Abstract
Objectives
Dietary fiber consumption improves cardiometabolic health, partly by enhancing microbial diversity and increasing production of butyrate in the distal gut. However, it is unclear whether the benefits associated with different types of fiber vary based on the gut microbiota composition. We surveyed nine different human gut microbial communities by characterizing them in germ-free mice and selected two communities based on their butyrate-producing capacity (“B”) and diversity (“D”) (i.e., high- vs. low-BD communities). Our objective was to assess the role of high- vs. low-BD communities on the metabolic effects elicited by the consumption of various dietary fibers.
Methods
We formulated seven diets with different sources of dietary fiber (10% wt/wt): i) resistant starch type 2 (RS2); ii) RS4; iii) inulin; iv) short-chain fructooligosaccharides (scFOS); v) pectin, vi) assorted fiber (a combination of the 5 fermentable fibers), and vii) cellulose (a non-fermentable control). Germ-free C57BL/6 male mice were colonized with either the high- or low-BD communities and fed the assorted fiber diet for 2 weeks to reach stability of microbial engraftment. Mice were then switched to one of the 7 diets for 4 weeks (n = 7–10/group; 117 mice total). We quantified cecal level of short-chain fatty acids and assessed the gut microbiota composition using 16S rRNA gene-based sequencing.
Results
Mice colonized with the high-BD community have lower body weight and fat mass compared to the low-BD community when fermentable-fiber sources RS2, inulin, or assorted fiber were present in the diet. Body weight did not differ between the two communities when mice were fed RS4, scFOS, pectin, or cellulose diets. Lower body weight and fat mass were associated with greater cecal butyrate concentrations and microbial diversity.
Conclusions
The efficacy of dietary fiber interventions on metabolic health varies based on the gut microbiota composition. Overall, our results suggest that dietary fiber supplementations need to be matched with the metabolic potential of the gut microbiome.
Funding Sources
Fondation Leducq, USDA, and NIH.
Effects of dietary fibre source on microbiota composition in the large intestine of suckling piglets
