Alcohol consumption and risk of metabolic syndrome: A meta-analysis of prospective studies

Background & aims: Epidemiological evidence suggests that alcohol consumption is related to the incidence and development of metabolic syndrome. However, data on this issue are unstable and controversial. We conducted a meta-analysis to provide a quantitative assessment of the association between alcohol intake and risk of metabolic syndrome. Methods: We searched the Pubmed and Embase databases up to May 2013 to identify prospective cohort studies related to alcohol consumption and metabolic syndrome. Summary effect estimates with 95% confidence intervals (CI) were derived using a fixed or random effects model, depending on the heterogeneity of the included studies. Results: Six prospective studies involving 28,862 participants with 3305 cases of metabolic syndrome were included in the meta-analysis. On the basis of the Newcastle Ottawa Scale system, 83.3% of the studies were identified as relatively high-quality. In our primary analysis, compared with nondrinker, very light drinker was associated with decreased risk of metabolic syndrome [pooled relative risk (RR) 0.86, 95% CI: 0.75-0.99, fixed-effect model] while heavy drinker was associated with increased risk of metabolic syndrome (pooled RR 1.84, 95% CI: 1.34-2.52, fixed-effect model). No indications of heterogeneity and publication bias were found in these two groups. Estimates of total effects were generally consistent in the sensitivity and stratification analyses. Conclusion: The present meta-analysis of prospective studies suggested that heavy alcohol consumption might be associated with an increased risk of metabolic syndrome while very light alcohol consumption seemed to be associated with a reduced risk of metabolic syndrome.