March 11, 2009 – The more menopausal – or postmenopausal – women consume soy products, the less likely they are to suffer from colorectal cancer. This is what the results of an American study indicate1 conducted using data collected from 68,412 healthy women in the Shanghai region of China, followed for about six years.
The researchers assessed each participant’s usual soy intake and then noted any cases of colon or rectal cancer that appeared during the study. According to the results, women who consumed the most soy products saw their risk of developing colorectal cancer reduced by about 30% compared to those who consumed the least.
In fact, each increase of 5 g of soy per day (dry weight equivalent regardless of source) has been estimated to result in an 8% reduction in risk. The results were more convincing in postmenopausal women. This stronger protective effect could be attributed to soy isoflavones, the researchers believe.
The soy products considered for this study consisted primarily of unfermented products (soy beverage, soybean, and tofu). In addition to isoflavones, these products are rich in soy protein, fiber, calcium and folic acid, all nutrients that may contribute to the observed protective effect.
None of the participants took any supplements in the form of protein extracts or phytoestrogens (isoflavones). So it is difficult to determine with precision whether the observed protective effect is attributable to only one of the substances contained in soy or to a combination of several of them.
The Canadian Cancer Society estimates that an average of 413 Canadians learn each week that they have colorectal cancer. It is the second leading cause of cancer death.
Pierre Lefrançois – PasseportSanté.net
1. Yang G, Shu XO, Li H et al. Prospective cohort study of soy food intake and colorectal cancer risk in women, Am J Clin Nutr. 2009 Feb; 89 (2): 577-83. To consult the full version of the study: www.pubmedcentral.nih.gov [consulté le 11 mars 2009].
