The Effects of Modest Alcohol Consumption on Non-alcoholic Fatty Liver Disease: A Systematic Review and Meta-Analysis

Abstract

Background and Objective: There is no consensus regarding modest alcohol consumption in patients with non-alcoholic fatty liver disease (NAFLD) due to conflicting results. The aim of this meta-analysis was to examine the effects of modest alcohol consumption on histological severity, histological course, hepatocellular carcinoma, and long-term clinical outcomes in NAFLD patients.Methods: We searched MEDLINE and EMBASE databases from inception to October 2020 for studies evaluating the effects of modest alcohol consumption among patients with NAFLD. A random-effects meta-analysis using pooled odds ratio (OR) and hazard ratio (HR) was calculated with 95% confidence interval (CI). Study quality was assessed with the Newcastle-Ottawa Scale.Results: Fourteen cross-sectional or cohort studies with aggregate data on 14,435 patients were included in the analysis. Modest alcohol consumption resulted in lower risks for steatohepatitis (OR 0.59; 95% CI 0.45–0.78; I2 = 12%) and advanced fibrosis (OR 0.59, 95% CI 0.36–0.95; I2 = 75%). Histological follow-up data showed that modest alcohol use was associated significantly with less steatohepatitis resolution but not with fibrosis progression. The HR for developing hepatocellular carcinoma was 3.77 (95% CI 1.75–8.15; I2 = 0%). NAFLD patients with modest alcohol intake had a lower mortality risk than lifelong abstainers (HR 0.85; 95% CI 0.75–0.95; I2 = 64%).Conclusion: This meta-analysis suggests that medical advice for modest alcohol drinking should be made cautiously in caring for an individual patient based on the clinical context. Practically, patients with steatohepatitis or advanced fibrosis should avoid alcohol use, whereas patients with low fibrosis risk may be allowed for modest and safe drinking.

Lifestyle and metabolic factors for nonalcoholic fatty liver disease: Mendelian randomization study

“…A threeyear longitudinal study with 4 waves' repeated measurements including up to 3773 Japanese adults found that light to moderate alcohol consumption was associated with a reduced risk of NAFLD in both sexes [30]. This inverse association was also identified in a recent meta-analysis of 14 observational studies [31]. However, moderate alcohol use compared to nondrinking was associated with less improvement in steatosis and level of aspartate transaminase in 285 NAFLD patients after a mean follow-up period of 47 months [9].…”

Alcohol consumption and metabolic syndrome: Clinical and epidemiological impact on liver disease

“…They found that moderate alcohol intake was associated with a pooled HR of 3.77 for developing HCC (Figure 4). 94 Kimura et al also showed that moderate drinking appeared to be a risk factor for HCC in patients with NAFLD, particularly those with advanced fibrosis. 100 A prospective study in a general population cohort based in the US showed that modest alcohol consumption was associated with a significant reduction in all-cause mortality.…”

“…93 A more recent meta-analysis also suggested that moderate alcohol consumption was associated with reduced odds of developing NASH and advanced fibrosis. 94 However, most of these studies employed observational cross-sectional designs.…”

The effects of moderate alcohol consumption on non-alcoholic fatty liver disease

“…Although alcohol is a carcinogen with a well-known dose-risk relationship, 32,33 meta-analyses based on many previous studies have published results that moderate alcohol consumption showed a protective effect against NAFLD (Table 2). [26][27][28]34 Interestingly, Sookoian et al suggest that moderate alcohol consumption is associated with a significant protective effect against NAFLD (Table 2). Body mass index (BMI) was not a statistically significant confounding factor in meta-regression analysis (slope=0.01, p<0.44) but moderate alcohol consumption was more protective in women than men (53% in women, 30% in men).…”

“…45 A meta-analysis by Wongtrakul et al, narrowed down the analysis target to NAFLD patients with moderate alcohol consumption only, suggested significant HR (3.77, 95% CI, 1.75-8.15; I 2 =0%) for developing HCC. 34 There are pitfalls to consider before accepting the conflicting research results discussed above.…”