Impact of dietary pattern of the fecal donor on in vitro fermentation properties of whole grains and brans

Because diet influences gut microbiota composition and function, the purpose of this study was to determine how fecal donor diet impacts in vitro fermentation properties of whole grain flours and brans from corn, oats, rye, and wheat. Samples were fermented with fecal microbiota from subjects with similar energy intakes but differing in intakes of several beneficial nutrients (G1 > G2). Shifts in the microbiota during fermentation were a function of diet group and time. Fecal microbiota from G1 subjects showed less decrease in diversity during fermentation and these microbiotas showed higher carbohydrate utilization and butyrate production compared with microbiota from G2 subjects. More carbohydrates were fermented from whole grains than brans. Rye induced high carbohydrate fermentability and butyrate production accompanied by low ammonia production, but only when using fecal microbiota from G1 subjects. Thus, diet quality influences the ability of the microbiota to ferment carbohydrates, differentiate among grains, and produce butyrate.