Gut microbiota modulates NAFLD progression via regulation of gluconeogenesis

If you've been told your liver is "fatty" and left to sort out why on your own, a new synthesis in the journal Pharmacological Research offers a fresh piece of the puzzle: your gut bacteria may be quietly steering how much sugar your liver manufactures, and that sugar-making process may be part of what tips a liver toward disease. The review doesn't report a single new experiment. Instead, it pulls together years of animal, human, and clinical-trial data into one proposed model of how the gut and liver talk to each other, and it's a model with real implications for the roughly 1 in 4 adults worldwide living with fatty liver disease.

Key takeaways:

• Researchers propose a "gut microbiota-gluconeogenesis-NAFLD axis": gut bacteria and their byproducts may help regulate a liver process called gluconeogenesis (the liver's manufacture of new glucose), and disruption of that signal is linked to fatty liver disease and its progression.
• This is a conceptual model built from existing evidence, not proof from a single new trial — the underlying data blend mouse experiments, human cohort studies, and small clinical trials of varying quality.
• Practical levers already under study include fiber, prebiotics, and fecal microbiota transplantation (FMT), but none is an established treatment yet.
• The biggest caveat: most human evidence is correlational, and the field still struggles with inconsistent methods across studies.

The Gut Microbiota-Gluconeogenesis-NAFLD Axis Explained

The review's central claim is that nonalcoholic fatty liver disease (NAFLD, a buildup of fat in the liver not caused by heavy alcohol use, now often called MASLD for "metabolic dysfunction-associated steatotic liver disease") is shaped in part by a tug-of-war between two glucose-making systems: the liver's own gluconeogenesis and a lesser-known process called intestinal gluconeogenesis (IGN), in which the gut itself makes a small amount of glucose. Under normal conditions, IGN sends a signal through the gut-brain-liver nerve circuit that tells the liver to ease off its own glucose production, according to the review, published by Wang and colleagues (DOI: 10.1016/j.phrs.2026.108444). In insulin-resistant states, that braking signal appears to weaken. The authors argue that gut bacteria and the metabolites they produce, including short-chain fatty acids (SCFAs, byproducts of bacteria fermenting fiber) and bile acids, help decide which way this balance tips, acting through molecular pathways with names like FXR, TGR5, and FFAR3.

Fatty Liver Disease's Growing Toll on Metabolic Health

Fatty liver disease is not a niche condition: the review cites global prevalence of roughly 25.2%, climbing to 27.4% in Asia and above 33% in some Chinese cohorts. It rarely travels alone. NAFLD clusters tightly with type 2 diabetes, obesity, and metabolic syndrome, and the review frames it as a genuinely two-way street: insulin resistance drives fat into the liver, and a fatty, inflamed liver worsens blood sugar control in return. For anyone already managing prediabetes, type 2 diabetes, or metabolic syndrome, that means fatty liver disease isn't a separate problem to track, it's often part of the same underlying process, and the gut may be one of the levers connecting them.

Piecing Together Mouse Models, Cohorts, and Small Trials

Because this is a review rather than a single study, its credibility rests on how much independent evidence points the same direction. The authors marshal genetic mouse studies (animals engineered to have more or less intestinal gluconeogenesis), human microbiome sequencing cohorts, and several small clinical trials. One frequently cited example: in independent mouse work on intestinal gluconeogenesis, animals engineered to have boosted IGN were protected from high-fat-diet-induced liver fat buildup and had better blood sugar control, while mice lacking intestinal glucose-sensing machinery lost that protection. On the human side, a five-year follow-up study of 1,282 participants by Frost and colleagues found that NAFLD, diabetes, and poor glycemic control tracked closely with an unstable gut microbiome, marked by rising levels of opportunistic bacteria like Enterobacteriaceae. That's a large, real-world cohort, but it shows association over time, not proof that the microbiome shift caused the liver disease.

What This Could Mean for Someone Managing Fatty Liver Disease

None of this justifies rushing out for a specific probiotic or supplement marketed as a fatty-liver cure. The review does not establish any single probiotic strain, prebiotic fiber, or "gut reset" as a proven treatment. What it does suggest is that the diet-microbiome-liver connection you may have already suspected has real mechanistic backing worth discussing with a doctor. Fiber-rich diets that feed SCFA-producing bacteria are consistently linked, across the studies reviewed, to better gut barrier function and lower hepatic fat, while diets high in choline from red meat and processed sources are linked to a compound called TMAO and worse NAFLD severity. If you have fatty liver disease, type 2 diabetes, or metabolic syndrome, this is a reasonable basis to ask your clinician about dietary fiber and metabolic workup, not a green light to self-treat with unregulated supplements.

