Meta-analysis: The impact of light-to-moderate alcohol consumption on progressive non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is defined as fatty liver disease in the absence of heavy alcohol consumption. However, the impact of light-to-moderate alcohol consumption on progressive NAFLD and on mortality is presently unclear.

Medline, Embase, OATD and OpenGrey were systematically searched up to November 2022 for relevant cross-sectional, case-control and cohort studies. The study outcomes were progressive NAFLD-steatohepatitis (NASH), fibrosis, cirrhosis, hepatocellular carcinoma (HCC) and mortality. The entire review process was performed by two independent reviewers. A narrative synthesis was performed for all outcomes, while meta-analyses, subgroup analyses and publication bias assessment were performed depending on the number of articles.

After study selection, 32 articles were included. Cohort studies reported that moderate alcohol intake increased the risk for advanced fibrosis (pooled OR 1.56; 95% CI 1.08-2.26 and HR 1.39; 95% CI 1.22-1.57), which was not observed in cross-sectional studies. Alcohol use also increased the risk of developing liver cirrhosis and HCC, but seemed to lower the risk of steatohepatitis. Light alcohol consumption protected against all-cause mortality, an effect not observed in NAFLD patients with moderate intake.

There is wide heterogeneity in studies on the impact of alcohol on progressive NAFLD. Nevertheless, cohort studies reported a significant harmful effect of moderate alcohol consumption on the occurrence of advanced fibrosis. Further research is needed to make valid recommendations with regard to alcohol consumption in patients with NAFLD.