Soy Product and Isoflavone Intakes Are Associated with a Lower Risk of Type 2 Diabetes in Overweight Japanese Women

Abstract

Isoflavones have been shown to improve glucose metabolism, but epidemiologic data are limited. We prospectively investigated the relationship between soy product and isoflavone intake and the risk of developing type 2 diabetes among Japanese adults. Participants were 25,872 men and 33,919 women aged 45-75 y, who 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. Odds ratios of self-reported, physician-diagnosed type 2 diabetes over 5 y were estimated using logistic regression analysis. A total of 1114 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 > or = 25 kg/m(2)), a higher intake of soy products was associated with a lower risk of type 2 diabetes; multivariable-adjusted odds ratios (95% CI) 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 we found a similar risk pattern for daidzein and genistein intakes. Overall, our results suggest that there are no benefits of soy product or isoflavone intake with respect to risk of type 2 diabetes in either men or women. The possible protective associations of soy and isoflavone intakes among overweight women deserves further investigation.

Legume consumption and its association with fasting glucose, insulin resistance and type 2 diabetes in the Indian Migration Study

“…The average daily intake of the reference group (Q1) in our study population was 23·5 g/d, which corresponds to high levels in other populations (22,24) ; only two participants consumed 3 g/d, which was classified as 'high' consumption associated with lower glucose intolerance rates in one previous study (22) . Only one published study on legumes showed intake greater than the current study population in the reference group (29 g/d in the lowest quintile), in which the authors also reported no association between legumes (soya) intake and type 2 diabetes in Japanese women (25) . This may partly explain why we observed inverse associations in only the highest tertiles of carbohydrate, protein, fat and sugar consumption, where these participants' legume consumption was significantly higher (P < 0·0001; data not shown) than in the lowest tertiles; we also found higher mean legume intake in persons of lower BMI compared with those of higher BMI (P = 0·02; data not shown).…”

“…T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3 M The epidemiological data focusing on legumes specifically showed inverse associations between legumes and diabetes in some (22)(23)(24)(25)(26)30) but not all (25,(27)(28)(29)31) studies, including one population-based study in India reporting an inverse association between legume intake and selfreported diabetes (30) . The authors were restricted to National Family Health Survey-3 questions on frequency intake without quantitative measures, were unable to control for total energy intake (which is correlated with legume intake) or other confounders, such as physical activity and assessed self-reported diabetes, which may be subject to temporal ambiguity of diabetic patients increasing legume intake as a result of their diagnosis.…”

“…Soluble fibres and the presence of α-glucosidase inhibitors allow for slower absorption and reduction of the dietary glycaemic index. Epidemiological studies in the West have yielded inconsistent associations with legume intake (22)(23)(24)(25)(26)(27)(28)(29) but the average daily intake in grams is much lower than in India, where evidence is also mixed with respect to associations with diabetes and glycaemic index (30,31) . Given the higher levels of legume consumption in traditional Indian diets, trends towards lower consumption patterns over time (32,33) and concomitant quadrupling of diabetes prevalence since the 1970s (expected to touch 100 million people by 2030 (5) ), Indian populations can yield important information on the association between legumes and diabetes-related outcomes.…”

Inverse association between soya food consumption and insulin resistance in Japanese adults

“…The consumption of soya foods (tofu and other soya products) was previously associated with a significantly reduced prevalence of glycosuria in 39 385 Chinese women aged 40-70 years without diabetes, especially postmenopausal women with BMI < 25 kg/m 2 (15) . Nanri et al reported a significant correlation between soya products and daidzein intake and a reduced cumulative incidence of type 2 diabetes among women with BMI > 25 kg/m 2 and postmenopausal women (16) . In a prospective study in China, Villegas et al reported that the consumption of legumes and soya foods was associated with a decreased risk of type 2 diabetes in 64 227 women aged 40-70 years (17) .…”

“…An inverse association between soya food intake and the prevalence of glycosuria was also reported in postmenopausal non-obese Chinese women (15) . Furthermore, a recent prospective study in Japan showed that higher intake of soya products and isoflavones was associated with a decreased odds ratio of diabetes among overweight or postmenopausal women (16) . The consumption of some soya foods was inversely associated with the risk of type 2 diabetes among Asians in two prospective studies (17,18) .…”