Prebiotic dietary fibre intervention improves fecal markers related to inflammation in obese patients: results from the Food4Gut randomized placebo-controlled trial

Abstract

Purpose: Inulin-type fructans (ITF) are prebiotic dietary fibre (DF) that may confer beneficial health effects, by interacting with the gut microbiota. We have tested the hypothesis that a dietary intervention promoting inulin intake versus placebo influences fecal microbial-derived metabolites and markers related to gut integrity and inflammation in obese patients.

Methods: Microbiota (16S rRNA sequencing), long- and short-chain fatty acids (LCFA, SCFA), bile acids, zonulin, and calprotectin were analyzed in fecal samples obtained from obese patients included in a randomized, placebo-controlled trial. Participants received either 16 g/d native inulin (prebiotic n = 12) versus maltodextrin (placebo n = 12), coupled to dietary advice to consume inulin-rich versus inulin-poor vegetables for 3 months, in addition to dietary caloric restriction.

Results: Both placebo and prebiotic interventions lowered energy and protein intake. A substantial increase in Bifidobacterium was detected after ITF treatment (q = 0.049) supporting our recent data obtained in a larger cohort. Interestingly, fecal calprotectin, a marker of gut inflammation, was reduced upon ITF treatment. Both prebiotic and placebo interventions increased the ratio of tauro-conjugated/free bile acids in feces. Prebiotic treatment did not significantly modify fecal SCFA content but it increased fecal rumenic acid, a conjugated linoleic acid (cis-9, trans-11 CLA) with immunomodulatory properties, that correlated notably to the expansion of Bifidobacterium (p = 0.031; r = 0.052).

Conclusions: Our study demonstrates that ITF-prebiotic intake during 3 months decreases a fecal marker of intestinal inflammation in obese patients. Our data point to a potential contribution of microbial lipid-derived metabolites in gastro-intestinal dysfunction related to obesity. CLINICALTRIALS.

Gov identifier: NCT03852069 (February 22, 2019 retrospectively, registered).

Keywords: Gut microbiota; Microbial metabolites; Obesity; Prebiotic.

Fig. 1

Fecal concentration of zonulin (a) and calprotectin (b) in obese patients receiving prebiotic or placebo for 3 months. Individual values and means are presented (placebo: n = 9; prebiotic: n = 11). Baseline data were analyzed by Mann–Whitney test (p > 0.05). Matched-pairs Wilcoxon signed-rank tests were performed to compare changes from baseline (within-group variations;*p ≤ 0.05). Between-groups variations were analyzed by Mann–Whitney U tests (p > 0.05)

Fig. 2

Fecal SCFA profile (% identified SCFA) in obese patients receiving prebiotic or placebo for 3 months. Values are means (placebo: n = 10; prebiotic: n = 12). Baseline data were analyzed by Mann–Whitney test (p > 0.05). Matched-pairs Wilcoxon signed-rank tests were performed to compare changes from baseline (within-group variations;*p ≤ 0.05). Between-groups variations were analyzed by Mann–Whitney U tests (p > 0.05)

Fig. 3

Heatmap of Spearman’s correlations between significant shift in bacteria due to the intervention and the significant shift in fecal concentrations of biomarkers of gut barrier/inflammation (a) and of the relative proportions of LCFA (b). Orange circles indicate significant negative correlations whereas purple circles represent significant positive correlations (p < 0.05)