The Effects of Conjugated Linoleic Acid Supplements on Biomarkers of Oxidative Stress in Human Studies: A Systematic Review and Meta-Analysis

Seyedeh-Masomeh  Derakhshandeh-Rishehri; Milad  Rajabzadeh-Dehkordi; Saeed  Ghobadi; Shiva  Faghih

doi:10.18502/jnfs.v9i1.14852

Seyedeh-Masomeh Derakhshandeh-Rishehri DONALD Study Center, Department of Nutritional Epidemiology, Institute of Nutrition and Food Science, University of Bonn, 44225 Dortmund, Germany
Milad Rajabzadeh-Dehkordi Department of Community Nutrition, School of Nutrition and Food Sciences, Shiraz University of Medical Sciences,Shiraz, Iran.
Saeed Ghobadi Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Melbourne, VIC, Australia j
Shiva Faghih Nutrition Research Center, Shiraz University of Medical Sciences, Shiraz, Iran

DOI: https://doi.org/10.18502/jnfs.v9i1.14852

Keywords: Conjugated linoleic acid; Oxidative stress; Malondialdehyde; Isoprostanes

Abstract

Background: Oxidative stress is the leading cause of chronic disorders. The aim of the present study is to assess the effects of conjugated linoleic acid (CLA) supplements on oxidative stress biomarkers in adults.

Methods: PubMed, Web of Science, Google Scholar, ProQuest, Scopus, and Embase were searched up to December 2020. All clinical trials that evaluated the effect of CLA on malondialdehyde (MDA), GSH-peroxidase (GPX), and 8-IsoprostanesF_2α(8-iso-PGF_2α) were included.

Results: Twelve eligible studies were included in the meta-analysis. A significant increase was observed in 8-iso-PGF_2α level (SMD=1.48 nmol/mmol of creatinine; 95% CI: 1.11 to 1.85) with low heterogeneity level (I²= 31.5%, and P=0.199). This effect was also significant in both subgroups of healthy and metabolic disorder individuals. Moreover, after Hartung-Knapp adjustment, the results remained significant. No significant changes were found in MDA (SMD=-0.34 µmol/l; 95% CI: -0.82 to 0.14) and GPX (SMD=0.31 U/gHb; 95% CI: -0.03 to 0.66) levels. However, after Hartung-Knapp adjustment, the results became significant for GPX level (SMD=0.31, 95% CI: 0.04 to 0.59).

Conclusion: CLA supplementation could significantly increase some markers of oxidative stress such as 8-iso-PGF_2α level and GPX level, without any significant effect on MDA level.