Just How Much Soy Did Asians Eat?
In short, not that much, and contrary to what the industry may claim soy has never been a staple in Asia. A study of the history of soy use in Asia shows that the poor used it during times of extreme food shortage, and only then the soybeans were carefully prepared (e.g. by lengthy fermentation) to destroy the soy toxins. Yes, the Asians understood soy all right!
Many vegetarians in the USA, and Europe and Australia would think nothing of consuming 8 ounces (about 220 grams) of tofu and a couple of glasses of soy milk per day, two or three times a week. But this is well in excess of what Asians typically consume; they generally use small portions of soy to complement their meal. It should also be noted that soy is not the main source of dietary protein and that a regime of calcium-set tofu and soymilk bears little resemblance to the soy consumed traditionally in Asia.
Perhaps the best survey of what types/quantities of soy eaten in Asia comes from data from a validated, semi quantitative food frequency questionnaire that surveyed 1242 men and 3596 women who participated in an annual health check-up program in Takayama City, Japan. This survey identified that the soy products consumed were tofu (plain, fried, deep-fried, or dried), miso, fermented soybeans, soymilk, and boiled soybeans. The estimated amount of soy protein consumed from these sources was 8.00 ± 4.95 g/day for men and 6.88 ± 4.06 g/day for women (Nagata C, Takatsuka N, Kurisu Y, Shimizu H; J Nutr 1998, 128:209-13).
According to KC Chang, editor of Food in Chinese Culture, the total caloric intake due to soy in the Chinese diet in the 1930's was only 1.5%, compared with 65% for pork. For more information on the traditional use of soy products, contact the Price Pottenger Nutrition Foundation.
The chief concern we have about the consumption of large amounts of soy is that there is a risk of mega-dosing on isoflavones. If soy consumers follow the advice of Protein Technologies International (manufacturers of isolated soy protein) and consume 100 grams of soy protein per day, their daily genistein intake could easily exceed 200 milligrams per day. This level of genistein intake should definitely be avoided. For comparison, it should be noted that Japanese males consume, on average, less than 10 milligrams of genistein per day (Fukutake M, Takahashi M, Ishida K, Kawamura H, Sugimura T, Wakabayashi K; Food Chem Toxicol 1996, 34:457-61).
What about the traditional use of soy in infant feeding?
Ever heard the industry line that 'soy formulas must be safe because Asian infants have been eating soy for centuries'? Just another piece of false advertising, a little like the claims that 'soy formulas are better than breast milk' that many parents that have fed soy formulas testify to. And to set the record straight, soy was seldom used in infant feeding in Asia.
Ernest Tso is credited with the development of the first soymilk diet that was able to sustain an infant for the first eight months of life. Writing in the Chinese Journal of Physiology in 1928, Tso noted that soybean milk is a native food used in certain parts of the country as a morning beverage but it is little used as part of the diet for children. Its nutritive properties as a food for young infants are practically unknown.
Eight years later, Tso's comments were still valid. Writing in the 1930's, Dr RA Guy of the Department of Public Health of the Peiping Union Medical College found it 'pertinent to note that we have never found soybean milk naturally used by Peiping women to feed their children. This beverage is not made in the home in Peiping, but is sold by street vendors, as a hot, very weak solution of soybean protein and is usually drunk by old people in place of tea. The milk, as reinforced for the feeding of young infants, is rather tedious and difficult to prepare. As dispensed recently by the various health stations, it is in demand, but is just as artificial in this community as cow's milk' (Guy RA. Chinese Med J. 1936; 50:434-442).
In a later publication, Guy reported on the use of soybean milk as a food for infants. The whole purpose of this report was to comment on the possible use of soymilk to address the problem of feeding those infants without sufficient maternal milk in a country where cow's milk was not native. He again noted that although a weak soy milk or 'tofu chiang' was 'sold hot in Peking by street vendors and was taken by old people in place of tea', that 'contrary to Western notions' it was not usual to feed soy milk to infants (Guy RA and Yeh KS. Chinese Med J. 1938; 54:1-30).
It seems those same Western notions that made Asians out to be greater soy consumers than they were are still prevalent. Why is that? Asia is a huge market for the soy industry and the soy industry efforts to convince Asians that their ancestors ate much more soy than they actually did are purely profit driven. We view the attempts of the soy industry to re-write the history books with the contempt it deserves.