Sex-specific associations of habitual intake of soy protein and isoflavones with risk of type 2 diabetes.

Abstract

A possible mechanism by which intake of soy isoflavones leads to an improvement in glucose metabolism has been suggested. However, epidemiological evidence of a link between dietary soy isoflavone and type 2 diabetes is not convincing. This study aimed to evaluate the prospective associations between intake of dietary soy protein and isoflavones (total isoflavones, daidzein and genistein) and risk of type 2 diabetes in a community-based cohort of Korean adults aged≥40 years, the Korean Multi-Rural Communities Cohort (MRCohort). A total of 8269 participants who did not have type 2 diabetes were enrolled. Dietary intake was calculated using a food frequency questionnaire. Over 50,063 person-years of follow-up, 531 participants developed type 2 diabetes. Significant dose-response inverse associations were observed between dietary soy protein and isoflavones (quartiles) and type 2 diabetes in women (incidence rate ratio, IRR=0.63, 95% CI=0.45-0.87, P for trend=0.0078 for soy protein; IRR=0.62, 95% CI=0.45-0.86, P for trend=0.0031 for total isoflavones for the highest quartile compared with the lowest quartile). Similar significant linear trends were found for both daidzein and genistein. However, there were no significant associations with soy protein and isoflavones in men. The sex-specific differences in associations between soy protein and isoflavones intakes and type 2 diabetes risk were statistically significant (all P for interaction<0.05). Habitual intake of soy protein and isoflavones may be inversely associated with type 2 diabetes in women, but not in men. Dietary soy components may play different roles in the development of type 2 diabetes in men and women.