GOS (Galactooligosaccharides)
Commonly used for
NutritionConstipationDigestive Health
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What is it? / Overview
GOS is a well-studied prebiotic that promotes the growth of beneficial gut bacteria, particularly bifidobacteria. It may improve bowel regularity and digestive comfort, though gastrointestinal symptoms can occur if introduced too quickly.
How is it used? / Administration
Form: Galactooligosaccharides
Typical dose studied: 2.5–7 g/day
Timing: With meals
One of the best-studied prebiotic fibers. Often combined with probiotics in synbiotic formulations.
How well does it work? / Evidence
~ Moderate evidence
Who should avoid it?
Avoid with: IBS / Irritable bowel syndrome
Already taking it? Increase intake gradually over several weeks.
Research & references
Silk DBA et al. (2009). GOS prebiotic for IBS RCT. Alimentary Pharmacology & Therapeutics. Vulevic J et al. (2015). GOS and gut microbiota/immune function in older adults RCT. American Journal of Clinical Nutrition. An R et al. (2022). Oligosaccharides and glycemic control meta-analysis. Food & Function.
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