Department of Gastroenterology, Ajou University School of Medicine, Suwon, Korea
Copyright © 2026 by The Korean Association for the Study of the Liver
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Authors’ contributions
S.S.K. drafted the manuscript, while J.Y.C. and J.W.E. supervised and approved the final version of the manuscript.
Acknowledgements
This work was supported by the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health and Welfare, Republic of Korea (grant number HR21C1003), and by the National Research Foundation of Korea (NRF), funded by the Ministry of Science and ICT (MSIT), Republic of Korea (grant numbers RS-2022-NR070489, RS-2024-00422549, RS-2025-00521818, and RS-2025-00562556).
Conflicts of Interest
The authors have no conflicts to disclose.
| Strain | Human clinical trial | Population/Indication | Study phase & design | Main outcomes | Relevance to MASLD |
|---|---|---|---|---|---|
| Akkermansia muciniphila | Yes | Overweight/obese adults with insulin resistance [3] | Proof-of-concept RCT; double-blind; 3 months (live vs. pasteurized vs. placebo) (NCT02637115) | Pasteurized form improved insulin sensitivity; reduced fasting insulin, cholesterol, body weight, fat mass, and hip circumference; improvements in AST, ALT, and GGT; well tolerated | Demonstrated metabolic and liver enzyme improvements, suggesting potential relevance for MASLD |
| Adults with overweight/obese type 2 diabetes [4] | Early Phase 2 RCT; double-blind; 12 weeks (NCT04797442) | Reduction in body weight, fat mass, and HbA1c among participants with low baseline A. muciniphila levels | Confirms metabolic benefits; MASLD-specific efficacy not yet evaluated | ||
| Clostridium butyricum (synbiotic with lactulose + Bifidobacterium longum infantis) | Yes | Liver cirrhosis with BMI <25 kg/m² [5] | RCT; 12 weeks (NCT05687409) | Reduction of pathogenic taxa; increase in SCFA-producing bacteria; improvement in metabolic milieu | No MASLD-specific trial; mechanistically relevant via SCFA production |
| Bacteroides thetaiotaomicron | Yes | Adolescents with Crohn’s disease [6] | Randomized, double-blind, placebo-controlled, dose-escalation trial (NCT02704728) | Well tolerated; evidence of colonization; clinical efficacy not assessed | No metabolic or MASLD trials to date |
| Bacteroides ovatus | No | – | – | – | Only preclinical data; no human safety or efficacy studies |
| Bacteroides eggerthii | No | – | – | – | Only preclinical data; strong MASLD-related efficacy in animal models but no human data |
| Bacteroides uniformis | No direct strain-administration trials | Healthy male adults [7] | Randomized, double-blind, placebo-controlled; 9 weeks (placebo vs. flaxseed lignans vs. α-cyclodextrin) | Endogenous B. uniformis increased; improved endurance exercise performance with α-cyclodextrin | No direct supplementation trial; metabolic associations suggest potential MASLD relevance |
| Faecalibacterium prausnitzii | Yes (oxygen-tolerant formulation with Desulfovibrio piger) | Healthy adults [8] | Randomized, double-blind, placebo-controlled (NCT03728868) | Safe; partial engraftment observed | Anti-inflammatory properties support MASLD relevance, but no efficacy trials |
| Coprococcus species | No | – | – | – | Observed in metabolic association studies; no human intervention trials |
This table summarizes only the probiotic strains referenced in the accompanying Editorial, with a focus on their available human clinical evidence and potential relevance to MASLD.[2]
MASLD, metabolic dysfunction-associated steatotic liver disease; ALT, alanine aminotransferase; AST, aspartate aminotransferase; BMI, body mass index; GGT, gamma-glutamyl transferase; HbA1c, hemoglobin A1c; SCFA, short-chain fatty acid; RCT, randomized controlled trial.
| Strain | Human clinical trial | Population/Indication | Study phase & design | Main outcomes | Relevance to MASLD |
|---|---|---|---|---|---|
| Akkermansia muciniphila | Yes | Overweight/obese adults with insulin resistance [3] | Proof-of-concept RCT; double-blind; 3 months (live vs. pasteurized vs. placebo) (NCT02637115) | Pasteurized form improved insulin sensitivity; reduced fasting insulin, cholesterol, body weight, fat mass, and hip circumference; improvements in AST, ALT, and GGT; well tolerated | Demonstrated metabolic and liver enzyme improvements, suggesting potential relevance for MASLD |
| Adults with overweight/obese type 2 diabetes [4] | Early Phase 2 RCT; double-blind; 12 weeks (NCT04797442) | Reduction in body weight, fat mass, and HbA1c among participants with low baseline A. muciniphila levels | Confirms metabolic benefits; MASLD-specific efficacy not yet evaluated | ||
| Clostridium butyricum (synbiotic with lactulose + Bifidobacterium longum infantis) | Yes | Liver cirrhosis with BMI <25 kg/m² [5] | RCT; 12 weeks (NCT05687409) | Reduction of pathogenic taxa; increase in SCFA-producing bacteria; improvement in metabolic milieu | No MASLD-specific trial; mechanistically relevant via SCFA production |
| Bacteroides thetaiotaomicron | Yes | Adolescents with Crohn’s disease [6] | Randomized, double-blind, placebo-controlled, dose-escalation trial (NCT02704728) | Well tolerated; evidence of colonization; clinical efficacy not assessed | No metabolic or MASLD trials to date |
| Bacteroides ovatus | No | – | – | – | Only preclinical data; no human safety or efficacy studies |
| Bacteroides eggerthii | No | – | – | – | Only preclinical data; strong MASLD-related efficacy in animal models but no human data |
| Bacteroides uniformis | No direct strain-administration trials | Healthy male adults [7] | Randomized, double-blind, placebo-controlled; 9 weeks (placebo vs. flaxseed lignans vs. α-cyclodextrin) | Endogenous B. uniformis increased; improved endurance exercise performance with α-cyclodextrin | No direct supplementation trial; metabolic associations suggest potential MASLD relevance |
| Faecalibacterium prausnitzii | Yes (oxygen-tolerant formulation with Desulfovibrio piger) | Healthy adults [8] | Randomized, double-blind, placebo-controlled (NCT03728868) | Safe; partial engraftment observed | Anti-inflammatory properties support MASLD relevance, but no efficacy trials |
| Coprococcus species | No | – | – | – | Observed in metabolic association studies; no human intervention trials |
This table summarizes only the probiotic strains referenced in the accompanying Editorial, with a focus on their available human clinical evidence and potential relevance to MASLD.[
MASLD, metabolic dysfunction-associated steatotic liver disease; ALT, alanine aminotransferase; AST, aspartate aminotransferase; BMI, body mass index; GGT, gamma-glutamyl transferase; HbA1c, hemoglobin A1c; SCFA, short-chain fatty acid; RCT, randomized controlled trial.
