Guided dietary fibre intake as a means of directing short-chain fatty acid production by the gut microbiota

The human colon contains a complex microbial community (the microbiota), composed mostly of bacteria, that degrades and ferments indigestible polysaccharides known collectively as dietary fibre. Acting as a co-operative society and using specialised biochemical mechanisms, the microbiota processes the dietary fibre and produces short-chain (volatile) fatty acids (SCFAs) as fermentation products. Mucosal and immune cell receptors and signalling molecules important in maintaining gut homeostasis respond to the presence of these bacterial metabolites. This article provides a perspective on the potential use of dietary fibre to modulate the functioning of the microbiota and hence stimulate health-supporting processes in guided food interventions. Major problems to be solved in developing this approach include the lack of detailed knowledge of the assemblage and functioning of bacterial consortia in the gut microbiota, the relatively large quantity of dietary fibre that might be needed to produce consistent outcomes in humans, the possibility that bacterial species that could utilise more exotic dietary fibres present in ancestral foods may be missing from Western microbiotas, the variation in response to dietary modification because high diversity microbiotas are resistant to change, and the need to develop new forms of dietary fibre supplements that are palatable and tolerable when ingested in efficacious amounts.