How GLP-1 Drugs Reshape Your Gut Bacteria: A Systematic Review of 38 Studies | Research

The takeaway

A systematic review of 38 studies found that GLP-1 drugs significantly alter gut microbiome composition, with each drug showing distinct patterns — liraglutide and dulaglutide generally promoting beneficial bacteria, while semaglutide's effects were more variable.

38 studies analyzed
The first comprehensive systematic review of GLP-1 drug effects on gut microbiota, covering liraglutide, exenatide, dulaglutide, and semaglutide across animal and human models.

What the researchers found

Across 38 included studies, GLP-1 receptor agonists demonstrated notable impacts on gut microbiota composition, richness, and diversity:

- **Liraglutide**: Promoted growth of beneficial genera with metabolic functions

- **Exenatide/Exendin-4**: Increased metabolism-associated genera in animals, but mixed results in humans with some pro-inflammatory genera also increasing

- **Dulaglutide**: Significantly increased Bacteroides, Akkermansia, and Ruminococcus — genera associated with improved metabolic profiles

- **Semaglutide**: Increased Akkermansia muciniphila (positive metabolic functions) but decreased overall microbial diversity; results varied considerably across studies due to population differences and study duration

Why it matters

The gut microbiome influences metabolism, inflammation, appetite, and even brain function. Understanding how GLP-1 drugs alter gut bacteria could reveal new mechanisms explaining their broad health benefits — from weight loss to cardiovascular protection. It could also help predict which patients will respond best and guide microbiome-targeted combination therapies.

How the study worked

PRISMA-guided systematic review searching for studies on the effects of GLP-1 analogues on gut microbiota composition, richness, and abundance. Both animal and human studies were included. Thirty-eight studies met inclusion criteria. Results were synthesized narratively by drug type.

What this study cannot tell us

Results varied considerably between studies due to differences in study populations, drug doses, treatment durations, and microbiome analysis methods. Most human studies were small. The systematic review synthesized results narratively rather than through meta-analysis, limiting quantitative conclusions. It remains unclear whether microbiome changes are a cause or consequence of the metabolic improvements from GLP-1 drugs. Animal model findings may not directly translate to human microbiome responses.

How to read the evidence

This is a PRISMA-guided systematic review of 38 studies — a rigorous evidence synthesis methodology. However, the heterogeneity of included studies and the narrative (non-quantitative) synthesis limit the strength of specific conclusions about individual bacteria or drug effects.

When this study was published

Published in 2025, this is the most current systematic review on this topic and captures the latest microbiome research on all major GLP-1 drugs including semaglutide.

The bigger picture

The gut microbiome has emerged as a key mediator of metabolic health, and the finding that GLP-1 drugs reshape it adds a new dimension to understanding these medications. Akkermansia muciniphila, which increased with both dulaglutide and semaglutide, is one of the most studied 'next-generation probiotics' and is associated with improved insulin sensitivity, reduced inflammation, and better gut barrier function. If GLP-1 drugs achieve some of their benefits by promoting Akkermansia and other beneficial bacteria, this could open the door to microbiome-targeted combination therapies.

Questions still open

Are the microbiome changes caused by GLP-1 drugs a direct effect on gut bacteria, or an indirect result of changes in diet, gastric emptying, and metabolism?
Could baseline gut microbiome composition predict which patients will respond best to specific GLP-1 drugs?
Would combining GLP-1 drugs with probiotics (like Akkermansia supplements) produce enhanced metabolic benefits?

Common questions

Do GLP-1 drugs change your gut bacteria?

Yes, according to this review of 38 studies. Each GLP-1 drug appears to shift the gut microbiome in different ways. Liraglutide and dulaglutide tended to promote beneficial bacteria, while semaglutide boosted Akkermansia (a health-promoting species) but also reduced overall bacterial diversity. These changes may contribute to the metabolic benefits of these medications.

Is the microbiome change from GLP-1 drugs good or bad?

Mostly positive, but it depends on the specific drug. Increases in Akkermansia, Bacteroides, and other metabolism-associated bacteria are generally considered beneficial. However, semaglutide's reduction in overall microbial diversity is a potential concern, as lower diversity is typically associated with poorer gut health. More research is needed to understand the long-term implications.

Read the original research

Effects of GLP-1 Analogues and Agonists on the Gut Microbiota: A Systematic Review.

Nutrients, 17(8)

View on PubMed ↗Publisher’s paper ↗

Citation

Gofron, Krzysztof Ksawery; Wasilewski, Andrzej; Małgorzewicz, Sylwia. (2025). Effects of GLP-1 Analogues and Agonists on the Gut Microbiota: A Systematic Review.. Nutrients, 17(8). https://doi.org/10.3390/nu17081303