Zen Habits: stupid about soy


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Isn't it cute when scientifically ignorant people accuse other people of being scientifically ignorant? You know they are scientifically ignorant because they blather on about "peer reviewed research" while obviously never having read any.

I don't know when or why I subscribed to the mindless platitude drivel blog Zen Habits, but their recent post about soy caught my eye.

It’s one of those things that has spread on the Internet and unbelievably, has become accepted truth to many people: that soy is unhealthy, even dangerous. I mention (to otherwise smart and informed people) that I drink soymilk sometimes, and a look of pity comes over their faces. ‘This guy doesn’t know the dangers of soy, and might get cancer, or worse … man boobs,’ they’re thinking. Just about every fitness expert I read — people I respect and trust — says that soy is bad for you, from Tim Ferriss to the primal/paleo folk. I absolutely respect most of these guys and otherwise think their work on fitness-related matters is great. And yet, when I look for their sources on soy, often they don’t exist, and when they do, I can always trace them back to one place. The Weston A. Price Foundation.

Um, suuuure. So the whole thing is basically setting up a straw man - "only teh evil WAPF sayz soy is baad! WAPF is teh stupid, here are some blag posts from some vegan blogs that sayz they are teh wrong!"

Unfortunately it is true that some WAPF article are pretty questionable. There is an element of woo I can't get behind as a scientist. But there are also articles with scientific references and it would be useful to follow those. But nope, instead the idiot just cites some forum posts and vegan websites.

As for only WAPF having a vendetta, I sincerely doubt Dr. Staffan Lindeberg and Dr. Loren Cordain are associated with WAPF. Maybe you don't know about that because then you might have to go to the library and check out Food and Western Disease instead of Googling crap like the quasi-content farmer you are.

This book has multiple sections about soy.

Soya products cannot be recommended, particularly not for women being treated for breast cancer with tamoxifen, since the tumour-inhibiting effect seems to be counteracted by genistein447,846,852. Genistein, the dominant phytoestrogen in soya bean, potentially stimulates the growth of oestrogen-dependent breast cancers by acting as a so-called promoter that accelerates the progress of existing breast cancer42,321,1464,1622,1803. The idea that soya consumption would explain the relatively low risk of breast cancer in women living in Japan is open for debate730. There are all sorts of reasons why breast cancer could have been less common in Japan than in Europe and North America. On these grounds, the former enthusiasm for soya has lately turned into caution447,1445.

See these little numbers? Those are called references. Real references. Let's compare these references to some references you think are just dandy.

3. FALSE: Soy causes (insert scare claim here: Alzheimer’s, birth defects, etc.). There isn’t any evidence for any of the scare claims that originate from WAPF. I’m not going to argue them all, but I urge you to read these articles from John Robbins, Dr. Neil Barnard, Syd Baumel, and Dr. Joel Fuhrman — they contain many more sources than I could list here, and they’re based on actual evidence.

ACTUAL EVIDENCE? OMG. I am so excited to find out about this actual evidence you speak of.

Do primitive peoples really live longer? No. For example, Innuit Greenlanders, who historically have had limited access to fruits and vegetables, have the worst longevity statistics in North America. Research from the past and present shows that they die on average about 10 years younger and have a higher rate of cancer that the overall Canadian population. 1 Similar statistics are available for the high meat-consuming Maasai in Kenya. They eat a diet high in wild hunted meats and have the worst life expectancy in the modern world. Life expectancy is 45 years for women and 42 years for men. African researchers report that historically Maasai rarely lived beyond age 60. Adult mortality figures on the Kenyan Maasai show that they have a 50% chance of dying before the age of 59.2 We now know that greatly increasing the consumption of vegetables, legumes, fruits, and raw nuts and seeds (and greatly decreasing the consumption of animal products) offers profound increased longevity potential, due in large part to the broad symphony of life-extending phytochemical nutrients that a vegetable-based diet contains. By taking advantage of the year-round availability of high-quality plant foods, we have a unique opportunity to live both healthier and longer than ever before in human history. 1. Iburg KM, Brennum-Hansen H, Bjerregaard P. Health expectancy in Greenland. Scan J Public Health 2001;29(1):5-12 2. http://www.kenya.za.net/maasai-cycles-of-life.html, http://www.who.int/countries/ken/en/

So a defunct website and an article about a modern population in Greenland (I imagine the people of Greenland would be seriously unhappy to be called a "primitive people" since they live a modern lifestyle including books, computers, guns, and modern food and drink and it's just racist to cite the entire country of Kenya when debunking health claims about "primitive people" 0_o ). It's also quite hilarious that Zen Habits cites Dr. Andrew Weil, a potent woo meister himself.

