Overview
Fructooligosaccharides (FOS) are non-digestible prebiotic fibers that selectively stimulate the growth of beneficial gut bacteria, particularly Bifidobacteria, thereby modulating the intestinal microbiota [4][1]. FOS are fermented in the colon to produce short-chain fatty acids (SCFAs), which lower luminal pH and may improve gut barrier function and reduce inflammation. These mechanisms underlie their potential role in managing gastrointestinal disorders, including inflammatory bowel disease [1]. Some evidence suggests FOS may help regulate blood glucose by improving insulin sensitivity and reducing postprandial glycemia, particularly in animal models, though human data remain inconsistent [2][3]. FOS are commonly derived from sucrose via enzymatic synthesis or extracted from plants and are used in functional foods and supplements for their bifidogenic and metabolic effects [4].
Dosage Guide
Recommended Daily Allowance
For generally healthy individuals
Therapeutic Doses
For treatment of specific conditions
Upper Intake Limit
Maximum safe daily intake
20 g— Higher doses may cause bloating, flatulence, or diarrhea; individual tolerance varies
Special Forms
Alternative forms for specific needs
Enhanced prebiotic synergy; commonly used in functional foods and supplements
High-purity FOS from enzymatic processes; used in clinical and food applications
Clinical Notes
- Start with low doses (2–3 g/day) and gradually increase to minimize gastrointestinal side effects such as bloating and gas.
- Individual tolerance varies; doses above 15–20 g/day may cause abdominal discomfort or osmotic diarrhea.
- FOS may enhance mineral absorption (e.g., calcium), which could be beneficial but requires monitoring in susceptible individuals.
Research
FOS may help counteract dysbiosis in inflammatory bowel disease via modulation of gut microbiota and SCFA production.
FOS consumption is associated with improved glycemic control in some studies, though evidence is mixed.
Limited human RCTs show inconsistent effects of inulin-type fructans (including FOS) on serum glucose levels.
FOS exert a bifidogenic effect and are produced via enzymatic or fermentative methods for use as prebiotics.
FOS are established prebiotics that promote beneficial gut bacteria and are distinct from other fermentable fibers like resistant starch.
Prebiotics like FOS modulate the gut microbiome and may benefit gastrointestinal disorders, though dosing and formulations vary widely.
Malto-oligosaccharides are reviewed but are distinct from FOS; FOS are highlighted as established prebiotics.
FOS are benchmarked against other prebiotics like inulin and galacto-oligosaccharides for probiotic stimulation.
