Prebiotic inulin fiber a fructooligosaccharide 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 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.