Architectural and functional changes in the gastrointestinal tract (GIT) following high-fibre diets have been associated with changes in the digestibility of nutrients, in turn affecting the chemosensory mechanisms that orchestrate the hunger-satiety cycle in mammals and birds. Dietary fibre (DF) has been associated with a reduction of the area of absorption and the hydrolytic capacity of the intestinal epithelium. In addition, DF increases the differentiation of stem cells into goblet/secretory cells in detriment of other epithelial cells including enterocytes. As a result, the activity of brush border enzymes declines. This advocates for exogenous enzyme supplementation particularly in high-fibre diets in chicken and pigs. Furthermore, viscous DF prolongs small intestinal transit time and slows down the release and absorption of nutrients. As a consequence, DF causes fluctuations in nutrient availability and sensing along the GIT in non-ruminant animals. These effects, in turn, alter the release patterns of gut peptides (cholecystokinin -CCK-, glucose-dependent insulinotropic polypeptide -GIP-, glucagon like peptide-1 -GLP-1- and peptide tyrosine tyrosine -PYY-). Changes in the sensing mechanism are particularly important for fatty acids (FA) and amino acids (AA) relevant to the enteroendocrine system. The interaction between DF and the chemosensory system needs to be put in context of recent knowledge on feedback signals from the large intestine microbiome. Amongst potential practical applications, this review highlights the role of GIP in adiposity and how that can be used in fattening pigs to help reduce back fat deposition. Some of the more significant effects of DF can be reversed by dietary addition of exogenous enzymes.
Presented at the International Fibre Summit 2019 (https://internationalfibre.com/). Reproduced with permission from the organizers.