At first glance, it sounds like an ambitious project -develop a gut microbiome that produces alcohol. It could obviate the need for “Duff” beer (Duff Beer – Wikipedia, the free encyclopedia). Yet, a recent article has found that an altered microbiome with increased endogenous alcohol already exists and it is associated with nonalcoholic steatohepatitis (NASH) (Hepatology 2013; 57: 601-609).
In this study, the authors examined three pediatric populations: a healthy control group (n=16), obese group (n=25), and NASH group (n=22). All NASH patients had undergone liver biopsy and met Kleiner’s criteria; in contrast, the obese group had normal LFTs.
Key study findings:
1. The microbiome from the obese and NASH patients were similar but had some striking differences compared with the control group patients (pie chart –Figure 2):
- Bacteroidetes (including Bacteroides): 28.65% in healthy controls, 50.28% in obese, and 49.11% in NASH
- Firmicutes (including Blautia and Faecalibacterium): 66.78% in healthy controls, 42.62% in obese, and 42.39% in NASH
- Proteobacteria (including Escherichia): 0.87% in healthy controls, 3.13% in obese, and 6.03% in NASH
2. Elevated serum ethanol concentrations only in NASH population: ~26 μM in both control and obese groups compared with ~35 μM in NASH patients.
Under normal conditions, endogenous alcohol is produced in the human body and the intestinal microflora are the major source. This gut-produced alcohol is quickly metabolized by the liver. Due to similar histology between NASH patients and patients with alcoholic liver disease, it has been hypothesized that NASH patients may have elevated blood alcohol. This study adds further evidence to this hypothesis and provides a potential mechanism; namely, increased bacteria like Escherichia and Bacteroides can increase endogenously-produced alcohol.
Will efforts to revert the microbiome to normal have therapeutic effects on NASH? This important question will need to be addressed given the growing problem of fatty liver disease.
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