Perspectives on structurally complex dietary fibers as alternatives to traditional prebiotics in the modulation of the gut microbiome

Recent advances in food science highlight the critical role of dietary fibers (DFs) as modulators of the gut microbiota, potentially serving as alternatives to traditional prebiotics such as inulin, fructooligosaccharides, and galactooligosaccharides. DFs exhibit complex physicochemical characteristics, influencing their fermentability, solubility, and subsequent effects on microbial diversity and metabolic activity. Understanding how specific DFs, including arabinoxylans, pectins, and β-glucans, interact with commensal microorganisms remains key to identifying novel prebiotic candidates. This review integrates current evidence regarding the prebiotic potential of various DFs, emphasizing their structural features, fermentation patterns, and production of short-chain fatty acids (SCFAs). It also explores synergistic effects between insoluble fibers and phenolic compounds, the modulation of the gut–brain axis through microbiota-mediated pathways, and industrial strategies for developing functional ingredients derived from agro-industrial by-products. Arabinoxylans, pectins, and β-glucans demonstrate selective fermentation and the ability to modulate beneficial taxa such as Bifidobacterium , Roseburia , and Faecalibacterium , with concomitant increases in acetate, propionate, and butyrate production. Emerging evidence supports the classification of these compounds as next-generation prebiotics (NGPre). However, further well-designed clinical studies and structure–function analyses are required to define the parameters that characterize DFs as NGPre. Their sustainable sourcing, low cost, and Generally Recognized as Safe (GRAS) status position DFs as promising, safe, and effective alternatives for microbiota modulation and functional food innovation.