Dietary intake of folate, vitamin B6, vitamin B12, and riboflavin and the risk of incident dementia

Background/Objectives: Low intake of B-vitamins may increase dementia; However, epidemiological evidence, particularly for riboflavin (vitamin B₂), remains sparse. The aim of this study was to examine the association between dietary intakes of B-vitamins (riboflavin, vitamin B ₆ , vitamin B ₁₂ , and folate) and the incidence of disabling dementia necessitating care under the Japan’s national insurance over a 15-year observation period. Methods: As part of the Circulatory Risk in Communities Study, a prospective study involving a community-based cohort of 4,171 Japanese individuals aged 40 to 69 years was conducted. Dietary intakes of B-vitamins were estimated through a single 24-hour dietary recall method. Hazard ratios and 95% confidence intervals of disabling dementia were estimated using area-stratified Cox proportional hazard models. Results: Over a median follow-up of 15.4 years, 887 cases of disabling dementia were identified. Riboflavin intake was inversely associated with risk of disabling dementia among men and women; comparing the highest and lowest quartiles, multivariable hazard ratios and 95% CIs were 0.55 (95% CI 0.39–0.78; P for trend < 0.001) in men and 0.51 (0.39–0.68; P for trend < 0.001) in women. A similar inverse association was observed for vitamin B ₁₂ intake among men, and folate intake among women, with multivariable hazard ratios and 95% CIs of 0.69 (0.49–0.98; P for trend = 0.04) and 0.66 (0.49–0.88; P for trend = 0.0008), respectively. Conclusions: Our findings suggest that dietary intake of B-vitamins, especially riboflavin, is associated with a reduced risk of disabling dementia in Japanese individuals.