Fructooligosaccharides (FOS)
A natural prebiotic fiber that selectively feeds beneficial gut bacteria.
Also known as: FOS • Oligofructose
Overview
Fructooligosaccharides (FOS) are a type of soluble prebiotic fiber made up of short chains of fructose molecules. They are found naturally in many plants like chicory root, onions, and bananas. Since humans cannot digest FOS, it travels to the colon intact, where it serves as a food source for beneficial bacteria, particularly Bifidobacteria. This selective feeding helps improve the balance of the gut microbiome, which in turn supports digestive health, mineral absorption, and immune function.
Key Benefits
Promotes Bifidobacteria Growth
FOS is a preferred fuel for Bifidobacteria, helping this key genus to thrive.
Improves Bowel Regularity
As a soluble fiber, it adds bulk to stool and can help relieve constipation.
Enhances Mineral Absorption
Studies show FOS can increase the absorption of calcium and magnesium in the colon.
Dosage & How to Take
3-10 grams per day.
| Purpose | Dose | Notes |
|---|---|---|
| Starting dose | 2-3 grams/day | Start low and increase gradually to assess tolerance. |
| Therapeutic dose | 5-10 grams/day | Divide into 2 doses if needed. |
Best Time to Take
Can be taken anytime, with or without food.
With or Without Food
Can be mixed into food or drinks.
Forms & Bioavailability
| Form | Absorption | Best For | Notes |
|---|---|---|---|
| Powder | N/A (local effect) | Easy dose customization | Dissolves easily in liquids. |
| Capsules | N/A (local effect) | Convenience | Less flexible dosing. |
Side Effects & Safety
Common
- Gas, bloating, and abdominal discomfort, especially at higher doses
Rare
- Diarrhea
Contraindications
- FODMAP intolerance
- Small Intestinal Bacterial Overgrowth (SIBO)
Interactions
FOS is a food-based fiber and does not have known drug interactions.
Scientific Research
FOS as a Prebiotic
A review confirmed that daily intake of FOS significantly increases fecal Bifidobacteria counts in humans.
Food Sources
Frequently Asked Questions
Medical Disclaimer
This content is for educational and informational purposes only and is not intended as medical advice. Always consult with a qualified healthcare professional before starting any supplement regimen, especially if you have pre-existing health conditions or are taking medications. The statements on this page have not been evaluated by the Food and Drug Administration.