Flaxseed Oil Supplementation Augments Antioxidant Capacity and Alleviates Oxidative Stress: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

OBJECTIVE: Studies have reported controversial findings regarding the flaxseed oil effect on antioxidant status biomarkers. The present meta-analysis aimed to determine the impact of flaxseed oil on the serum level of biomarkers of oxidative stress. METHODS: A systematic search was conducted up to November 2020 on PubMed, Embase, Web of Science, Scopus, and Cochrane Central Library. Random-effects model was employed to perform meta-analysis. Subgroup analysis was carried out to determine the effect across different ranges of dosages and durations. RESULTS: Eight trials were included with a total sample size of 429 individuals with a mean age range of 25 to 70 years. The results indicated that flaxseed oil supplementation led to a significant decrease in malondialdehyde (MDA) levels (SMD: −0.52 μmol/L; 95% CI: −0.89, −0.15; P=0.006, I(2) = 71.3, P < 0.001) and increase in total antioxidant capacity (TAC) levels (WMD: 82.84 mmol/L; 95% CI: 19.80, 145.87; P=0.006, I(2) = 92.7, P < 0.001). No significant effect was observed on glutathione (GSH). CONCLUSION: Our findings revealed that flaxseed oil supplementation might play a beneficial role in the reinforcement of the antioxidant defense system and amelioration of oxidative stress in adults.