Fructooligosaccharides

Fructooligosaccharides (FOS) are a class of oligosaccharides composed of short chains of fructose units, usually attached to a glucose residue at one end. They typically contain 2 to 10 monosaccharide units (degree of polymerization DP2–DP10) and are related structurally to inulin. The fructose linkages are generally beta-2,1, which makes these bonds resistant to digestion by human enzymes in the small intestine.

FOS occur naturally in many plants, most notably chicory and Jerusalem artichoke, as well as onions, garlic, leeks, and bananas. They are often extracted from chicory or produced by enzymatic conversion of inulin for use as functional ingredients in foods and dietary supplements.

In the colon, FOS are fermented by gut microbiota, promoting the growth of beneficial bacteria such as bifidobacteria and lactobacilli. Fermentation yields short-chain fatty acids (SCFAs) and gas. As prebiotics, FOS may influence bowel function and mineral absorption, and are associated with modest improvements in stool frequency in some individuals; however effects vary among people.

Uses and safety: FOS are used as dietary fibers and prebiotic ingredients in dairy, baked goods, beverages, and supplements. They are generally regarded as safe when consumed in typical amounts; high doses can cause bloating, flatulence, and intestinal discomfort, particularly in those with sensitive guts or irritable bowel syndrome.

Regulation and research: Regulatory agencies classify FOS as food ingredients and dietary fibers. Research continues on long-term health effects, including impacts on gut health, immune function, and mineral status. No approved medical uses; claims depend on specific products and jurisdictions.