Table of contents
- 1. The liver – a true superstar
- 2. Bile – the underestimated key to healthy digestion
- 3. The connection between the gut and the liver
- 4. How the gut and liver communicate
- 5. The liver under constant stress
- 6. What the microbiome has to do with leaky gut and liver health
- 7. How gut bacteria can harm your liver health
- 8. The link between the gut–liver axis and NAFLD
- 9. Consequences for the liver
- 10. How to support your liver
Our gut is home to trillions of microorganisms that act like an invisible control centre for our health.
The gut, liver and immune system are in constant, close communication with each other. When this delicate balance is disrupted by factors such as a high-fat diet, alcohol consumption or excessive stress, the intestinal barrier can become weakened. As a result, bacterial components and metabolic by-products can more easily reach the liver, where they may trigger inflammation and promote or worsen liver disease. This exact interplay between the microbiome (gut flora) and the liver is increasingly becoming a focus of scientific research and is opening up new ways to support liver health via the gut in a targeted manner (1).
In this blog article, you’ll discover the key facts on this topic – explained in 10 points:
1. The liver – a true superstar
Did you know that the liver is one of the hardest-working organs in your body? Many people mainly think of it as a “detox organ”, usually in connection with alcohol. In reality, the liver does far more than that. It breaks down not only alcohol, but also numerous metabolic waste products, medications and harmful substances from food and the environment, making them easier for the body to eliminate.
At the same time, the liver is a vital production site: it produces important proteins, including those needed for blood clotting when you cut yourself. In addition, the liver produces bile – an indispensable fluid for fat digestion and the absorption of fat-soluble vitamins (2).
2. Bile – the underestimated key to healthy digestion
Bile is a greenish-yellow digestive fluid produced in the liver and is essential for proper digestion. It contains several components, most importantly bile acids. These ensure that fats and fat-soluble vitamins from food can be broken down and absorbed through the intestinal lining.
If bile acids are lacking or do not reach the gut in sufficient amounts, these valuable nutrients cannot be properly absorbed. This can lead to nutrient deficiencies, fatty stools and digestive problems such as diarrhoea (2).
3. The connection between the gut and the liver
So your gut clearly depends on the liver – and the two organs are closely connected in several ways. One important link is via the bile ducts: the liver produces bile and releases it either into the gallbladder for storage or directly into the small intestine, where it is immediately used for digestion.
In addition, the gut and liver are in constant exchange via the bloodstream. A central role is played by the portal vein, which transports nutrients absorbed in the gut directly to the liver. This means that almost everything we absorb from food – from sugars and fats to potential toxins – passes through the liver first before reaching the rest of the body. This is why the liver is often described as the body’s central metabolic control and filtration hub (2).
A colourful, fibre-rich diet supports both gut health and liver health.
4. How the gut and liver communicate
However, it is not only nutrients that travel between the gut and the liver – important signalling molecules are constantly exchanged as well. In this way, the two organs remain in close communication and fine-tune their activity to one another. Bile acids are particularly fascinating in this context. After they bind fats and fat-soluble vitamins in the intestine, most of them (up to 95%) are reabsorbed and transported back to the liver via the bloodstream. For the liver, this acts as an important signal: it “senses” how many bile acids are already in circulation and adjusts its own production accordingly. At the same time, specialised cells in the gut detect bile acid levels and send additional signals to the liver, further refining this regulatory loop. This creates a highly precise communication system between the gut and the liver (2).
5. The liver under constant stress
Through these transport pathways, not only nutrients reach the liver, but also harmful substances such as alcohol and toxins from food. In the liver, these substances are filtered and broken down as effectively as possible so they cannot harm the rest of the body. This detoxification work is essential for survival, but it also places a significant burden on the liver. The fewer harmful substances that reach it, the better the liver can carry out its many tasks and remain healthy.
Two factors play a key role here. On the one hand, it is important to minimise the intake of harmful substances – for example by limiting alcohol and highly processed foods. On the other hand, the intestinal barrier is crucial. When intact, it acts like a finely tuned filter. If it is weakened, as in leaky gut syndrome, more unwanted substances and bacterial components can enter the bloodstream and place additional strain on the liver (2). Would you like to learn more about leaky gut? Then this blog article might be of interest to you: Leaky Gut – and Why a Healthy Gut Barrier Matters
When the microbiome is out of balance and the intestinal lining is weakened, unwanted substances can pass through the portal vein to the liver. If the liver becomes overwhelmed, the immune system triggers inflammatory responses and liver damage may follow.
6. What the microbiome has to do with leaky gut and liver health
We now know that the liver and gut work closely together. But what role do your gut bacteria play in this? When the intestinal barrier is weakened, this is usually due to several factors. Alcohol, stress, an unhealthy diet and long-term antibiotic use can alter the microbiome in a way that promotes inflammation and leaky gut. For example, bacteria that produce the short-chain fatty acid butyrate – which is essential for a healthy intestinal barrier – often decrease. As a result, the intestinal lining becomes more permeable, allowing increasing amounts of harmful substances and bacterial components to enter the bloodstream and reach the liver, where they can cause damage (2).
In order for you to stay fit and healthy, your liver must also be healthy!
7. How gut bacteria can harm your liver health
Once bacteria and their components reach the liver, they stimulate the immune system and can trigger inflammatory reactions. In response to ongoing inflammation, the liver begins to remodel its tissue. In many liver diseases, valuable liver cells that are responsible for detoxification or bile acid production are lost and replaced by non-functional connective tissue. This irreversible process is known as liver fibrosis. In the worst case, fibrosis can progress to liver cancer (3).
