Made with Organic Inulin 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. Inulin thus helps to maintain intestinal health and function. Inulin has a very low glycemic index and will not negatively affect serum glucose levels.