Dietary fiber intake and type 2 diabetes in Japanese men and women: the Japan Public Health Center-based Prospective Study.

Background: Total dietary fiber and cereal fiber intake have been reported to be associated with decreased risk of type 2 diabetes. However, evidence from Asia is limited and inconsistent. In addition, no Japanese study has examined the association of dietary fiber intake from food sources.

Objective: We prospectively examined the association of dietary fiber and its source with type 2 diabetes risk among Japanese adults.

Methods: Participants were 27,798 men and 36,883 women aged 44-76 who completed a food frequency questionnaire in 1995-1998 (baseline of the present study), had no history of diabetes, and returned a follow-up questionnaire five years later, when physician-diagnosed type 2 diabetes was self-reported. Odds ratios of the newly diagnosed type 2 diabetes according to dietary fiber intake were estimated by logistic regression.

Results: During the 5-year period, 1190 cases of newly diagnosed type 2 diabetes were identified. Total dietary fiber intake was not significantly associated with type 2 diabetes; the multivariable-adjusted odds ratio of type 2 diabetes for the highest versus lowest quartile of total dietary fiber intake was 0.91 (95% confidence interval 0.72-1.15) (P for trend = 0.36). On analysis by food source, dietary fiber intake from any of cereals, legumes, vegetables, and fruits was not associated with type 2 diabetes, with corresponding values (95% confidence intervals) of 0.95 (0.79-1.14) for cereals, 0.96 (0.78-1.19) for legumes, 1.00 (0.81-1.23) for vegetables, and 1.12 (0.90-1.39) for fruits.

Conclusions: Our findings suggest that dietary fiber intake has no association with the risk of type 2 diabetes among Japanese.