8. The link between the gut–liver axis and NAFLD
Non-alcoholic fatty liver disease (NAFLD) is closely linked to overweight, insulin resistance and type 2 diabetes, and is estimated to affect up to one third of the global population. In NAFLD, excess fat accumulates in the liver. Over time, this can lead to inflammation and scarring of liver tissue (liver fibrosis), increasingly impairing liver function.
Gut health plays a key role in this process. Studies show that people with NAFLD often have alterations in their gut microbiome, a weakened intestinal barrier, and elevated levels of bacterial components such as lipopolysaccharides (LPS) circulating in the blood. These substances travel from the gut to the liver, where they can amplify inflammatory processes. In addition, small intestinal bacterial overgrowth (SIBO) occurs more frequently. You can learn more about this here: SIBO – Causes and Symptoms of Small Intestinal Bacterial Overgrowth.
Lipid metabolism is also involved. Certain fat molecules, such as ceramides, can damage the liver when present in high concentrations. Gut bacteria influence how many of these substances are produced, and therefore indirectly determine how much strain is placed on the liver (3,4).
9. Consequences for the liver
The influence of the gut does not stop at fatty liver disease. Other liver conditions, such as alcohol-related liver cirrhosis, are also linked to the gut microbiome. While researchers are still investigating the exact mechanisms through which gut bacteria affect these diseases, one thing is clear: the gut and liver are in constant communication. The composition of your gut microbiome can have a significant impact on liver health – and, conversely, impaired liver function can also negatively affect gut health. What makes this particularly problematic is that the liver can endure stress for a long time without causing noticeable symptoms. Once serious structural damage has occurred, however, it is often difficult or impossible to reverse. This is why it is so important to take care of your liver early on, through a gut-friendly diet and a healthy lifestyle.
Using bioinformatic algorithms and our continuously growing database, the myBioma Microbiome Test Ultimate can provide indications of whether your microbial composition is supporting or burdening your liver health. You will also receive practical tips and simple recipe ideas to support the gut–liver axis. You can find more information about the test here: myBioma Microbiome Test Ultimate
10. How to support your liver
There is a lot you can do to keep your liver healthy and support your gut–liver axis (5,6,7):
- A balanced diet rich in colourful, antioxidant- and vitamin-rich fruits and vegetables, fibre-rich whole grains, legumes and healthy fats (keyword: Mediterranean diet)
- Regular physical activity and exercise, with sufficient recovery time
- Weight loss (if you are overweight)
- Prebiotic fibres such as pectin (for example in apples or citrus fruits) and resistant starch (for example in green bananas, cashew nuts, legumes, and cooked and cooled potatoes)
- Allowing breaks between meals (avoiding constant snacking) or trying intermittent fasting
- Sufficient sleep and relaxation
- Avoiding alcohol as well as highly processed, fatty and sugary foods
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Bitter compounds from plants such as artichoke or dandelion can stimulate digestion and bile flow, indirectly relieving the liver and improving fat digestion. They can be used as a supportive measure, but they do not replace a healthy diet and lifestyle.
Conclusion
When the intestinal barrier is weakened – for example due to dysbiosis – bacterial components can pass through the portal vein to the liver. If this burden persists, the immune system responds with inflammation and tissue damage may occur. In turn, an impaired liver negatively affects gut health and the microbiome, creating a vicious cycle.
Overall, the rule is simple: the healthier your gut, microbiome and lifestyle, the stronger and healthier your liver will be.
References
- Hsu, C. L., & Schnabl, B. (2023). The gut-liver axis and gut microbiota in health and liver disease. Nature Reviews. Microbiology, 21(11), 719–733.
- Tripathi A, Debelius J, Brenner DA, et al. The gut-liver axis and the intersection with the microbiome. Nat Rev Gastroenterol Hepatol. 2018;15(7):397-411.
- Bashiardes S, Shapiro H, Rozin S, Shibolet O, Elinav E. Non-alcoholic fatty liver and the gut microbiota. Mol Metab. 2016;5(9):782-94.
- Tilg, H., Adolph, T. E., & Trauner, M. (2022). Gut-liver axis: Pathophysiological concepts and clinical implications. Cell Metabolism, 34(11), 1700–1718.
- Roeb, E., Canbay, A., Bantel, H., Bojunga, et al (2022). Aktualisierte S2k-Leitlinie nicht-alkoholische Fettlebererkrankung der Deutschen Gesellschaft für Gastroenterologie, Verdauungs- und Stoffwechselkrankheiten (DGVS). Zeitschrift für Gastroenterologie, 60(09), 1346–1421.
- Ni, Y., Qian, L., Siliceo, S. L., et al (2023). Resistant starch decreases intrahepatic triglycerides in patients with NAFLD via gut microbiome alterations. Cell Metabolism, 35(9), 1530-1547.e8.
- (Promrat et al., 2010) Promrat, K., Kleiner, D. E., Niemeier, H. M., Jackvony, E., Kearns, M., Wands, J. R., Fava, J. L., & Wing, R. R. (2010). Randomized controlled trial testing the effects of weight loss on nonalcoholic steatohepatitis. Hepatology (Baltimore, Md.), 51(1), 121–129.
