TOKYO—Researchers found no benefits of soy products or isoflavone intake with respect to risk of type 2 diabetes in either men or women in a recent Japanese study (J Nutr. 2010;140(3):580-586). A total of 25,872 men and 33,919 women, aged 45 to 75 years, participated in the second survey of the Japan Public Health Center-Based Prospective Study and had no history of diabetes. Soy product and isoflavone intakes were ascertained using a 147-item FFQ. A total of 1,114 new cases of type 2 diabetes were self-reported.
Intakes of soy products and isoflavones were not significantly associated with type 2 diabetes in either men or all women. However, among overweight women (BMI 25 kg/m2), a higher intake of soy products was associated with a lower risk of type 2 diabetes; multivariable-adjusted odds ratios for the lowest through highest quintiles of soy product intake were 1.00 (reference), 0.78 (0.52–1.18), 0.79 (0.52–1.20), 0.62 (0.39–0.99) and 0.89 (0.55–1.44), respectively, and a similar risk pattern for daidzein and genistein intakes were found. Researchers said the possible protective association of soy and isoflavone intakes among overweight women deserves further investigation.