Investigating the influence of dietary fibre on intestinal health
thesisposted on 2022-03-28, 23:26 authored by Raymond Wei Wern Chong
Increasing the consumption of dietary fibre has long been implicated in the maintenance of intestinal health and the reduced risk of non-communicable diseases including type 2 diabetes, cardiovascular disease and colorectal cancer. As a category, dietary fibre encompasses a variety of molecules that comprise a diverse range of physical properties and physiological activities. To examine the effect of chemical composition on physiological activity, three dietary fibres were characterised and compared. NutriKane™, a fibre derived from sugarcane was an insoluble fibre and contained chromium and manganese, which are rarely found in foods, and phenolic compounds with antioxidant activity. In comparison, Benefiber™ and psyllium husk, while both soluble fibres exhibited drastically different physical properties due to their characteristic carbohydrate content. To further investigate the effect of dietary fibre on intestinal health, we compared the effects of these fibres on the gut microbiota and mucus layer using in vitro and in vivo systems respectively. In contrast to Benefiber™ and psyllium husk, which were readily fermented in vitro, NutriKane™ was less effective in stimulating short chain fatty acid production emphasizing significant differences in the metabolic activity of soluble and insoluble dietary fibres. We next characterised the glycosylation of MUC2, the major component of the mucus layer, from C57BL/6 mice given 60% fat diets modified with dietary fibre. We found that dietary fibre modification, but not high fat content is able to alter MUC2 glycosylation highlighting a novel interaction between diet and the host mucus layer. Our findings demonstrate that not all dietary fibres are equal and variations in carbohydrate content contribute to the unique physical properties and metabolic activity of fibres. Overall our findings highlight the complexity of interactions between diet, the gut microbiota, and the host mucus layer and support the development of intuitive dietary interventions for the improvement of intestinal health.