Soy food intake and risk of endometrial cancer in Chinese women in Shanghai
It is known that Chinese women have significantly lower rates of endometrial cancer compared with Western women, and lower rates of endometrial cancer may be explained by soy. Endometrial cancer is an increasing problem in Western countries, mainly due to obesity. Obese women have higher levels of natural oestrogen because fat tissue also produces oestrogen. Oestrogen can increase the risk of endometrial cancer. According to a report in the 29 May issue of the British Medical Journal, regular soy consumption reduced the risk of endometrial cancer by 30 to 40 percent in women studied in Shanghai.This protective effect of soy was particularly significant in obese women, who are at high risk of endometrial cancer. Soy foods may be protective because they are rich in isoflavones, which act like oestrogen in the body but are not as potent as natural oestrogen. Isoflavones alter endogenous estrogen concentrations by competitively binding to estrogen receptors, inhibiting key steroid biosynthetic enzymes, increasing steroid clearance from the circulation, and stimulating the production of sex hormone binding globulin.
Professor Shu and her colleagues collected data from 982 Chinese women in Shanghai, aged 30 to 69, who had been diagnosed with endometrial cancer, and compared them with 846 healthy Chinese women. The researchers measured the amount of soy foods eaten over five years and the women's current body weight. In this study, the average intake of soy isoflavones was about 25 times higher than in Western women, while the incidence of endometrial cancer is only one fifth to one third of that in Western countries.
As the number of women in the study was small, further research in a larger population is needed to confirm this finding.
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Wang Hong Xu et al, British Medical Journal 2004 May 29; 328 (7451): 1285