Dietary Folate, Vitamin B6 and Vitamin B12 and Risk of Cardiovascular Diseases among Individuals with Type 2 Diabetes: a Case-Control Study

Background: Emerging evidence suggests that dietary one-carbon metabolism-related B-vitamins are associated with the reduced risk of cardiovascular disease (CVD) in general populations. However, only a few studies have assessed their associations in patients with type 2 diabetes (T2D). Objective: This study aims to assess the associations between the intake of three one-carbon metabolism-related B-vitamins (folate, vitamin B6 and vitamin B12) and CVD risk in Chinese patients with T2D. Methods: A hospital-based case–control study of 419 patients with T2D and newly diagnosed CVD and 419 age- (±5 years) and sex-matched T2D-only controls was carried out in China. A validated 79-item semiquantitative food-frequency questionnaire administered in face-to-face interviews was used to measure dietary B-vitamin intake. Conditional logistic regression was used to assess associations, which were tested by estimating odds ratios (ORs) with 95% confidence intervals (CIs). Results: Compared with the lowest quartile, the multivariable-adjusted ORs and 95% CIs for highest quartile were 0.32 (95% CI 0.20, 0.52; P-trend < 0.001) for folate, 0.47 (95% CI 0.30, 0.76; P-trend = 0.002) for vitamin B6 and 1.02 (95% CI 0.67, 1.55; P-trend = 0.841) for vitamin B12. Consistent inverse associations were found for folate intake from eggs, vegetables, fruits, soy and other foods but not for folate intake from grains. Conclusions: Findings suggest that the high consumption of folate and vitamin B6, but not that of vitamin B12, might be associated with the low risk of CVD in patients with T2D. This study suggests that dietary folate and vitamin B6 protect against CVD in patients with T2D.