This is an excellent product and good example of a prebiotic being used together with a probiotic, a concept being called synbiotics. There are many ingredients that we now have a better understanding of that work as prebiotics, not all of them are fibers.These ingredients selectively work on parts of the microbiome to create a health benefit. (a substrate that is selectively utilized by host microorganisms conferring a health benefit. - current ISAPP definition - https://isappscience.org/prebiotic-definition-updated-isapp/)