Fructo-oligosaccharides (FOS)


Fructo-oligosaccharides (FOS) are sugars found in food items like bananas, asparagus, and garlic. FOS have been used to ease digestion and regulate bacteria. They are often taken with probiotics. FOS can be taken as a pill or powder.


4 to 6 grams daily

What Research Shows

May Not Be Effective

  • Crohn disease —may not have benefit B1

Not Enough Data to Assess

  • Bowel disorders A1

Editorial process and description of evidence categories can be found at EBSCO NAT Editorial Process.

Safety Notes

It is likely safe to take FOS in small doses for a short time, but belly pain may happen. Not enough studies have been done to say whether it is safe to use for a long period or by women who are pregnant or breastfeeding.


Talk to your doctor about any supplements or therapy you would like to use. Some can interfere with treatment or make conditions worse.



A. Bowel Disorders

A1. Paineau D, Payen F, et al. The effects of regular consumption of short-chain fructo-oligosaccharides on digestive comfort of subjects with minor functional bowel disorders. Br J Nutr. 2008;99(2):311-318.

B. Crohn Disease

B1. Benjamin JL, Hedin CR, et al. Randomised, double-blind, placebo-controlled trial of fructo oligosaccharides in active Crohn's disease. Gut. 2011 Jul;60(7):923-929.

Last reviewed July 2019 by EBSCO NAT Review Board Eric Hurwitz, DC