The Effect of Arabinogalactan on the Gut Microbiome: A Randomized, Double-blind, Placebo-Controlled, Crossover Trial in Healthy Adults

Abstract Promising evidence suggests beneficial health effects of arabinogalactan but little is known on the effect of this non-digestible carbohydrate on the gut microbiota, a crucial mediator of human health. The objective of this study was to investigate the effect of an arabinogalactan product (ResistAid®) on the fecal microbiome and short chain fatty acids (SCFAs) and gastrointestinal tolerance in healthy adults in a randomized, double-blind, cross-over trial. Thirty adults were randomly assigned to consume 15 g/d maltodextrin (control) or ResistAid® for 6 weeks. At Week 6, and compared to placebo, ResistAid® supplementation led to a significant decrease in the ratio of fecal Firmicutes to Bacteriodetes (F/B) driven by an increase in Bacteriodetes and a decrease in Firmicutes. Moreover, the relative abundance of Bifidobacterium tended to increase with ResistAid® supplementation. Additionally, ResistAid® significantly decreased α-diversity of fecal microbiome. Predicted functional abundances based on 16s rRNA sequences showed that ResistAid® supplementation increased gene abundance of the gut microbiome for α- l -rhamnosidase, β-fructosidase and levanase, as well as tricarboxylic acid and vitamin B6 biosynthesis pathways. Fecal isovaleric, valeric, and hexanoic acids were significantly lower following ResistAid® consumption. There were no statistically significant changes in bowel habit, stool consistency, gastrointestinal tolerance symptoms, chemistry profile, metabolic panel, and vitals, suggesting that consumption of 15 g daily ResistAid® over 6 weeks is safe. These results demonstrate that the gut microbiome composition and predicted functions can be modulated by ResistAid® consumption, suggesting perhaps a mechanistic explanation on its reported benefits in metabolic parameters and the immune system.