Bile Acids and Bacterial Signatures Tied to Disease Severity

The review highlights specific, measurable signals that track with worse disease. In patients with nonalcoholic steatohepatitis (NASH, the more aggressive inflammatory form of fatty liver disease), the ratio of secondary to primary bile acids shifts unfavorably, and one cited analysis found that a higher secondary-to-primary bile acid ratio was associated with 42% lower odds of higher disease activity scores and 43% lower odds of significant liver scarring (fibrosis). Bacterial signatures differ by patient subgroup too: non-obese NAFLD patients showed a distinct pattern (more Veillonellaceae, less Ruminococcaceae, and higher fecal bile acids) as fibrosis worsened, a pattern not seen in obese patients with the same diagnosis. That subgroup difference is itself a caveat: a single microbiome signature likely won't apply to everyone with fatty liver disease.

What Remains Unproven About the Gut-Liver Sugar Circuit

The review is candid about its limits. Much of the human evidence is observational, meaning it can show that gut bacteria and liver disease severity move together without proving the bacteria are driving the disease rather than merely reflecting it. Study methods vary widely, different labs sequence different regions of bacterial DNA, use different analysis pipelines, and diagnose NAFLD with anything from blood tests to liver biopsy, which the authors say makes results hard to compare directly. Confounding is a persistent problem too: obesity, diabetes, and diet each independently reshape the gut microbiome, and few studies fully separate those effects from any direct microbiome-to-liver signal. Even therapies with the most direct trial evidence come with caveats: the FXR-targeting drug obeticholic acid improved liver histology in the randomized, placebo-controlled FLINT trial, yet full NASH resolution occurred in only about 22% of treated patients, alongside a worsened cholesterol profile.

Where Gut-Microbiome-Targeted Fatty Liver Therapies Go Next

The translational path the review points to involves testing whether restoring the gut's glucose-sensing signal, rather than just changing which bacteria are present, actually improves liver outcomes. Early leads include prebiotic fibers and traditional Chinese medicine polysaccharides, most of which are barely absorbed on their own; one trial found oral bioavailability as low as 8.91%, meaning over 90% of their effect depends on gut bacteria fermenting them first. Fecal microbiota transplantation (FMT) trials offer a preview of what's possible and how far there is to go: in one placebo-controlled trial using lean vegan stool donors, FMT reduced liver inflammation scores on repeat biopsy, and in a separate trial in people with metabolic syndrome, lean-donor FMT increased the beneficial, butyrate-producing bacterium Roseburia intestinalis by 2.5-fold alongside improved insulin resistance. Researchers are also exploring whether a patient's starting gut bacteria composition, rather than which prebiotic they're given, better predicts who will actually respond, a step toward personalized rather than one-size-fits-all treatment.

Common Questions

Is fatty liver disease caused by gut bacteria? Not established as a single cause. The review proposes gut bacteria and their metabolites as one contributing factor operating through the liver's glucose-making pathways, alongside diet, obesity, and insulin resistance, not as the sole trigger of fatty liver disease.

Can prebiotics or fiber treat fatty liver disease? Fiber and prebiotics are linked in the cited studies to better gut barrier function and lower liver fat, but they are not established as a proven treatment for existing fatty liver disease, and no specific product should be treated as a cure.

Is fecal microbiota transplant (FMT) a treatment option for fatty liver disease? FMT remains investigational for fatty liver disease. Small trials have shown improvements in liver inflammation markers and insulin resistance, but it is not an approved or standard treatment outside research settings.

What's the difference between NAFLD and MASLD? MASLD (metabolic dysfunction-associated steatotic liver disease) is the newer name for the condition long called NAFLD, adopted by a 2023 multisociety Delphi consensus to center the metabolic risk factors, such as obesity or type 2 diabetes, that typically drive it.

References

1. WeiZhou Wang, YunTao Tang, ZiQian Wan, et al. (2026). Gut microbiota modulates nonalcoholic fatty liver disease (NAFLD) progression via regulation of gluconeogenesis: mechanisms and translational research. Pharmacological Research. https://doi.org/10.1016/j.phrs.2026.108444
2. Justine Vily-Petit, Maud Soty-Roca, Marine Silva, et al. (2020). Intestinal gluconeogenesis prevents obesity-linked liver steatosis and non-alcoholic fatty liver disease. Gut. https://doi.org/10.1136/gutjnl-2019-319745
3. Brent A Neuschwander-Tetri, Rohit Loomba, Arun J Sanyal, et al. (2015). Farnesoid X nuclear receptor ligand obeticholic acid for non-cirrhotic, non-alcoholic steatohepatitis (FLINT): a multicentre, randomised, placebo-controlled trial. The Lancet. https://doi.org/10.1016/s0140-6736(14)61933-4
4. Kim Sui Wan, Wah-Kheong Chan, Muhammad Fadhli Mohd Yusoff, et al. (2024). Correspondence: “A multisociety Delphi consensus statement on new fatty liver disease nomenclature”. Annals of Hepatology. https://doi.org/10.1016/j.aohep.2024.101485