Gillian N.F. Larik1, Emanuel E. Canfora1, Evert M. van Schothorst2, Blaak E. Ellen1
1Department of Human Biology, Maastricht University, The Netherlands 2Human and Animal Physiology, Wageningen University, The Netherlands
g.larik@maastrichtuniversity.nl
Introduction: Our understanding of the diet–gut microbiota–host metabolism axis remains limited due to the lack of real-time measures of microbial fermentation. To address this, we developed a novel, non-invasive system for continuous measurements of Saccharolytic (dietary fiber-derived) fermentation gases (H2 and CH4) and metabolic kinetics (O2 and (13)CO2) in humans. Using this fermentation chamber, we investigated the effects of a two-day dietary fiber mixture (inulin + resistant starch) on fermentation dynamics in lean normoglycemic individuals and in individuals with overweight/obesity.
Method: This randomised, placebo-controlled, crossover study included 12 lean normoglycemic individuals and 13 individuals with overweight/obesity with prediabetes/IR. Participants received either a 21-gram fiber mixture (inulin + resistant starch) or an isocaloric control (maltodextrin) for two days. In the evening, after the start of the supplementation, participants entered the chamber for 36h. The next morning a 13C-labeled fiber (inulin) was provided. Changes in fermentation gas pattern excretion rates were assessed (primary outcome) alongside other metabolic parameters, including energy expenditure and substrate oxidation.
Results: Fiber supplementation increased 24h H2 (Δlean 485ml ± 506 and Δindividuals with prediabetes/IR 415ml ± 545, P < 0.05) and 13CO2 release in both groups (Δlean 56927 ± 13883 δ13CO2-CO2 and Δindividuals with prediabetes/IR 44927 ± 11546 δ13CO2-CO2, P < 0.05). Interestingly, 24h expired 13CO2 was increased more in lean individuals after fiber supplementation versus placebo compared to individuals with IR/prediabetes (general linear model, phenotype effect P < 0.05). Fiber supplementation overall reduced plasma insulin concentrations and increased plasma propionate, butyrate and hexanoate concentrations in lean individuals (P < 0.05). No significant changes in plasma insulin or microbial metabolites were observed in individuals with IR/prediabetes. Analyses of other metabolic parameters, will be available during the meeting.
Conclusion: Our novel methodology revealed that a two-day fiber supplementation greatly impacts gut microbial gas profiles as an indicator of saccharolytic fermentation. Moreover, lean individuals and individuals with prediabetes/IR showed distinct fermentation profiles.