Amaranth fiber acts as fermentable substrate for children's fecal microbiota

Fiber has an important role in modulating the intestinal microbiota and its metabolic activity. Since amaranth seeds are a good source of dietary fiber, this study aimed to evaluate the potential prebiotic capacity of fibers obtained from amaranth flour (AFF), a protein isolate (APIF), and a beverage (ABF) to modulate children's fecal microbiota in an in vitro fermentation model. Changes induced in fecal microbiota and the profile of short-chain fatty acids (SCFA) were evaluated after 24, 48, and 72h. APIF and ABF samples reached levels of 60 mM acetate, 35 mM propionate, and 8 mM butyrate, with significant increases in acetate and butyrate at 24 and 72h, and in propionate at the three times evaluated. Regarding AFF, significant increases of SCFA were observed after 72h with levels of 55 mM, 25 mM, and 6 mM for acetate, propionate, and butyrate respectively. Moreover, DGGE profiles at 24h fermentation of amaranth samples showed a high similarity (90%), locating in a cluster separated from inulin and basal medium. However, after 72h fermentation, AFF showed slight differences in the profile with 74% similarity with APIF and ABF. Sequencing results of 24h fermentation of amaranth fibers showed a marked decrease in Fusobacterium and enterobacteria compared with basal medium, accompanied by a significant increase in Bacteroides and Parabacteroides. These results constitute an important contribution in the search for new compounds that promote a healthy gut microbiota. Thereby, the incorporation of these new prebiotics into the diet could lead to the establishment of a widely diverse microbiota usually associated with a healthier state.