Cornstarch fermentation by the colonic microbial community yields more butyrate than does cabbage fiber fermentation; cornstarch fermentation rates correlate negatively with methanogenesis.

Fermentations of cornstarch and a cabbage-fiber preparation by human fecal suspensions were studied. The molar percent of butyrate of total short-chain fatty acid products was significantly higher when cornstarch was the substrate. Higher molar percents of butyrate were also produced from cornstarch as compared with endogenous substrate when rat fecal suspensions were used. A range of cornstarch fermentation rates was found with suspensions from 20 human subjects. Rapid fermentaion was associated with the absence of methane production. Methane-negative rat fecal suspensions also fermented cornstarch more rapidly than did methane-positive suspensions. High butyrate production may be important because butyrate provides energy to colonocytes and it regulates differentiation of cultured cells.