Effects of Omega-3 Fatty Acids Supplementation on Serum Lipid Profile and Blood Pressure in Patients with Metabolic Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Systematic review and meta-analysis of randomized controlled trials in adults with metabolic syndrome from multiple countries. The review compared omega-3 fatty acid supplementation with control conditions and pooled effects on serum lipids and blood pressure.

Oral omega-3 PUFA supplementation was evaluated across randomized trials, using fish oil, flaxseed oil, or n-3 PUFA formulations. Regimens ranged from 1 g/day fish oil (180 mg EPA and 120 mg DHA) to 25 mL/day flaxseed oil providing about 10.25 mL alpha-linolenic acid (ALA), with treatment durations from 7 weeks to 6 months.

Omega-3 PUFA supplementation reduced triglycerides and lowered both systolic and diastolic blood pressure, but it did not significantly change total cholesterol, LDL-C, or HDL-C. Pooled effects favored supplementation for triglycerides (SMD = −0.39; 95% CI: −0.59 to −0.18; I2 = 17.2%), systolic blood pressure (SMD = −0.54; 95% CI: −0.86 to −0.22; I2 = 48.6%), and diastolic blood pressure (SMD = −0.56; 95% CI: −0.79 to −0.33; I2 = 14.0%). No significant effects were seen for total cholesterol (SMD = −0.02; 95% CI: −0.22 to 0.18), LDL-C (SMD = 0.18; 95% CI: −0.18 to 0.53), or HDL-C (SMD = 0.02; 95% CI: −0.21 to 0.25). Longer interventions of more than 12 weeks appeared to produce greater triglyceride reductions, and the review did not find clear differences between EPA, DHA, and ALA.

The evidence base was relatively small and included heterogeneous omega-3 formulations, doses, and treatment durations. The review could not determine whether EPA, DHA, or ALA differed in effect, and some outcomes showed moderate heterogeneity, particularly systolic blood pressure and LDL-C. Short follow-up in several trials limits inference about longer-term effects.