Letter: association between moderate alcohol consumption and non‐alcoholic fatty liver disease

We read with great interest the study by Wong et al.1 on the association between non-alcoholic fatty liver disease (NAFLD) and endotoxaemia. The main finding in that article was that endotoxin markers are related to NAFLD in the general population, but not with non-alcoholic steatohepatitis activity or liver fibrosis. Noticeably, people with modest alcohol consumption had lower serum endotoxin levels compared with those of nondrinkers. The authors suggested that reduced endotoxaemia might partly explain the lower risk of NAFLD in subjects with modest alcohol drinking. Modest alcohol drinking has been shown to ameliorate the risk of NAFLD in several epidemiological studies.2-4 The improvement in insulin resistance has been considered to be responsible for the lower risk of NAFLD in moderate drinkers.5 However, controversy exists over the effect of moderate alcohol consumption on subjects with a histological diagnosis of NAFLD. Contrary to positive results, some studies have reported that moderate alcohol consumption is related with progression of hepatic fibrosis or elevated serum alanine aminotransferase activity in patients with NAFLD.6, 7 Moreover, experimental studies have shown the adverse effect of alcohol intake on underlying non-alcoholic steatohepatitis.8, 9 Although moderate alcohol consumption might have protective effects in subjects without fatty liver, the beneficial effects of moderate alcohol drinking need to be confirmed in subjects with underlying fatty liver. The results of Wong et al. are promising for the explanation of the protective effect of moderate alcohol consumption. However, these data should be interpreted with caution, as the authors did not take into account alcohol drinking status when analysing factors associated with intrahepatic triglyceride content. Moreover, an analysis stratified by fatty liver status could produce a different outcome in terms of the comparison of endotoxic markers between nondrinkers and modest drinkers. We believe that the study by Wong et al. provides evidence of the potential beneficial effect of modest alcohol consumption on NAFLD via alterations in serum endotoxin levels. Declaration of personal and funding interests: None.