Curcumin supplementation effect on liver enzymes in patients with nonalcoholic fatty liver disease: a GRADE-assessed systematic review and dose-response meta-analysis of randomized controlled trials

Abstract

CONTEXT: Clinical evidence from investigations of the effects of curcumin on liver enzymes in patients with nonalcoholic fatty liver disease (NAFLD) have led to inconsistent results. OBJECTIVE: The aim of this systematic review and meta-analysis was to investigate the overall effects of curcumin and curcumin plus piperine supplementation on liver enzymes such as alanine aminotransferase (ALT), alkaline phosphatase (ALP), and aspartate aminotransferase (AST) in patients with NAFLD. DATA SOURCES: The Scopus, Web of Science, PubMed, and Cochrane Library databases were searched from inception through July 2023, using search terms representing NAFLD and liver enzymes. Articles were screened independently by 2 researchers based on PICOS inclusion criteria. DATA EXTRACTION: The following data were extracted: first author's name, study location, year of publication, mean age, study duration, study design, participants' sex, number of participants in each group, dose of curcumin supplementation, and ALT, ALP, and AST concentrations. Risk of bias was assessed using the Cochrane Collaboration's modified risk-of-bias tool. DATA ANALYSIS: Fixed- or random-effects meta-analysis was performed to estimate the effects of curcumin on liver enzymes, considering heterogeneity across studies. The I2 and Cochran's Q tests were used to assess heterogeneity between studies. RESULTS: Overall, 15 randomized controlled trials comprising 905 participants were eligible for this meta-analysis. Curcumin supplementation significantly reduced ALT (weighted mean difference WMD, -4.10, 95%CI, -7.16 to -1.04) and AST (WMD, -3.27; 95%CI, -5.16 to -1.39), but not ALP (WMD, -0.49; 95%CI, -1.79 to 0.82). Curcumin plus piperine supplementation had no significant effect on ALT (WMD, -3.79; 95%CI, -13.30 to 5.72), and AST (WMD, -1.1; 95%CI, -3.32 to 1.09). CONCLUSIONS: Curcumin supplementation improved AST and ALT levels compared with the control group. However, better-designed randomized controlled trials with larger sample sizes and of higher quality are needed to assess the effects of curcumin on ALP. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration no. CRD42023448231.