What about the refs in Food and Western Disease?

Duffy, C., Perez, K.&Partridge, A. (2007) Implications of phytoestrogen intake for breast cancer. CA Cancer J Clin 57, 260–77. Power, K.A. & Thompson, L.U. (2007) Can the combination of flaxseed and its lignans with soy and its isoflavones reduce the growth stimulatory effect of soy and its isoflavones on established breast cancer? Mol Nutr Food Res 51, 845–56.

Hmm, these seem different. They almost seem real, as in really relevant and really from real sources or something.

As mentioned earlier, one of the more obvious problems with a vegetarian diet is the development of iron deficiency, which often affects vegetarians, in particular vegans. A high intake of grains and beans contribute to this condition to a considerable degree488,590,669. Soya beans also contain other substances that impede iron absorption besides phytates1099.

Enzymatic digestion of the same proteins in the gut should also be supported through a low intake of protease inhibitors from cereals and beans, including soya products. Finally, the intake of plant lectins from grains and beans should be minimised in an attempt to limit the permeability of the intestines and the blood–brain barrier, and prevent potentially damaging proteins and peptides (food-derived or coming from other sources) from entering the body.

Rats who are fed soya beans after weaning have limited growth, partly due to the effect of lectins.

These apprehensions certainly apply to soya beans. Two experts on health effects of soya beans at the US Food and Drug Administration (FDA), Doergeand Sheehan, the former chief of the Oestrogen Base Program, wrote in 1999 a public letter in protest of the FDA’s approval of health claims for soya products (http://www.dcnutrition.com/news/Detail.CFM?RecordNumber=546). The researchers were concerned about the results of animal experiments where flavonoids in soya (genistein and daidzein) were found to have toxic effects on oestrogen-sensitive tissues and on the pancreas431. Particular caution is needed for children and adolescents children, but this has not prevented the large-scale development and marketing of soya-based infant formulas. Consumption of soya products during pregnancy has been suggested to increase the risk of abnormal development in the nerve system and reproductive organs of the offspring. It has been shown that realistic doses of genistein cause atrophy of the thymus in mice1983. Ishizuki et al. reported goitre and elevated individual thyroid-stimulating hormone levels, although still within the normal range, in 37 healthy iodine-sufficient adults without known thyroid disease, who were fed 30 g of pickled soya beans per day for as little as 1 month431. One study found genistein to disrupt female reproductive function in mice, but the effect in humans has not been examined27.

On the other hand, it has also been suggested that flavonoids in soya beans have beneficial effects, including inhibiting the growth of cancer, but none of these effects have been proven convincingly629. With regard to breast cancer prevention, soya can no longer be recommended, as discussed in Section 4.11.

In old Chinese cuisine, soya products were eaten with caution, and the intake of genistein, e.g., is thought to have been well below the intake of ‘health conscious’ Westerners369.

Whether or not the WAPF is biased, there is a whole lot of bias in the soy industry and a whole lot of funding for people to find uses for soy. When I was an undergrad I participated in soy board research and the food sci department received quite generous stipends for this. I've written about some negative effects of soy and the "soy cartel" in a previous post.

I eat soy sauce and I confess I sometimes indulge in Korean tofu stew (simmered in stock), I just don't use soy as a staple food because I've seen the science and the science says "caution."

And more caution about geting dietary advice from a blog about "zen habits." A hint for future writers from that blog: You can't find studies about why soy might be bad by searching "soy bad." You have to know something about biology and what to look for.

