J Obstet Gynecol. 1999;180:737–43.
Daniels, Kaayla. The Whole Soy Story.
de Azevedo Elaine. Risks and controversies in the social construction of the concept of healthy food: the case of soy. Rev Saude Publica. 2011 Aug;45(4):781-8.
Dinsdale EC, Ward WE. Early exposure to soy isoflavones and effects on reproductive health: a review of human and animal studies. Nutrients. 2010 Nov;2(11):1156-87.
Fukutake M, Takahashi M, Ishida K, Kawamura H, Sugimura T, Wakabayashi K. Quantification of genistein and genistin in soybeans and soybean products. Food Chem Toxicol. 1996;34:457–61.
Jefferson WN. Adult ovarian function can be affected by high levels of soy. J Nutr. 2010 Dec;140(12):2322S-2325S.
Jefferson WN, Patisaul HB, Williams CJ. Reproductive consequences of developmental phytoestrogen exposure. Reproduction. 2012 Mar;143(3):247-60.
Keith, Sylvia and Bernward Bisping. Vitamin B12 production by Citrobacter freundii or Klebsiella pneumoniae during tempeh fermentation and proof of enterotoxin absence by PCR. Applied and Environmental Microbiology 60 no.5 (May 1994): 1495-1499.
Kurzer MS. Hormonal effects of soy in premenopausal women and men. J Nutr. 2002;132:S570–3.
Levis Silvina, Griebeler ML. The role of soy foods in the treatment of menopausal symptoms. J Nutr. 2010 Dec;140(12):2318S-2321S.
Lodge CJ, Allen KJ, Lowe AJ, Dharmage SC. Overview of evidence in prevention and aetiology of food allergy: a review of systematic reviews. Int J Environ Res Public Health. 2013 Nov 4;10(11):5781-806.
Maskarinec G. The human mammary gland as a target for isoflavones: how does the relation vary in individuals with different ethnicity? Planta Med. 2013 May;79(7):554-61.
Nagata C, Takatsuka N, Inaba S, Kawakami N, Shimizu H. Effect of soymilk consumption on serum estrogen concentrations in premenopausal Japanese women. J Natl Cancer Inst. 1998;90:1830–5.
Nakamura Y, Tsuji S, Tonogai Y. Determination of the levels of isoflavonoids in soybeans and soy-derived foods and estimation of isoflavonoids in the Japanese daily intake. J AOAC Int. 2000;83:635–50.
Reinli K, Block G. Phytoestrogen content of foods: a compendium of literature values. Nutr Cancer. 1996;26:123–48.
Reinwald S, Akabas SR, Weaver CM. Whole versus the piecemeal approach to evaluating soy. J Nutr. 2010 Dec;140(12):2335S-2343S.
Whitten PL, Lewis C, Russell E, Naftolin F. Potential adverse effects of phytoestrogens. J Nutr. 1995;125:S771–6