High cereal fibre but not total fibre is associated with a lower risk of type 2 diabetes: Evidence from the Melbourne Collaborative Cohort Study.

Abstract

To assess the associations of total dietary fibre and fibre from different food sources (ie, cereal, fruit and vegetables) with the risk of diabetes. The Melbourne Collaborative Cohort Study enrolled 41 513 participants aged 40 to 69 years from 1990 to 1994. The first and second follow-ups were conducted in 1994 to 1998 and 2003 to 2007, respectively. Self-reported diabetes incidence was recorded at both follow-ups. We analysed data from 39 185 participants, with a mean follow-up of 13.8 years. The relationships between dietary fibre intake (total, fruit, vegetable and cereal fibre) and the incidence of diabetes were assessed using modified Poisson regression, adjusted for dietary, lifestyle, obesity, socioeconomic and other possible confounders. Fibre intake was categorized into quintiles. At total of 1989 incident cases were identified over both follow-up surveys. Total fibre intake was not associated with diabetes risk. Higher intake of cereal fibre (P for trend = 0.003), but not fruit (P for trend = 0.3) and vegetable fibre (P for trend = 0.5), was protective against diabetes. For cereal fibre, quintile 5 versus quintile 1 showed a 25% reduction in diabetes risk (incidence risk ratio [IRR] 0.75, 95% confidence interval [CI] 0.63-0.88). For fruit fibre, only quintile 2 versus quintile 1 showed a 16% risk reduction (IRR 0.84, 95% CI 0.73-0.96). Adjustment for body mass index (BMI) and waist-to-hip ratio eliminated the association and mediation analysis showed that BMI mediated 36% of the relationship between fibre and diabetes. Intake of cereal fibre and, to a lesser extent, fruit fibre, may reduce the risk of diabetes, while total fibre showed no association. Our data suggest that specific recommendations regarding dietary fibre intake may be needed to prevent diabetes.