Omega-3 fatty acids and lipoprotein associated phospholipase A2 in healthy older adult males and females

Lipoprotein associated phospholipase A2 (Lp-PLA2) is a novel inflammatory factor that has been independently associated with stroke and cardiovascular disease (CVD). Omega-3 fats have been implicated in reducing inflammation associated with CVD. The aim of this study was to determine if an 8-week isocaloric diet supplemented with eicosapentaenoic acid (EPA) and docosahexaenoic (DHA) in the form of fish oil or alpha-linolenic acid (ALA) in the form of flaxseed oil would alter Lp-PLA2 among healthy adults ages 50 years and older. Fifty-nine healthy adults (75% female, average age 61 years) were randomized to one of three groups with equal amounts of total fat intake. All capsules contained 1 g of fat. The control group (n = 19) consumed olive oil capsules (11 g/day); the ALA group (n = 20) consumed flaxseed oil capsules (11 g/day) and the EPA/DHA group (n = 20) consumed fish oil capsules (2 g/day + 9 g/day of olive oil). Fasting blood samples were obtained before and after the 8-week intervention for determination of Lp-PLA2 mass and activity as well as lipid values. We did not find any significant changes in Lp-PLA2 mass or activity after the intervention in any of the groups; however, change in oxidized LDL was associated with change in Lp-PLA2 mass (r = 0.37, p<0.01). Supplementing the diet with omega-3 fatty acids for 8-weeks did not influence Lp-PLA2 activity or mass among older adults; altering oxidized LDL may be necessary to see changes in Lp-PLA2 levels. (Authors abstract)
The novel inflammatory factor Lp-PLA is a macrophage derived enzyme that when released binds to apo B on low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C). These compounds contribute significantly to the inflammation associated with atherosclerosis. Lp-PLA mass and activity have been shown to be independent predictors of coronary heart disease and ischemic stroke and higher levels of circulating Lp-PLA2 appear associated with coronary calcification, endothelial and plaque instability. Omega six polyunsaturated fatty acids (PUFA)s have proinflammatory capacities; while the omega -3 PUFAs have anti-inflammatory effects.  Because Lp-PLA2 originates from macrophages and omega-3 fats have shown to decrease inflammatory cytokine synthesis from these cells, the authors hypothesize there may be a direct effect of omega-3s on Lp-PLA levels. Therefore, the purpose of this study was to determine if 8 weeks of dietary supplementation with EPA and DHA in the form of fish oil or ALA in the form of flaxseed oil alters Lp-PLA among healthy adults ages 50 years and older. No changes in Lp-PLA2 activity or mass after supplementing healthy older adults with omega- 3 fatty acids, 5.3% of calories (11 g/day) from ALA or (2 g/day) EPA/DHA. Oxidized LDL levels did not change and the other lipids decreased but not significantly. Because adipose tissue represents dietary intake over 6 to 12 months perhaps a longer intervention with omega-3 fats could influence Lp-PLA2 levels. The significant correlation between Lp-PLA2 activity and oxidized LDL may suggest that oxidized LDL needs to be altered before changes in Lp-PLA2 can be seen. (Editors comments)