Effects of dietary eicosapentaenoic acid and docosahexaenoic acid supplementation on metabolic syndrome: A systematic review and meta-analysis of data from 33 randomized controlled trials

Background & aims: Previous randomized controlled trials (RCTs) have compared the effects of pure preparations of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in reducing metabolic syndrome (MetS) risk factors, but the results were inconsistent. The present study aimed to clarify whether EPA and DHA have differential effects on MetS features in humans. Methods: A systematic literature search was conducted in CNKI, PubMed, Embase and Scopus updated to February 2021. The mean changes in the characteristics of MetS were calculated as weighted mean differences by using a random-effects model. Thirty-three RCTs were included. Results: The results showed that both EPA and DHA were effective at lowering serum triglycerides (TG) levels. EPA supplementation decreased the serum levels of total cholesterol (TC) (WMD = −0.24 mmol/L; 95% CI, −0.43, −0.05 mmol/L), TG (WMD = −0.77 mmol/L; 95% CI, −1.54, −0.00 mmol/L) and low density lipoprotein-cholesterol (LDL-C) (WMD = −0.13 mmol/L; 95% CI, −0.25, −0.01 mmol/L), while DHA increased the serum levels of TC (WMD = 0.14 mmol/L; 95% CI, 0.03, 0.25 mmol/L), LDL-C (WMD = 0.26 mmol/L; 95% CI, 0.15, 0.38 mmol/L) and high density lipoprotein-cholesterol (HDL-C) (WMD = 0.07 mmol/L; 95% CI, 0.04, 0.09 mmol/L). Moreover, DHA increased the serum levels of insulin compared with EPA, especially in subgroups whose mean age was <60 years (0.43 mU/L; 95% CI: 0.04, 0.81 mU/L) and duration of DHA supplementation < 3 months (0.39 mU/L; 95% CI: 0.01, 0.77 mU/L). Conclusions: The present meta-analysis provides evidence that EPA and DHA have different effects on risk factors of MetS.