EICOSAPENTAENOIC ACID IS PRIMARILY RESPONSIBLE FOR HYPOTRIGLYCERIDEMIC EFFECT OF FISH-OIL IN HUMANS

The aim of this study was to determine whether eicosapentaenoic acid ( EPA) or docosahexaenoic acid (DHA), or both, were responsible for the triglyceride (TG)-lowering effects of fish oil. EPA (91% pure) and DHA (83% pure), a fish oil concentrate (FOG; 41% EPA and 23% DHA) and an olive oil (OO) placebo (all ethyl esters) were tested. A total of 49 n ormolipidemic subjects participated. Each subject was given placebo fo r 2-3 wk and one of the n-3 supplements for 3 wk in randomized, blinde d trials. The target n-3 fatty acid (FA) intake was 3 g/day in all stu dies. Blood samples were drawn twice at the end of each supplementatio n phase and analyzed for lipids, lipoproteins, and phospholipid FA com position. In all groups, the phospholipid FA composition changed to re flect the n-3 FA given. On DHA supplementation, EPA levels increased t o a small but significant extent, suggesting that some retroconversion may have occurred. EPA supplementation did not raise DHA levels, howe ver. FOC and EPA produced significant decreases in both TC and very lo w density lipoprotein (VLDL) cholesterol (C) levels (P < 0.01) and inc reases in low density lipoprotein (LDL) cholesterol levels (P < 0.05). DHA supplementation did not affect cholesterol, triglyceride, VLDL, L DL, or high density lipoprotein (HDL) levels, but it did cause a signi ficant increase in the HDL(2)/HDL(3) cholesterol ratio. We conclude th at EPA appears to be primarily responsible for TG-lowering (and LDL-C raising) effects of fish oil.