Effects of Carotenoid Supplementation on Exercise-Induced Oxidative Stress: A Systematic Review and Meta-Analysis of Randomized Clinical Trials.

Objective: This study aims to investigate the potential effects of carotenoid supplementation on mitigating exercise-induced oxidative stress and to provide guidance for future research.

Methods: We conducted a systematic review and meta-analysis using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched multiple databases from inception to August 2024 for randomized clinical trials investigating the effects of carotenoid supplementation on biomarkers of oxidative stress, inflammatory markers, antioxidant levels, and metabolic parameters in the context of exercise-induced oxidative stress. The search terms included "carotenoids," "supplementation," "exercise," "oxidative stress," "inflammation," "antioxidants," "metabolic parameters," and their synonyms. Two reviewers independently extracted study data, with disagreements resolved by a third reviewer. Quality was assessed by the Cochrane risk-of-bias method. Random and fixed effects models were used for the analysis of standard mean differences (SMD) or weighted mean differences (MDs) with 95% confidence intervals (CI).

Results: A total of 12 studies were included in the final analysis. Carotenoid supplementation led to significant effects in assessing oxidative stress induced by exercise (overall oxidative stress: SMD = -0.55, 95% CI [-1.04, -0.06]; malondialdehyde: MD = -0.05, 95% CI [-0.09,-0.02]; total antioxidant capacity: MD = 0.03, 95% CI [0.02, 0.03]; 8-isoprostane: MD = -35.70, 95% CI [-59.32, -12.09]; lipid peroxide: SMD = -1.07, 95% CI [-1.94, -0.20]; and nitric oxide: MD = -8.07, 95% CI [-12.54,-3.59]), inflammatory markers (inflammatory levels: SMD = 1.63, 95% CI [0.81, 2.46]; interleukin levels: SMD = 1.54, 95% CI [0.69, 2.40]; and C-reactive protein: MD = 4.56, 95% CI [0.97, 8.14]), antioxidant levels (SMD = 0.84, 95% CI [0.14, 1.53]), and metabolic parameters (energy expenditure: SMD = -0.52, 95% CI [-0.78, -0.26]; p < .05).

Conclusion: Carotenoid supplementation appears to attenuate exercise-induced oxidative stress and the inflammatory response and improve antioxidant levels and metabolic capabilities. However, these results may be influenced by participant variability or methodological differences. Further research with larger sample sizes, longer supplementation periods, higher doses, and carotenoid bioavailability is needed to confirm these findings.