Selected refs, since I'm not spending my entire night copying them. 

447. Duffy, C., Perez, K.&Partridge, A. (2007) Implications of phytoestrogen intake for breast cancer. CA Cancer J Clin 57, 260–77.

1445. Power, K.A. & Thompson, L.U. (2007) Can the combination of flaxseed and its lignans with soy and its isoflavones reduce the growth stimulatory effect of soy and its isoflavones on established breast cancer? Mol Nutr Food Res 51, 845–56.

846 . Jones, J.L., Daley, B.J., Enderson, B.L., Zhou, J.R. & Karlstad, M.D. (2002) Genistein inhibits tamoxifen effects on cell proliferation and cell cycle arrest in T47D breast cancer
cells. Am Surg 68, 575–7; discussion 577–8.

852. Ju, Y.H., Doerge, D.R., Allred, K.F., Allred, C.D.&Helferich, W.G. (2002) Dietary genistein negates the inhibitory effect of tamoxifen on growth of estrogen-dependent human breast cancer (MCF-7) cells implanted in athymic mice. Cancer Res 62, 2474–7.

42. Allred, C.D., Allred, K.F., Ju, Y.H., Virant, S.M. & Helferich, W.G. (2001) Soy diets containing varying amounts of genistein stimulate growth of estrogen-dependent (MCF-7) tumors in a dose-dependent manner. Cancer Res 61, 5045–50.

1464. Qin, L.Q., Xu, J.Y., Tezuka, H., Wang, P.Y. & Hoshi, K. (2007) Commercial soy milk enhances the development of 7,12-dimethylbenz(a)anthracene-induced mammary tumors in rats. In Vivo 21, 667–71.

1622. Seo, H.S., DeNardo, D.G., Jacquot, Y., et al. (2006) Stimulatory effect of genistein and apigenin on the growth of breast cancer cells correlates with their ability to activate ER
alpha. Breast Cancer Res Treat 99, 121–34.

1803. Tonetti, D.A., Zhang, Y., Zhao, H., Lim, S.B. & Constantinou, A.I. (2007) The effect of the phytoestrogens genistein, daidzein, and equol on the growth of tamoxifen-resistant T47D/PKC alpha. Nutr Cancer 58, 222–9.

730. Hirose, K., Takezaki, T., Hamajima, N., Miura, S. & Tajima, K. (2003) Dietary factors protective against breast cancer in Japanese premenopausal and postmenopausal women. Int J Cancer 107, 276–82.

488. Ellis, R., Kelsay, J.L., Reynolds, R.D., et al. (1987) Phytate:zinc and phytate X calcium:zinc millimolar ratios in self-selected diets of Americans, Asian Indians, and Nepalese. J Am Diet Assoc 87, 1043–7.

590. Gibson, R.S. (1994) Content and bioavailability of trace elements in vegetarian diets. Am J Clin Nutr 59 (5 Suppl), 1223S–32S.

669. Harland, B.F., Smith, S.A., Howard, M.P., Ellis, R. & Smith, J.J. (1988) Nutritional status and phytate:zinc and phytate × calcium:zinc dietary molar ratios of lacto-ovo vegetarian Trappist monks: 10 years later. J Am Diet Assoc 88, 1562–6.

1099. Lynch, S.R., Dassenko, S.A., Cook, J.D., Juillerat, M.A. & Hurrell, R.F. (1994) Inhibitory effect of a soybean-protein-related moiety on iron absorption in humans. Am J Clin Nutr
60, 567–72.

431. Doerge, D.R. & Sheehan, D.M. (2002) Goitrogenic and estrogenic activity of soy isoflavones. Environ Health Perspect 110 (Suppl 3), 349–53.

1983. Yellayi, S., Naaz, A., Szewczykowski, M.A., et al. (2002) The phytoestrogen genistein induces thymic and immune changes: a human health concern? Proc Natl Acad Sci USA 99, 7616–21.

27. Akbas, G.E., Fei, X. & Taylor, H.S. (2007) Regulation of HOXA10 expression by phytoestrogens. Am J Physiol Endocrinol Metab 292, E435–42.