Inulin, a fructooligosaccharide (FOS), is a soluble prebiotic fiber that is resistant to digestion and reaches the large intestine essentially intact. Intestinal probiotic bacteria consume inulin and in turn, produce the short-chain fatty acids (SCFAs) that nourish the cells ...Inulin, a fructooligosaccharide (FOS), is a soluble prebiotic fiber that is resistant to digestion and reaches the large intestine essentially intact. Intestinal probiotic bacteria consume inulin and in turn, produce the short-chain fatty acids (SCFAs) that nourish the cells lining the colon.