Prebiotics: types, selectivity and utilization by gut microbes

Prebiotics are dietary components selectively utilised by the host's gut microbiota and confer health benefits. They enhance cross-nutritional interactions by supporting beneficial bacteria (particularly Bifidobacterium and Lactobacillus), increase the production of short-chain fatty acids through fermentation, and consequently strengthen the intestinal barrier, balance the immune response, improve metabolic markers (lipid and glucose profiles), regulate key gastrointestinal outcomes such as stool frequency and consistency, and improve some mood/cognitive measures. In early life, human milk oligosaccharides are associated with a Bifidobacterium-dominated ecology and immune development; N-linked and O-linked glycans derived from dietary glycoproteins may exhibit selective utilisation based on binding and species differences; and dietary polyphenols, after limited intestinal absorption, may transform into phenolic metabolites in the colon, shaping the microbiota in a prebiotic-like manner. This review addresses this entire framework, including inulin-type fructans (inulin and fructooligosaccharides), galactooligosaccharides, xylo-oligosaccharides and arabinoxylan-oligosaccharides, isomaltooligosaccharides, lactulose, human milk oligosaccharides, N- and O-linked glycans, and dietary polyphenols as prebiotic-like modulators, with their mechanisms and practical implications.