Structure-based standardization of prebiotic soluble dietary fibers based on monosaccharide composition, degree of...

Dietary fibers are diverse indigestible polysaccharides that can be categorized according to their physicochemical properties, including molecular size, monosaccharide composition, and glycosidic bond profile. Fiber promotes health by maintaining intestinal homeostasis. Prebiotic dietary fibers are utilized by microbes in the lower gastrointestinal tract under anaerobic conditions, producing essential metabolites, such as short-chain fatty acids. Microorganisms differ in their ability to hydrolyze and utilize fibers as energy sources, which depends on the microbe's enzymes and the available fiber's physicochemical properties. Thus, different fibers promote specific microbes, in turn modulating metabolite production. As certain taxa provide health benefits and thus are candidates for selective promotion, guidelines for the structure-based standardization of prebiotic fibers are needed to ensure consumer products conform to stated claims and help the prebiotics market transition to more evidence-based prebiotic fiber utilization. We review dietary fiber isolation and purification methods and analyze appropriate structural characteristics for fiber standardization. We propose a stepwise approach to standardization, beginning with monosaccharide composition and eventually adding degree of polymerization and linkage composition, ultimately providing comprehensive structural specifications. We envision a future where standardized, well-characterized dietary fibers are available to consumers and manufacturers, accelerating microbiome and dietary fiber research and improving consumer health.