Coffee consumption has no effect on circulating markers of liver function but increases adiponectin concentrations: A systematic review and meta-analysis of randomized controlled trials

Nonalcoholic fatty liver disease has become the most common liver disorder worldwide, reaching a prevalence of 60% and 24% in patients with chronic liver disease and the general population, respectively. Liver function is often assessed using standard liver tests such as alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transferase, and alkaline phosphatase. Randomized controlled trials (RCTs) investigating the potential beneficial effects of coffee consumption on liver function are scarce and their results are inconclusive. Some clinical trials have shown a significant increase in adiponectin concentrations following coffee consumption; however, there are few studies in this field. Hence, the hypothesis of this meta-analysis of RCTs is that coffee consumption decreases blood markers of liver function and increases adiponectin concentrations. A systematic search was conducted in PubMed-MEDLINE, Scopus, Web of Science, ClinicalTrials.gov, and Google Scholar databases. Meta-analysis was performed using a random-effects model followed by sensitivity analysis. Meta-analysis of 14 RCTs, including a total of 897 subjects, showed that coffee consumption has no significant effect on alanine aminotransferase (weighted mean difference [WMD], -0.89 mg/mL; 95% CI, -2.90 to 1.12; P = .39), aspartate aminotransferase (WMD, -0.29 mg/mL; 95% CI, -1.25 to 0.66; P = .55), gamma-glutamyl transferase (WMD, .10 mg/mL; 95% CI, -3.94 to 4.15; P = .96), alkaline phosphatase (WMD, -4.60 mg/mL; 95% CI, -9.26 to 0.07; P = .05), and lactate dehydrogenase (WMD, -0.65 mg/mL; 95% CI, -10.80 to 9.49; P = .90). However, coffee administration significantly increased adiponectin concentrations (WMD, 1.19 mg/mL; 95% CI, 0.08-2.31; P = .04). The results of this meta-analysis of RCTs suggest that coffee consumption may improve liver dysfunction through the elevation of adiponectin levels; however, further clinical trials are needed to corroborate our findings.