The Surprising Link Between Your Gut Bacteria and Fatty Liver Disease

Perfectly healthy people who’ve sworn off alcohol are finding out they’ve developed fatty liver disease. The sneaky culprit behind this unexpected health twist? It might be your gut.

Photo: Hiroshi Watanabe/

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When you think “fatty liver,” you might think about alcohol. That’s because one of the primary forms of fatty liver disease has long been tied to excessive drinking, known as alcoholic fatty liver disease. But drinking isn’t the only culprit behind fatty liver disease. You can develop fat buildup in your liver without drinking a drop of alcohol.

Confused? You aren’t alone. Fatty liver disease is on the rise, with nonalcoholic fatty liver disease affecting about 1 in 3 Americans – and 25 percent of the world’s population. But it isn’t alcoholic fatty liver disease that’s so prevalent. It’s actually nonalcoholic fatty liver disease (NAFLD) that’s starting to appear everywhere. 

And while health factors like being obese, having high cholesterol and high blood pressure, or living with type 2 diabetes can all play a role in your risk for NAFLD, there’s another, lesser-known player: your gut. New research shows that your gut bacteria could play a pretty significant role in your odds of developing NAFLD.

Certain gut bacteria can actually produce alcohol

Recently, a man who had blood alcohol levels that equated to about 15 shots of whiskey caught the attention of researchers in Beijing, China. The man would seemingly suddenly become drunk, and he had a host of alcohol-related health woes – including nonalcoholic steatohepatitis (NASH), an advanced form of NAFLD. Yet this man wasn’t drinking any alcohol at all. He had no history of alcohol use, but he had symptoms similar to alcohol-induced fatty liver disease. 

When researchers started studying the man, they realized that his gut microbiome was home to a strain of bacteria that actually produced high levels of alcohol. Compared to healthy individuals, this bacteria was creating 4 to 6 times more alcohol. 

So, researchers thought there might be a link between that alcohol-producing bacteria – Klebsiella pneumoniae (HiAlc Kpn) – and the development of NAFLD. Might people diagnosed with NAFLD be experiencing liver fat deposits purely because of their gut bacteria? With a group of participants, the researchers examined what was happening in the guts of 43 individuals with NAFLD and 48 who did not have any liver health conditions.

Over time, bacteria might increase your odds of developing fatty liver disease

Over the course of the study, researchers compared the gut microbiota of those with NAFLD to those without it. They discovered that 60 percent of the participants who had NAFLD also had a strain of alcohol-producing HiAlc Kpn bacteria at either high or medium levels in their guts. 

In comparison, just 6 percent of those who didn’t have NAFLD had this same strain.

Because this particular strain of bacteria produces such a higher level of alcohol, it can be difficult for the body to cope. Your liver will struggle to break down all of the alcohol that’s being generated, which in turn can create the perfect conditions for fatty liver disease to develop. And even if you never take a sip of alcohol, your gut bacteria might be wreaking unexpected havoc on your liver.

The researchers then took their work one step further and tested their hypothesis in mice. When mice were infected with the HiAlc Kpn bacteria, they began to develop NAFLD within just one month. By the second month, those same mice were starting to show signs of long-term liver damage like liver scarring. 

But there was a bit of good news discovered: When researchers gave the mice an antibiotic to kill the HiAlc Kpn bacteria, their liver health improved. While more studies are needed to determine if antibiotics could be helpful for fatty liver disease, these results offer a promising glimpse into potential treatments.

What can you do if you have alcohol-producing gut bacteria?

First things first: There’s still a lot that’s unknown and yet to be discovered about this special strain of alcohol-producing gut bacteria. 

Currently, scientists aren’t certain where this particular bacteria strain comes from or why some of us have it while others don’t. The research study’s authors hypothesize that the HiAlc Kpn bacteria might enter the body through food or other environmental factors. Your particular gut environment might also play a role; some guts provide just the right combination of factors that this bacteria needs to grow and colonize. But genetics might also impact your odds of having the strain.

And since experts are still searching for the root cause behind this bacteria, we don’t yet know if potential avenues of treatment like the antibiotics tested in the study might become available. There’s still a lot you can do to both prevent and improve fatty liver disease with the knowledge we do have right now. Targeting the key factors that can contribute to fatty liver disease, like unhealthy eating habits or carrying excess weight, can potentially improve your liver’s health. Our guide to eating well for fatty liver disease can help you try a new approach.

You can also adjust your diet to keep your gut healthy and your microbiome balanced. It is possible to alter your gut bacteria – probiotics are the perfect way to introduce beneficial bacteria into your gut, and they can help counter “bad” bacteria. Similarly, prebiotics can encourage the growth of beneficial bacteria strains. To learn more about achieving good gut health, try our recommendations:

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