- Polysaccharides as prebiotics have emerged as an important focus in nutrition and medical research, owing to their ability to beneficially modulate the gut microbiota and, in turn, influence host health.
- Prebiotics are defined as non-digestible food components that selectively stimulate the growth and activity of beneficial microorganisms in the gastrointestinal tract. Many polysaccharides—such as inulin, fructooligosaccharides, galactooligosaccharides, resistant starch, arabinoxylans, and β-glucans—fit this definition. They resist enzymatic digestion in the upper gastrointestinal tract and reach the colon intact, where they become substrates for fermentation by gut microbes. This fermentation produces metabolites that support intestinal and systemic health, making polysaccharides crucial dietary components beyond their role as simple fibers.
- In the gut microbiota, polysaccharides function as selective energy sources for specific bacterial populations, particularly Bifidobacterium and Lactobacillus. The fermentation of these substrates results in the production of short-chain fatty acids (SCFAs) such as acetate, propionate, and butyrate. SCFAs not only serve as energy sources for colonocytes but also regulate immune function, enhance intestinal barrier integrity, and modulate inflammatory responses. Butyrate, for example, is a key fuel for colonocytes and has anti-inflammatory and anti-carcinogenic properties. Propionate contributes to gluconeogenesis in the liver, while acetate enters peripheral circulation to influence lipid metabolism. Thus, the fermentation of prebiotic polysaccharides creates a biochemical bridge between diet, microbiota composition, and host physiology.
- The health benefits of polysaccharide-based prebiotics extend across multiple systems. They improve digestive health by promoting regular bowel movements and reducing the risk of constipation. By encouraging the growth of beneficial microbes, they help suppress pathogenic bacteria through competitive exclusion and antimicrobial metabolite production. Polysaccharide prebiotics are also linked to improved metabolic outcomes, including better glycemic control, lower serum cholesterol, and reduced risk of obesity-related disorders. Moreover, they contribute to immune modulation by enhancing mucosal immunity and regulating inflammatory pathways. Emerging evidence even suggests that polysaccharide prebiotics influence the gut–brain axis, potentially affecting mood, cognition, and stress responses.
- In infant nutrition, prebiotic polysaccharides play a particularly crucial role. Human milk oligosaccharides (HMOs), naturally occurring complex carbohydrates in breast milk, are essential in shaping the early-life microbiota by favoring Bifidobacterium dominance. Because replicating the complexity of HMOs is challenging, infant formulas are often supplemented with plant-derived oligosaccharides such as galactooligosaccharides (GOS) and fructooligosaccharides (FOS), which mimic some of the prebiotic functions of HMOs and support immune and digestive development in infants.
- From an industrial and dietary perspective, polysaccharides as prebiotics have wide applications in functional foods, nutraceuticals, and dietary supplements. They are incorporated into yogurts, cereals, beverages, and baked products to enhance fiber content and promote gut health. Their natural origin and multiple health benefits also make them attractive alternatives to synthetic supplements. Advances in food technology are enabling the development of customized prebiotic blends that target specific microbial populations or health outcomes.
