Barley Products of Different Fiber Composition Selectively Change Microbiota Composition in Rats

Scope: Several dietary fiber properties are suggested to be important for the profiling of the microbiota composition, but those characteristics are rather unclear. Whether different physico-chemical properties of barley dietary fiber influence the gut microbiota composition is investigated. Methods and results: Seven diets containing equal amounts of dietary fiber from barley malts, brewer's spent grain (BSG), and barley extracts, resulting in varying amounts of β-glucan, soluble arabinoxylan, and insoluble arabinoxylan in the diets were given to conventional rats. Malts increased microbiota alpha diversity more than BSG and the extracts. The intake of soluble arabinoxylan was related to Akkermansia and propionic acid formation in the cecum of rats, whereas β-glucan and/or insoluble arabinoxylan were attributed to some potentially butyrate-producing bacteria (e.g., Lactobacillus, Blautia, and Allobaculum). Conclusion: This study demonstrates that there is a potential to stimulate butyrate- and propionate-producing bacteria in the cecum of rats with malt products of specific fiber properties. Moreover, BSG, a by product from beer production, added to malt can possibly be used to further modulate the microbiota composition, toward a higher butyric acid formation. A complex mixture of fiber as in the malts is of greater importance for microbiota diversity than purer fiber extracts.