Fructooligosaccharides (FOS)

Fructooligosaccharides (FOS) are short-chain fructose polymers linked by beta-(2,1) glycosidic bonds, which are resistant to human digestive enzymes. They are found naturally in various plants such as chicory, onions, and garlic, or produced commercially from sucrose or inulin. FOS function as prebiotics, selectively stimulating the growth and activity of beneficial colonic bacteria, particularly Bifidobacteria. This microbial fermentation leads to the production of short-chain fatty acids (SCFAs), which play a vital role in maintaining gut barrier integrity and systemic metabolic health. Clinically, FOS are used as dietary supplements to manage constipation, improve mineral absorption, and modulate the gut-immune axis. They are not considered traditional therapeutic targets (such as receptors or enzymes) but are instead bioactive molecules or pharmacological agents administered to influence the host's microbiome. While generally recognized as safe, high intake can lead to gastrointestinal distress, and they are frequently restricted in patients following low-FODMAP diets for irritable bowel syndrome.

Other names

OligofructoseOligofructanFructo-oligosaccharidesNeosugarProfeed

Fructooligosaccharides act as fermentable substrates that escape digestion in the upper gastrointestinal tract and reach the colon. There, they are selectively fermented by beneficial anaerobic bacteria, primarily Bifidobacterium and Lactobacillus species. This fermentation process produces short-chain fatty acids (SCFAs) like acetate, propionate, and butyrate, which lower luminal pH, inhibit the growth of pathogenic bacteria, and provide energy to colonocytes.