Gut microbiota modulation with long-chain corn bran arabinoxylan in adults with overweight and obesity is linked to an individualized temporal increase in fecal propionate

Abstract

Background: Variability in the health effects of dietary fiber might arise from inter-individual differences in the gut microbiota's ability to ferment these substrates into beneficial metabolites. Our understanding of what drives this individuality is vastly incomplete and will require an ecological perspective as microbiomes function as complex interconnected communities. Here, we performed a parallel two-arm, exploratory randomized controlled trial in 31 adults with overweight and class-I obesity to characterize the effects of long-chain, complex arabinoxylan (n = 15) at high supplementation doses (female: 25 g/day; male: 35 g/day) on gut microbiota composition and short-chain fatty acid production as compared to microcrystalline cellulose (n = 16, non-fermentable control), and integrated the findings using an ecological framework. Results: Arabinoxylan resulted in a global shift in fecal bacterial community composition, reduced α-diversity, and the promotion of specific taxa, including operational taxonomic units related to Bifidobacterium longum, Blautia obeum, and Prevotella copri. Arabinoxylan further increased fecal propionate concentrations (p = 0.012, Friedman's test), an effect that showed two distinct groupings of temporal responses in participants. The two groups showed differences in compositional shifts of the microbiota (p ≤ 0.025, PERMANOVA), and multiple linear regression (MLR) analyses revealed that the propionate response was predictable through shifts and, to a lesser degree, baseline composition of the microbiota. Principal components (PCs) derived from community data were better predictors in

Microbial enterotypes beyond genus level: Bacteroides species as a predictive biomarker for weight change upon controlled intervention with arabinoxylan oligosaccharides in overweight subjects

“…Besides body weight, we found indications of B. cellulosilyticus would affect host metabolism, as changes in total serum cholesterol levels could be associated to some extent with this Bacteroides species. Differential Bifidobacterium abundances at the end-point between high and low P/B groups may be explained by competition for substrate between Prevotella and Bifidobacterium spp., 21 as they are consistently found to be inversely correlated across different populations. 22 However, we do not discard some indirect role of these species in microbiota-mediated body weight change as well, being feasible since cross-feeding interactions where Bifidobacterium species take part are well known.…”

Efficacy of metformin and fermentable fiber combination therapy in adolescents with severe obesity and insulin resistance: study protocol for a double-blind randomized controlled trial

“…In human trials involving fermentable fibers, a high degree of between-study heterogeneity has been reported in the clinical response to fiber [ 84 , 85 ]. These inconsistencies might stem from the extensive interindividual differences in gut microbial configurations at baseline and in response to dietary fiber supplementation [ 48 , 84 , 86 ]. This concept is highlighted by the recent work of Hjorth and colleagues, where individuals with a higher Prevotella -to- Bacteroides ratio at baseline lost significantly more body weight and body fat on a fiber-rich diet than individuals with a lower ratio [ 87 ].…”

“…Alternatively, participants will be allowed to mix the fiber, or placebo, with foods (e.g., added to cereals, soups, and yogurt), if preferred, to allow flexibility and maximize compliance, which is important due to the duration of the intervention. The fiber placebo will consist of MCC, a non-fermentable fiber with no effect on the gut microbiota [ 48 ].…”

Not All Fibers Are Born Equal; Variable Response to Dietary Fiber Subtypes in IBD

“…AX is a large component of dietary fiber found in cereal grains and other plant and animal food sources ( 115 – 117 ). The fermentation of AX by gut microbes such as Streptococcus and Bifidobacteria results in the production of SCFAs, including acetate, propionate, and butyrate ( 115 , 118 – 121 ). Furthermore, downstream fungal microbes, such as Saccharomyces cerevisiae result in fermentation processes producing biomass and ethanol ( 122 ).…”

“…It is important to note that the evidence in support of this includes very limited numbers of human studies, and a number of contradictory animal and in vitro studies, however, these recommendations may help certain individuals. Interindividual variability in microbial composition and function will also need to be considered, as further discussed below ( 118 ).…”