Ethnicity matters: A Systematic Review and Meta-Analysis of the Non-Linear Relationship Between Alcohol Consumption and Prevalence and Incidence of Hepatic Steatosis

•The relationship between low alcohol consumption (< 20 g/day) and hepatic steatosis was consistently beneficial in Japan.•In Japanese men, alcohol consumption up to 80 g/day was inversely associated with hepatic steatosis.•In Japanese women, the relationship was J-shaped and turned detrimental beyond average alcohol consumption of 20 g/day.•There was marked heterogeneity across studies in countries other than Japan with no clear relationship.•More high-quality epidemiological and clinical studies are necessary to confirm these relationships.Fatty liver (steatosis) is a common disease worldwide. We systematically examined the influence of alcohol consumption on fatty liver using published observational studies. In total, 99370 participants and 25662 cases of fatty liver from 18 studies were included. In comparison to non-drinkers, low alcohol consumption (2–3 drinks per day) showed a beneficial effect (about 25% reduction) in Japan, well adjusted for the most important risk factor for fatty liver (excess body weight). There was no clear relationship in other countries. More research in diverse ethnic populations is needed to further clarify the role of alcohol consumption.

BackgroundFatty liver (hepatic steatosis) is one of the most common diseases globally, with increasing prevalence. The role of alcohol consumption in the development of hepatic steatosis has not been systematically examined.MethodsWe searched Medline, Embase, and ProQuest Dissertations & Theses Global for original data on the relationship between alcohol consumption and hepatic steatosis measured by non-invasive imagery, excluding studies conducted in participants < 18 years, or subgroups related to viral and drug-induced liver disease. We identified 18 articles reporting adjusted data (Japan = 11, other high-income countries = 7). Random-effect categorical meta-analyses (< 20 g/day pure alcohol consumption vs non-drinkers) and dose-response meta-analyses for the whole range of alcohol consumption were conducted.ResultsIn total, 99,370 participants and 25,662 cases of hepatic steatosis were included. In Japan, low alcohol consumption was consistently associated with substantially reduced incidence and prevalence of hepatic steatosis compared to non-drinkers (RR for < 20 g pure alcohol/day = 0.75, 95% CI: 0.71–0.79, I2 = 0%). No overall association was found in other countries (RR = 1.05, 95% CI: 0.86–1.30, I2 = 84%). Dose-response analyses in Japan (up to 80 g/day) showed an inverse relationship in men and a J-shape in women.ConclusionsAlcohol consumption showed a complex association with hepatic steatosis with substantial differences by ethnicity and sex. Low alcohol consumption was beneficial in Japan with good epidemiological evidence, whereas there was no association in other countries. However, heterogeneity was large in countries other than Japan. More and higher quality research in diverse ethnic populations is needed to further clarify this relationship.