Prebiotics

What are prebiotics used for?

Updated 4 Nov 2026

Short answer

Prebiotics raise bifidobacteria, a group of gut bacteria, in many trials, but this does not always bring relief from symptoms.[1][2] The evidence differs from use to use:[1][3]

  • Bloating and gas: mixed. A 2019 review of 11 trials found no overall benefit. Flatulence improved at doses of 6 g a day or less and with types other than inulin-type fructans, and got worse with inulin-type fructans.[1]
  • Inflammation: a 2025 review of 90 trials found lower blood markers in adults, but about half of the prebiotic studies in a 2017 review found no drop.[3][4]
  • Gut health and constipation: EFSA concluded that 12 g a day of native chicory inulin raises stool frequency. A 2025 British guideline found that inulin-type fructans softened stools a little and did not change frequency.[5][6]
  • Immune support: 17 trials found fewer people with a respiratory infection, mostly infants and children, with less evidence in adults.[7]
  • Weight: a 2024 review of inulin-type fructans found about 1 kg less weight, with low certainty.[8]
  • Blood sugar: a 2019 review of 33 trials found lower fasting glucose and HbA1c in people with prediabetes or type 2 diabetes.[9]
  • Minerals: single trials found better absorption of calcium in adolescents and of iron from ferrous fumarate in women with low iron stores.[10][11]

Two other uses have little support. Reviews found no significant benefit in irritable bowel syndrome, or for depression.[12][13] For traveler's diarrhea, a 2017 guideline found the evidence insufficient for a recommendation.[14]

Sources (14)

  1. Prebiotics in irritable bowel syndrome and other functional bowel disorders in adults: a systematic review and meta-analysis of randomized controlled trials. Wilson B, Rossi M, Dimidi E, Whelan K Am J Clin Nutr, 2019. PMID 30949662
  2. The Prebiotic Potential of Inulin-Type Fructans: A Systematic Review. Hughes RL, Alvarado DA, Swanson KS, Holscher HD Adv Nutr, 2022. PMID 34555168
  3. The effects of synbiotics surpass prebiotics in improving inflammatory biomarkers in children and adults: A systematic review, meta-analysis, and meta-evidence of data from 5207 participants in 90 randomized controlled trials. Zhang Y, Hong J, Zhang Y, Gao Y, Liang L Pharmacol Res, 2025. PMID 40581234
  4. Short-chain fatty acids, prebiotics, synbiotics, and systemic inflammation: a systematic review and meta-analysis. McLoughlin RF, Berthon BS, Jensen ME, Baines KJ, Wood LG Am J Clin Nutr, 2017. PMID 28793992
  5. Scientific Opinion on the substantiation of a health claim related to "native chicory inulin" and maintenance of normal defecation by increasing stool frequency. European Food Safety Authority, 2015. www.efsa.europa.eu
  6. British Dietetic Association Guidelines for the Dietary Management of Chronic Constipation in Adults. Dimidi E, van der Schoot A, Barrett K, Farmer AD, Lomer MC, Scott SM, et al. J Hum Nutr Diet, 2025. PMID 41081513
  7. The Effects of Prebiotics, Synbiotics, and Short-Chain Fatty Acids on Respiratory Tract Infections and Immune Function: A Systematic Review and Meta-Analysis. Williams LM, Stoodley IL, Berthon BS, Wood LG Adv Nutr, 2022. PMID 34543378
  8. The effects of inulin-type fructans on cardiovascular disease risk factors: systematic review and meta-analysis of randomized controlled trials. Talukdar JR, Cooper M, Lyutvyn L, Zeraatkar D, Ali R, Berbrier R, et al. Am J Clin Nutr, 2024. PMID 38309832
  9. Inulin-type fructans supplementation improves glycemic control for the prediabetes and type 2 diabetes populations: results from a GRADE-assessed systematic review and dose-response meta-analysis of 33 randomized controlled trials. Wang L, Yang H, Huang H, Zhang C, Zuo HX, Xu P, et al. J Transl Med, 2019. PMID 31805963
  10. A combination of prebiotic short- and long-chain inulin-type fructans enhances calcium absorption and bone mineralization in young adolescents. Abrams SA, Griffin IJ, Hawthorne KM, Liang L, Gunn SK, Darlington G, et al. Am J Clin Nutr, 2005. PMID 16087995
  11. Consumption of Galacto-Oligosaccharides Increases Iron Absorption from Ferrous Fumarate: A Stable Iron Isotope Study in Iron-Depleted Young Women. Jeroense FMD, Michel L, Zeder C, Herter-Aeberli I, Zimmermann MB J Nutr, 2019. PMID 31004135
  12. The Efficacy of Probiotics, Prebiotics, Synbiotics, and Fecal Microbiota Transplantation in Irritable Bowel Syndrome: A Systematic Review and Network Meta-Analysis. Wu Y, Li Y, Zheng Q, Li L Nutrients, 2024. PMID 38999862
  13. Effects of Prebiotics and Probiotics on Symptoms of Depression and Anxiety in Clinically Diagnosed Samples: Systematic Review and Meta-analysis of Randomized Controlled Trials. Asad A, Kirk M, Zhu S, Dong X, Gao M Nutr Rev, 2025. PMID 39731509
  14. Probiotics: Usefulness and Safety. NIH National Center for Complementary and Integrative Health, 2019. www.nccih.nih.gov

More about prebiotics

What are prebiotics?Do prebiotics change your gut bacteria?How long do prebiotics take to work?Which foods contain prebiotics?Is a synbiotic better than a prebiotic alone?Are prebiotics the same as fiber?

For education; not medical advice. Talk to a doctor before you start, stop or change a supplement.