Manipulating the kinetics and site of colonic fermentation with different fibre combinations - a review

The effects of dietary fibre on gut microbiota and the colonic markers of health have been well investigated, along with the kinetics of fibre fermentation. Most of the evidence available is based on faecal analysis or static in vitro models of colonic fermentation of constant amounts of fibres incubated individually with faecal inoculum. These results offer a limited understanding of the effects of different fibres on different bacterial species, and changes that occur along the GI tract, when dietary patterns involving different mixed sources of fibre consumed in a single day are considered. The normal gut transit time is 40-60 h. With three meals in a day, fibres and undigested nutrients tend to accumulate in the colon as they traverse from the proximal to the distal colon. There is an evolving need for a paradigm shift in nutritional research to investigate the metabolomic and physiological effects of fibres in combination, as they are consumed in a normal dietary pattern of daily three meals. We propose a research framework to harness the health-beneficial effects of fermentation metabolites of fibre by manipulating the site of colonic fermentation resulting from the interplay between fibre fermentation and transit rates in the colon. Based on this framework, a hypothesis is developed to reduce the side effect of excessive gas production from the colonic fermentation of indigestible oligosaccharides in legumes such as chickpeas and soybean.