Background: Previous research reported inconsistent findings regarding the effects of conjugated linoleic acid (CLA) supplementation on liver enzymes. This systematic review and meta-analysis was conducted to summarize data from available randomized clinical trials (RCTs) on the effect of CLA supplementation on alanine aminotransferase (ALT), aspartate aminotransferase (AST) and malondialdehyde (MDA) in adults.
Methods: Google Scholar, PubMed, Web of Science, Scopus, and the Cochrane databases were investigated to identify relevant articles up to July 2022. The weighted mean differences (WMD) and 95 % confidence intervals (CI) were calculated via a random-effects model to evaluate the effect size. Between studies, heterogeneity was evaluated by the Cochran's Q test and I2.
Results: 22 RCTs with 26 effect sizes were included. The effect size for ALT (IU/L), AST (IU/L), and MDA (µmol/L) were 19, 19 and 6 respectively. The pooled analysis demonstrated CLA decreases MDA (p = 0.003). However, ALT and AST levels did not change after CLA supplementation compared with control group.
Conclusion: CLA supplementation may significantly reduce MDA levels as a marker of oxidative stress. However, supplementing with CLA failed to alter ALT and AST.
Keywords: Conjugated linoleic acid; Liver enzyme; Malondialdehyde; Meta-analysis; Systematic review.
Published by Elsevier Ltd.