Background: Most studies to date on the cardiometabolic effects of eicosapentaenoic (EPA) and docosahexaenoic (DHA) in humans have used a mixture of the two fatty acids in different forms and proportions. The objective of this study was to compare the individual effects of EPA vs. DHA supplementation (as re-esterified triacylglycerol, 90% pure) on blood lipids and inflammatory markers in men and women at risk of cardiovascular diseases.

Methods: Using a double-blind, placebo-controlled crossover design, 48 men and 106 women with abdominal obesity were randomized to three treatment phases: 1-EPA (3g/d), 2-DHA (3g/d), 3-corn oil (placebo, 3g/d). Treatments had durations of 10 weeks each and were separated by an 8-week washout period. Blood lipids and inflammatory markers were measured before and after each treatment phase. Differences in study outcomes between treatments were assessed using the MIXED procedure for repeated measures with endpoint measures as primary outcomes. Potential confounders of the response to treatment, mainly obesity/body fat status, age, use of contraceptive agents (premenopausal women), menopausal status, treatment-specific baseline values and sequence of treatments were considered.

Results: EPA vs. placebo decreased plasma TG concentrations (−11.1±2.4%, p<0.001). DHA vs. placebo decreased diastolic blood pressure (DBP, −2.2±0.9%, p<0.001), TG (−18.1±2.5%, p<0.001), cholesterol(C)/HDL-C ratio (−2.5±1.4%, p=0.02), CRP (−8.4±5.0%, p=0.03), TNF-α (−13.7±5.2%, p=0.02) and IL-18 (−4.8±2.9%, p=0.01), and increased total C (+2.5±1.2%, p=0.001), HDL-C (+6.1±1.2%, p<0.001) and LDL-C (+5.0±1.9%, p<0.001). Changes in DBP (p=0.03), TG (p=0.02), total C (p<0.001), HDL-C (p<0.001), LDL-C (p=0.03), C/HDL-C ratio (p=0.02), IL-18 (p=0.007) and adiponectin (p<0.001) were greater with DHA than with EPA.

Conclusion: DHA is more effective than EPA in modulating blood lipids and inflammatory markers. Further studies are needed to determine the impact of a long term DHA supplementation on cardiovascular risk in men and women.