Fiber
FOS (Fructooligosaccharides)
Also known as: Fructooligosaccharides, Oligofructose
Short-chain prebiotic fiber that rapidly feeds bifidobacteria. More gas-producing than longer-chain fibers.
Last reviewed June 2026 · Evidence graded from peer-reviewed research, not editorial opinion. Educational only — not medical advice.
Primary uses
- Prebiotic
- Bifidobacteria support
- Calcium absorption
How it works
- Rapidly fermented by bifidobacteria
- Increases SCFA production
- Enhances calcium absorption
Dosage
- Typical range
- 2-8 g daily
- Timing
- Any time
- With food
- Optional
- Duration
- Start very low
- Special populations
- FODMAP-sensitive avoid
Forms
- Powder
- Capsules
Safety
Common side effects
- Gas
- Bloating
- Cramping
Contraindications
- SIBO
- FODMAP intolerance
Evidence notes
Effective prebiotic, may cause gas
Grade B: Some human trials support key claims; further confirmation needed.
Related in Fiber
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Medical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider. Individual needs and risks vary — consult a professional before starting, stopping, or combining supplements, especially if you are pregnant or nursing, taking medication, or managing a health condition.