Does omega-3 PUFAs supplementation improve metabolic syndrome and related cardiovascular diseases? A systematic review and meta-analysis of randomized controlled trials

Abstract

Literature is inconsistent regarding the effects of omega-3 polyunsaturated fatty acids (omega-3 PUFAs) supplementation on patients with metabolic syndrome (MetS) and related cardiovascular diseases (CVDs). Therefore, the aim of this systematic review and meta-analysis is to summarize data from available randomized controlled trials (RCTs) on the effect of omega-3 PUFAs on lipid profiles, blood pressure, and inflammatory markers. We systematically searched PubMed, Embase, and Cochrane Library databases to identify the relevant RCTs until 1 November 2022. Weighed mean difference (WMD) was combined using a random-effects model. Standard methods were applied to assess publication bias, sensitivity analysis, and heterogeneity among included studies. A total of 48 RCTs involving 8,489 subjects met the inclusion criteria. The meta-analysis demonstrated that omega-3 PUFAs supplementation significantly reduced triglyceride (TG) (WMD: −18.18 mg/dl; 95% CI: −25.41, −10.95; p < 0.001), total cholesterol (TC) (WMD: −3.38 mg/dl; 95% CI: −5.97, −0.79; p = 0.01), systolic blood pressure (SBP) (WMD: −3.52 mmHg; 95% CI: −5.69, −1.35; p = 0.001), diastolic blood pressure (DBP) (WMD: −1.70 mmHg; 95% CI: −2.88, −0.51; p = 0.005), interleukin-6 (IL-6) (WMD: −0.64 pg/ml; 95% CI: −1.04, −0.25; p = 0.001), tumor necrosis factor-α (TNF-α) (WMD: −0.58 pg/ml; 95% CI: −0.96, −0.19; p = 0.004), C-reactive protein (CRP) (WMD: −0.32 mg/l; 95% CI: −0.50, −0.14; p < 0.001), and interleukin-1 (IL-1) (WMD: −242.95 pg/ml; 95% CI: −299.40, −186.50; p < 0.001), and significantly increased in high-density lipoprotein (HDL) (WMD: 0.99 mg/dl; 95% CI: 0.18, 1.80; p = 0.02). However, low-density lipoprotein (LDL), monocyte chemoattractant protein-1 (MCP-1), intracellular adhesion molecule-1 (ICAM-1), and soluble endothelial selectin (sE-selectin) were not affected. In subgroup analyses, a more beneficial effect on overall health was observed when the dose was ≤ 2 g/day; Omega-3 PUFAs had a stronger anti-inflammatory effect in patients with CVDs, particularly heart failure; Supplementation with omega-3 PUFAs was more effective in improving blood pressure in MetS patients and blood lipids in CVDs patients, respectively. Meta-regression analysis showed a linear relationship between the duration of omega-3 PUFAs and changes in TG (p = 0.023), IL-6 (p = 0.008), TNF-α (p = 0.005), and CRP (p = 0.025). Supplementation of omega-3 PUFAs had a favorable effect on improving TG, TC, HDL, SBP, DBP, IL-6, TNF-α, CRP, and IL-1 levels, yet did not affect LDL, MCP-1, ICAM-1, and sE-selectin among patients with MetS and related CVDs.

Keywords:

• Omega-3 PUFAs
• metabolic syndrome
• cardiovascular diseases
• meta-analysis
• randomized controlled trials

Authors’ contributions

X.W. and Z.H. contributed to the conception and design of this manuscript. Y.W., Y.W., S.Q., Y. S., L.X., L.Y., W.Z., Z.F., G.W., W.W., and Q.J. contributed to the manuscript drafting, literature search, data interpretation, and statistical analyses. All authors approved the final manuscript for submission.

Disclosure statement

The authors declare no conflict of interest.

Additional information

Funding

This work was supported by the National Key Research and Development Project of China (2021YFD2100303).