Dietary intake of beans and risk of disabling dementia: The Circulatory Risk in Communities Study (CIRCS)

Objective To examine whether bean intake (including soybeans) among Japanese adults is associated with risk of disabling dementia severe enough to require care under the national insurance system. Methods This cohort study involved 3739 individuals aged 40 to 64 years. The participants were categorized into five groups based on their dietary bean intake estimated by a 24h dietary recall. Hazard ratios and 95% confidence intervals of disabling dementia were estimated using Cox proportional hazard models adjusted for potential confounding factors (smoking, drinking, and intakes of energy and fish). Results During the 59,681 person-year follow-up, 670 cases of disabling dementia were observed. A weak inverse association between bean intake and risk of disabling dementia was found; the multivariable hazard ratios (95% CIs) were 0.79 (0.62-1.00), 0.80 (0.63-1.01), 0.84 (0.67-1.06), and 0.78 (0.62-0.99) for the four groups with higher bean intake, respectively, compared with the lowest group (P for trend = 0.21). A significant inverse association was observed for dementia without a history of stroke; for the four groups with higher bean intake the multivariable hazard ratios were 0.81 (0.61-1.08), 0.70 (0.52-0.95), 0.71 (0.52-0.95), and 0.69 (0.51-0.92), respectively, (P for trend = 0.03). No such association was observed for dementia with history of stroke. The group with increased natto intake were inversely associated with risk of disabling dementia (P for trend = 0.003), but tofu intake was not (P for trend = 0.19). Conclusions Bean intake was inversely associated with risk of disabling dementia in those without a history of stroke.