Gut Bacteria That Brew Booze May Cause Liver Damage

A research group in China has found that alcohol-producing gut bacteria could cause liver damage even in people who don’t drink.

AsianScientist (Oct. 14, 2019) – Non-drinkers of alcohol contract non-alcoholic fatty liver disease (NAFLD) due to a particular microbe in their guts, say scientists in China. They reported their findings in Cell Metabolism.

About a quarter of the adult population globally is affected by NAFLD, which is characterized by the build-up of fat in the liver that eventually impairs liver function. The precise cause of NAFLD was obscure, but scientists led by Professor Yuan Jing at the Capital Institute of Pediatrics, China, have found that it is associated with bacteria that reside in the gut.

Yuan and her team discovered the link between gut bacteria and NAFLD when they encountered a patient with severe liver damage and a rare condition called auto-brewery syndrome (ABS). Patients with ABS would become drunk after eating alcohol-free and high-sugar food. The condition has been associated with yeast infection, which can produce alcohol in the gut and lead to intoxication.

Analyzing the patient’s fecal samples, the team found he had several strains of the bacteria Klebsiella pneumoniae in his gut that produced high levels of alcohol. K. pneumoniae is a common type of commensal gut bacteria, but the strains isolated from the patient’s gut can generate about 4-6 times more alcohol than strains found in healthy people.

Moreover, the team sampled the gut microbiota from 43 NAFLD patients and 48 healthy people. They discovered that about 60 percent of NAFLD patients had K. pneumoniae strains that produced medium-to-high levels of alcohol in their gut. Only six percent of healthy controls carry these strains.

To investigate if K. pneumoniae would cause fatty liver, researchers fed germ-free mice with high-alcohol-producing K. pneumoniae isolated from the ABS patient for three months. These mice started to develop fatty liver after the first month. By the second month, their livers showed signs of scarring, which means long-term liver damage had occurred. The progression of liver disease in these mice was comparable to that of mice fed with alcohol. When the team gave bacteria-fed mice with an antibiotic that killed K. pneumoniae, the condition of the mice was reversed.

“NAFLD is a heterogenous disease and may have many causes,” Yuan said. “Our study shows that K. pneumoniae is very likely to be one of them. These bacteria damage your liver just like alcohol, except you don’t have a choice [in the matter].”

It remains unknown why some people have high-alcohol-producing K. pneumonia strain in their gut while others don’t. Nonetheless, the researchers noted that their findings could help diagnose and treat bacteria-related NAFLD. Because K. pneumonia produce alcohol using sugar, patients who carry these bacteria would have a detectable amount of alcohol in their blood after drinking a simple glucose solution.

“In the early stages, fatty liver disease is reversible. If we can identify the cause sooner, we could treat and even prevent liver damage,” Yuan said.

The article can be found at: Yuan et al. (2019) Fatty Liver Disease Caused by High-Alcohol-Producing Klebsiella pneumoniae.


Source: Cell Press; Photo: Pexels.
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