The effect of conjugated linoleic acid supplementation on oxidative stress markers: A systematic review and meta-analysis of randomized controlled trials.

BACKGROUND & AIMS Recent trial studies have found that conjugated linoleic acid (CLA) supplementation beneficially reduces oxidative stress markers but, there is no definitive consensus on this context. The present systematic review and meta-analysis aimed to investigate the effect of CLA supplementation on oxidative stress parameters. METHODS We searched PubMed, Web of Science, Scopus, Cochrane Library, and Google Scholar databases until September 2021 to identify randomized controlled trials (RCTs) assessing CLA supplementation effects on oxidative markers including malondialdehyde (MDA), 8-isoprostanesF2α (8-iso-PGF2α), and glutathione peroxidase (GPx). Summary estimates and corresponding 95% confidence intervals (CI) were derived via the DerSimonian and Laird method using a random-effects model. RESULTS A total of 11 RCTs were included. The obtained results show that CLA supplementation caused a significant decrease in MDA concentrations (Hedges's: -0.35; 95% CI: -0.70 to -0.01, P = 0.04, I2 = 62.1%, n = 7), and also significantly increased 8-iso-PGF2α levels (Hedges's: 1.45; 95% CI: 0.98 to 1.91, P˂0.001, I2 = 42.9%, n = 4). However, the results showed that supplementation with CLA did not significantly change the concentrations of GPx (Hedges's: 0.30; 95% CI: -0.04 to 0.64, P = 0.08, I2 = 0.0%, n = 3). CONCLUSION It seems this supplement can be used as a dietary supplement to improve oxidative stress parameters. However, further studies are required to demonstrate present results.