Gut microbiota responses to dietary fibre sources in rats fed starch-based or quasi-human background diets

Abstract The effects of whole foods and food components on gut microbiota are often investigated in animal models not fed a human-type background diet. In this study, rats were fed basal starch (BS) or quasi human (QH) background diets either unsubstituted (controls) or substituted with inulin, dried kiwifruit or pectin for 28 days. Gut microbiota composition and hydrated faecal bulking potential of the diets were evaluated. In the caecum and colon, relative abundance of bacteria at the phylum, family or genus levels differed considerably between the background diets (BS and QH). Rats fed QH diets had higher Actinobacteria than those rats fed BS diets. Gut microbiota responses to inulin, kiwifruit and pectin depended on the background diet. QH diet led to twice the mass of hydrated faecal bulk than BS diet. Overall, simple laboratory animal diets are unlikely to provide valid predictions of effects of prebiotics added to human diets.