Abstract Body (Do not enter title and authors here): Background
Dietary fiber intake has been associated with a lower risk of type 2 diabetes (T2D). However, the association between fiber from various food sources and T2D risk remains underexplored, and the mechanisms involved are not yet well understood.
Methods
We followed 155,633 women and 42,528 men from three large prospective US cohorts for up to 34 years. Dietary fiber intake was estimated using validated food-frequency questionnaires. Cox proportional hazards models were used to evaluate the association between fiber intake and T2D risk. We examined the association between fiber intake, ten plasma metabolic biomarkers, and a metabolomic score indicative of T2D risk. Additionally, we assessed the association between fiber intake, the gut microbiome, and the T2D metabolomic score.
Results
During follow-up, we documented 18,681 incident T2D cases. A higher intake of total fiber (HR comparing extreme quintiles=0.89; 95% CI: 0.84, 0.95), cereal fiber (HR=0.77; 95% CI: 0.73, 0.82), and fruit fiber (HR=0.88; 95% CI: 0.83, 0.93) was associated with a lower T2D risk (all P-trend≤0.004). In contrast, fiber from vegetables, particularly starchy vegetables (peas, yams/sweet potatoes, and corn) and onions, was associated with a moderately increased risk of T2D. Total fiber, cereal fiber, and fruit fiber were associated with more favorable profiles of plasma insulinemic, lipid, and inflammatory biomarkers, and a metabolomic profile indicative of a lower T2D risk. We also identified multiple gut microbial species, such as Faecalibacterium prausnitzii, Ruminococcus lactaris, and Gemmiger formicilis, along with relevant butyric acid-producing enzymes, all of which were associated with fruit fiber intake and may play a role in the relationship between fiber intake and T2D.
Conclusion
A higher intake of total, cereal, and fruit fiber is associated with a reduced risk of T2D and more favorable metabolic profiles, with the gut microbiome potentially contributing to the beneficial association of fruit fiber.