Abstract
Wheat dextrin soluble fibre may have metabolic and health benefits, potentially acting via mechanisms governed by the selective modulation of the human gut microbiota. Our aim was to examine the impact of wheat dextrin on the composition and metabolic activity of the gut microbiota. We used a validated in vitro three-stage continuous culture human colonic model (gut model) system comprised of vessels simulating anatomical regions of the human colon. To mimic human ingestion, 7 g of wheat dextrin (NUTRIOSE® FB06) was administered to three gut models, twice daily at 10.00 and 15.00, for a total of 18 days. Samples were collected and analysed for microbial composition and organic acid concentrations by 16S rRNA-based fluorescence in situ hybridisation and gas chromatography approaches, respectively. Wheat dextrin mediated a significant increase in total bacteria in vessels simulating the transverse and distal colon, and a significant increase in key butyrate-producing bacteria Clostridium cluster XIVa and Roseburia genus in all vessels of the gut model. The production of principal short-chain fatty acids, acetate, propionate and butyrate, which have been purported to have protective, trophic and metabolic host benefits, were increased. Specifically, wheat dextrin fermentation had a significant butyrogenic effect in all vessels of the gut model and significantly increased production of acetate (vessels 2 and 3) and propionate (vessel 3), simulating the transverse and distal regions of the human colon, respectively. In conclusion, wheat dextrin NUTRIOSE® FB06 is selectively fermented in vitro by Clostridium cluster XIVa and Roseburia genus and beneficially alters the metabolic profile of the human gut microbiota.
Highlights
The increasing worldwide prevalence of obese and overweight individuals is a major public health concern [1]
Following administration of wheat dextrin (WD), total bacterial populations significantly increased by 0.37 log10 in V2 simulating the transverse colon (P < 0.0001) and 0.30 log10 in V3 simulating the distal colon (P < 0.001)
Concentrations of Clostridium coccoides – Eubacterium rectale significantly increased by 0.71 log10 in V1 (P < 0.0001), 0.67 log10 in V2 (P < 0.0001) and 0.37 log10 in V3 (P < 0.01)
Summary
The increasing worldwide prevalence of obese and overweight individuals is a major public health concern [1]. The accretion of excess adipose tissue, is associated with elevated chronic systemic low-grade inflammation and increased risk of metabolic diseases, such as type 2 diabetes and cardiovascular disease (CVD) [2]. The pathogenesis of these conditions is attributable to a complex interaction between genetic, metabolic, environmental and behavioural factors, the specific contribution of each of these determinants is not fully understood [3]. A recent rodent model study by Liou et al, has provided the first empirical evidence that changes in the gut microbiota may contribute towards reduced host weight and adiposity [18]
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