prebiotics

Prebiotics are substrates that are selectively utilized by host microorganisms and confer a health benefit. They are typically non-digestible carbohydrates or other compounds that resist breakdown in the upper gastrointestinal tract and reach the colon, where they are fermented by gut bacteria.

The most studied prebiotics include inulin, fructooligosaccharides (FOS), galactooligosaccharides (GOS), resistant starch, pectins, beta-glucans, and arabinoxylans. By serving as food for beneficial microbes, prebiotics promote the growth and activity of bacteria such as Bifidobacterium and Lactobacillus. The fermentation process yields short-chain fatty acids like acetate, propionate, and butyrate, which can influence gut health, immune function, and metabolism.

Health effects attributed to prebiotics include improved bowel regularity and stool quality, enhanced mineral absorption (notably calcium and magnesium), and modulation of immune and inflammatory responses. Observed benefits vary by individual, the specific prebiotic compound, dose, and existing gut microbiota. While many studies report positive outcomes, more rigorous trials are needed to establish specific recommendations for different populations and conditions.

Common dietary sources of prebiotics include chicory root, Jerusalem artichoke, onions, garlic, leeks, bananas (unripe), asparagus, and whole grains such as oats and barley, as well as legumes. Prebiotics are distinct from probiotics (live microorganisms) and synbiotics (combinations of prebiotics and probiotics). They are generally regarded as safe for healthy individuals, though higher doses can cause gas and bloating in some people.