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You may be a fan of homebrewed craft beers, but this is probably not what you had in mind. Some unlucky people are brewing alcohol in their own intestines, leading to nausea, mild drunkenness, and worse: liver problems.
For the first time, researchers in China have isolated a specific gut bacteria called Klebsiella pneumoniae that appears to contribute to this problem. According to a study published Sept. 19 in the journal Cell Metabolism, this problem is far more common than researchers once thought, contributing to a large prevalence of non-alcoholic fatty liver disease (NAFLD) and its more serious progression, nonalcoholic steatohepatitis (NASH).
"These results suggest that at least in some cases of NAFLD an alteration in the gut microbiome drives the condition due to excess endogenous alcohol production," the study states.
"Auto-brewery" syndrome is a disease in which the gut microbiome produces its own alcohol, fermenting sugars and carbohydrates in the intestines, which then absorb into the body in the same way ethyl alcohol from the bottle does. Scientists once thought this was rare and linked to an overproduction of gut yeast. But antifungals used to kill off yeast seem to have no effect on the condition.
In his first attempt to find a bacterial culprit in NAFLD and NASH, researcher Jing Yuan used mice bred in sterile conditions with no microbiome of their own. When Yuan's team introduced Klebsiella to these mice, most of them developed NAFLD over the course of several weeks, according to the study.
The most recent research tested the Klebsiella hypothesis in a cohort of Chinese patients with NASH and NAFLD. Results showed 60% had elevated levels of Klebsiella in stool samples, and that Klebsiella continued to manufacture alcohol when cultured in the lab from stool samples.
Researchers say NAFLD and NASH have multiple causes, so not all cases can be ascribed to a Klebsiella overgrowth. But it may be responsible for a significant number of cases of these liver conditions.
NAFLD numbers correlate with the obesity epidemic; being significantly overweight can cause harmful fat deposits in your liver. The NIH cites a paper showing 90% of obese people who signed up for bariatric surgery had NAFLD.
If you're overweight or have diabetes, you and your doctor should monitor your liver markers for warning signs of NAFLD and NASH, writes Jay W. Marks, MD, a gastroenterologist and MedicineNet's medical and pharmacy editor.
"Fatty liver disease rarely causes symptoms until the liver disease is far advanced," Dr. Marks says. "Fatty liver usually is found or suspected when abnormal liver tests are found on routine blood testing, fat is seen ultrasonographically when ultrasonography of the abdomen is performed for other reasons, for example, the diagnosis of gallstones, or (infrequently) when the liver is enlarged on physical examination of a patient."
When the liver disease is far advanced (cirrhosis), signs and symptoms of cirrhosis predominate, Dr. Marks says. These include:
- Excessive bleeding due to the inability of the liver to make blood-clotting proteins
- Jaundice due to the inability of the liver to eliminate bilirubin from the blood
- Gastrointestinal bleeding due to portal hypertension that increases the pressure in intestinal blood vessels
- Fluid accumulation due to portal hypertension that causes fluid to leak from blood vessels and the inability of the liver to make the major blood protein, albumin
- Mental changes (encephalopathy) due to the liver's inability to eliminate chemicals from the body that are toxic to the brain
- Liver cancer
Read MedicineNet's full article on liver disease for more information.