Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/10/2007
Publication Date: 10/10/2007
Citation: Kelley, D.S., Siegel, D., Vemuri, M., Chung, G.H., Mackey, B.E. 2007. Docosahexaenoic acid supplementation decreases remnant-like particle-cholesterol and improves omega-3 index in hypertriglyceridemic men1-3.. Journal of Nutrition. 2007. Journal Nutrition 138:30-35, 2008.
Interpretive Summary: Cardiovascular disease is the number one killer in United States. Elevated plasma concentration of remnant-like particle-cholesterol (RLP-C) or remnant lipoprotein cholesterol, reduced concentration of omega-3 fatty acids in plasma (ratio between eicosapentaenoic acid and arachidonic acid or EPA:AA) and red blood cell (RBC) omega-3 index (sum of EPA plus DHA as a percentage of total fatty acids) are novel markers used to assess risk for cardiovascular disease (CVD). The effects of DHA supplementation on plasma concentrations of RLP-C, EPA:AA, and RBC omega-3 index in hypertriglyceridemic men who are at increased risk for CVD has not been studied. Men with elevated triglycerides (17/group) supplemented their diets with either DHA oil (DHA 3 g/d) or olive oil for 90 days; 12-h fasting blood samples were drawn at the start, middle and end of the intervention. DHA supplementation reduced the plasma RLP-C by 21%; it also caused a more than 2 fold increase in the ratio between plasma EPA and AA, and the omega-3 index. RLP-C concentration was positively associated with plasma concentration of triglycerides and negatively associated with those of EPA and DHA. These results along with those previously published from this study (decreased triglycerides, and number of total and small dense LDL particles, increased HDL) suggest several possible means by which DHA may improve cardiovascular health.
Technical Abstract: Background: Plasma remnant-like particle-cholesterol (RLP-C) and RBC omega-3 index are novel risk factors for cardiovascular disease. Effects of docosahexaenoic acid (DHA) supplementation on these risk factors in hypertriglyceridemic men have not been studied. Objective: We determined effects of DHA supplementation on concentrations of plasma RLP-C, and on RBC omega-3 index; we also determined associations between concentrations of plasma RLP-C, with those of plasma lipids and fatty acids. Design: Hypertriglyceridemic men aged 39-66 y, participated in a double-blind, randomized, placebo controlled, parallel study. They received no supplements for the first 8 days and received either 7.5 g/d DHA oil (3 g DHA/d) or olive oil (placebo) for the last 90 d. Fasting blood samples were collected on study d -7, 0 (baseline), 45 (mid-intervention), 84 and 91 (end-intervention). Results: DHA supplementation for 45 d decreased (p<0.05) fasting RLP-C (by 36%) and increased plasma EPA:AA (100%) and the RBC omega-3 index (109%). Continued supplementation with DHA between d 45 and 91further increased the RBC omega-3 index (162%) and the plasma EPA:AA (137%) compared to baseline values. RLP-C concentration was positively associated (p<0.005) with plasma concentrations of triacylglycerols, triacylglycerols:HDL-C, total-C:HDL-C, Apo B, C III, and E, and 18:1 n-9; it was negatively associated (p<0.05) with plasma concentrations of DHA, EPA, HDL-C, LDL-C:Apo B, and HDL-C:Apo A. Supplementation with the placebo oil did not alter any of the response variables tested. Conclusions: In addition to other mechanisms, DHA supplementation may improve cardio-vascular health by lowering RLP-C, and increasing EPA:AA and RBC omega-3 index.