All fibers are not equal: the effect of dietary fiber on canine gut microbiome

Diet is one of the practical ways to manage long-term health or chronic conditions, especially in companion animals on monotonous diets. The gut microbiome metabolizes macronutrients in the diet into small molecules that affect both microbial community structure and host health. Dietary fiber is a key source of microbe-associated short chain fatty acids and plant secondary metabolites such as polyphenols that affect gastrointestinal physiology and immune processes. Previous studies have found associations between dietary fiber and some key taxa in the canine gut but a mechanistic understanding of interaction between fiber and the canine gut microbiome is currently lacking. The aim of this dietary intervention was to study the effect of varied sources and intakes of dietary fiber on canine gut microbiome and associated health-relevant metabolites. Twelve foods containing different sources and amounts of fiber were included and fed to 18 healthy dogs for a period of 7 days each in a random order. Gut microbiome and fecal metabolome composition was determined from the fecal samples collected on the last day of each food treatment. A total of 226 paired metagenome-metabolome samples were obtained. This study enabled the identification of community-level changes in response to the food treatments, the association of specific microbial and metabolite responses with specific macronutrients as well as the heterogeneity in responses across subjects.