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Digestion/Mobility/Weight

Fructooligosaccharides

Prebiotic fiber that feeds beneficial gut bacteria, improves bowel regularity, and enhances calcium absorption for adults with low fiber intake.

Fructooligosaccharides
60
score
B
evidence
Safe
risk

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Quick Take

Worth it if your fiber intake is low — reliably feeds good gut bacteria and may help bones, but expect gas at first.

Fructooligosaccharides (FOS) are short-chain carbohydrates found naturally in chicory root, onions, garlic, and bananas. They resist digestion in the small intestine and are fermented by Bifidobacteria and Lactobacilli in the colon, producing short-chain fatty acids (SCFAs) like butyrate. Clinical studies show FOS increases beneficial gut bacteria, softens stool, and improves bowel movement frequency in people with constipation. FOS also lowers intestinal pH, which can enhance the solubility and absorption of minerals such as calcium and magnesium.

Potential benefits

01
Improves bowel regularity
02
Supports calcium absorption
03
May increase satiety
04
May support glycemic control

Protocol

Amount
5-10 g
Frequency
Once daily
When
Split into 2 doses with meals to reduce bloating, or take once daily with breakfast.

Onset Time

1-2 weeks for bowel regularity; 4-12 weeks for mineral absorption effects

Who Should Consider

Adults with low fiber intake
People with occasional constipation
Postmenopausal women concerned about bone density
Individuals seeking prebiotic support

Food Sources

  • Chicory root (~40% FOS by dry weight)
  • Onions and shallots (~3-6% FOS)
  • Garlic (~4-12% FOS)
  • Bananas (~1% FOS)
  • Wheat and barley (small amounts)

How It Works

FOS passes undigested to the colon, where it serves as a selective substrate for beneficial bacteria—primarily Bifidobacteria—leading to increased fermentation and production of short-chain fatty acids. This acidifies the colonic environment, improving mineral solubility and absorption, and increases stool bulk and water content via osmotic activity and bacterial biomass.

Updated 5/19/2026

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