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Alcohol-Producing Gut Bacteria May Damage Liver

NON-ALCOHOLIC fatty liver disease (NAFLD) is characterised by the build-up of fat in the liver, arising from factors other than alcohol. The disease affects roughly 25% of the global adult population, yet the cause remains unknown. A recent study conducted at the Capital Institute of Pediatrics, Beijing, China, has linked NAFLD to gut bacteria that produce vast amounts of alcohol in the body.

Jing Yuan, researcher at Capital Institute of Pediatrics, noted that “we were surprised that bacteria can produce so much alcohol.” The link between NAFLD and gut bacteria was uncovered by Dr Yuan and her team after they encountered a patient with severe liver damage and a rare condition called auto-brewery syndrome (ABS). These ABS patients would become drunk after eating alcohol-free and high-sugar food. The condition is associated with yeast infection resulting in alcohol production in the gut and intoxication; however, the patient’s yeast test results were negative and anti-yeast medicine proved ineffective, prompting Dr Yuan to suspect that the disease was caused by something else.

After analysing the faeces of the patient, strains of the bacteria Klebsiella pneumonia were discovered in the patient’s gut which produced high levels of alcohol. Additionally, the team tested gut microbiota from 43 NAFLD patients and 48 healthy patients. Results showed that 60% of the NAFLD patients carried strains of high and medium-alcohol-producing K. pneumonia compared to 6% in the healthy controls. Further results showed that K. pneumonia fed to germ-free mice displayed fatty liver, liver damage, and a disease progression similar to mice fed with alcohol for 2 months.

It remains unknown why some people have high-alcohol-producing K. pneumonia strains in their gut while others don’t. Co-researcher Dr Liu, University of Chinese Academy of Sciences, Beijing, China, believes that some may have a gut environment more suitable for the growth of K. pneumonia because of their genetics or that the bacteria enter people’s bodies via some carriers from the environment. Because K. pneumonia produce alcohol using sugar, patients carrying the disease would have a detectable amount of alcohol in their blood after drinking a glucose solution; therefore, moving forward, the study findings could diagnose and treat bacteria related NAFLD.