The Connection Between Gut Health and Your Liver
You have definitely heard of the gut-brain axis.
You may have even heard of the gut-skin axis.
But chances are you have probably never heard of the gut-liver axis.
Honestly, I had not either until I began researching fatty liver disease more extensively to write my latest book on fatty liver disease, and noticed something interesting: supplements commonly associated with gut health—particularly prebiotics and probiotics—were repeatedly being studied for their role in improving liver health.
That is a pretty significant finding considering approximately 1 in 4 North Americans is estimated to be living with non-alcoholic fatty liver disease (NAFLD), and currently, there is no universally approved pharmaceutical treatment specifically for the condition. The idea that gut-focused interventions may influence liver health highlights just how interconnected the body truly is.
Why Are Probiotics and Prebiotics Being Studied for Liver Health?
Interest in the gut-liver connection has grown rapidly in recent years, particularly in relation to NAFLD.
The 2020 ESPEN Clinical Practice Guidelines for liver disease formally endorsed probiotics as a strategy that may help reduce liver enzymes in individuals with NAFLD.
That is notable because major clinical guidelines are generally cautious about recommending supplements unless meaningful evidence exists. As research into the microbiome continues evolving, the liver has emerged as one of the organs most directly affected by gut health.
An Introduction to the Gut-Liver Axis
The liver and gastrointestinal tract are closely connected through a major blood vessel called the portal vein. The portal vein carries blood directly from the digestive tract to the liver, creating a continuous two-way relationship between the gut and liver. This connection allows the liver to process nutrients, metabolites, toxins, bacterial products, and inflammatory compounds absorbed from the digestive tract.
At the same time, the liver influences digestion through:
- Bile acid production
- Immune regulation
- Nutrient metabolism
- Detoxification processes
Because of this close relationship, disturbances within the gut microbiome may directly influence liver health.
What Happens When Gut Health Is Disrupted?
The gut microbiome plays a major role in maintaining a healthy gut-liver relationship.
When gut dysbiosis occurs—meaning there is an imbalance in gut bacteria—it may contribute to increased inflammation and impaired intestinal barrier function. Researchers currently believe dysbiosis may affect liver health through two major mechanisms.
Harmful Metabolites and Inflammation
Beneficial gut bacteria tend to produce compounds such as short-chain fatty acids (SCFAs), which may support intestinal and metabolic health. Less beneficial bacteria, however, may produce more pro-inflammatory compounds.
These metabolites can travel through the portal vein directly to the liver, where they may contribute to inflammation and liver damage. Liver inflammation is one of the defining features of NAFLD.
Increased Intestinal Permeability
Dysbiosis weakens the intestinal barrier, making the effects of the above more pronounced, as this barrier otherwise plays an important role in preventing problematic bacteria (and their metabolites) from entering the portal vein and reaching the liver, which in turn can elicit a damaging immune response.
What Does the Research on Probiotics Show?
Research examining probiotics in NAFLD has become increasingly promising.
A 2020 systematic review and meta-analysis published in Scientific Reports found that probiotic supplementation reduced several inflammatory markers associated with fatty liver disease, including:
- Tumor necrosis factor-alpha (TNF-α)
- C-reactive protein (CRP)
These findings suggest that improving gut microbiome balance may help reduce inflammation associated with fatty liver disease.
In many of these studies, researchers used multi-strain probiotic supplements containing species of:
- Lactobacillus
- Bifidobacterium
Prebiotics commonly include fibers such as:
- Fructooligosaccharides (FOS)
- Inulin
Gut Health Beyond Supplements
It is important to note that probiotics and prebiotics are only one piece of the larger gut health picture. Gut microbiome health is also influenced by:
- Dietary patterns
- Fiber intake
- Sleep quality
- Stress management
- Physical activity
- Alcohol intake
- Medication use
- Overall lifestyle habits
Supporting gut health through a balanced dietary pattern rich in plant foods and fiber, along with microbiome-supportive habits, may have implications far beyond digestion alone.
Why This Matters
The growing understanding of the gut-liver axis reinforces an important concept in digestive health:
The gut does not operate independently from the rest of the body.
The health of the microbiome may influence inflammation, immune function, metabolism, and organ health throughout the body—including the liver. As rates of fatty liver disease continue increasing globally, understanding the role gut health may play in prevention and management becomes increasingly important.
Final Thoughts & Future Directions
The relationship between gut health and liver health is real, clinically relevant, and continuing to evolve as research expands. The gut-liver axis highlights how dysbiosis, inflammation, and intestinal permeability may contribute to liver dysfunction and the progression of fatty liver disease.
Emerging evidence suggests that probiotics, prebiotics, and broader microbiome-supportive habits may positively influence liver health, particularly in individuals with NAFLD. While research is still developing, one thing is becoming increasingly clear: supporting your gut health may support far more than just digestion.
- Bischoff, S. C., Bernal, W., Dasarathy, S., Merli, M., Plank, L. D., Schütz, T., & Plauth, M. (2020). ESPEN practical guideline: Clinical nutrition in liver disease. Clinical nutrition (Edinburgh, Scotland), 39(12), 3533–3562. https://doi.org/10.1016/j.clnu.2020.09.001
- Kirpich, I. A., Marsano, L. S., & McClain, C. J. (2015). Gut-liver axis, nutrition, and non-alcoholic fatty liver disease. Clinical biochemistry, 48(13-14), 923–930. https://doi.org/10.1016/j.clinbiochem.2015.06.023
- Konturek, P. C., Harsch, I. A., Konturek, K., Schink, M., Konturek, T., Neurath, M. F., & Zopf, Y. (2018). Gut⁻Liver Axis: How Do Gut Bacteria Influence the Liver?. Medical sciences (Basel, Switzerland), 6(3), 79. https://doi.org/10.3390/medsci6030079
- Pan, X., Wen, S. W., Kaminga, A. C., & Liu, A. (2020). Gut metabolites and inflammation factors in non-alcoholic fatty liver disease: A systematic review and meta-analysis. Scientific reports, 10(1), 8848. https://doi.org/10.1038/s41598-020-65051-8
- Song, Q., & Zhang, X. (2022). The Role of Gut-Liver Axis in Gut Microbiome Dysbiosis Associated NAFLD and NAFLD-HCC. Biomedicines, 10(3), 524. https://doi.org/10.3390/biomedicines10030524
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