Effects of omega-3 fatty acids on postprandial triglycerides and monocyte activation

Epidemiologic studies suggest that elevated postprandial triglycerides (ppTG) are associated with future cardiovascular events. Monocyte activation plays an important role in vascular diseases. Omega-3 fatty acids (n3-FA) lower fasting TG levels. The effects of n3-FA on ppTG and the role of ppTG for monocyte activation are insufficiently understood.

23 healthy volunteers and 30 non-diabetic patients with documented coronary artery disease were subjected to an oral TG tolerance test (OTTT) consisting of 80 g cream fat or to water as control (H(2)O). Patients were treated with 4 g n3-FA/day or placebo for 3 weeks in a randomized, placebo-controlled, double-blind, crossover study. Relative postprandial TG increase reached its maximum 4 h after fat intake (185.1 ± 10.9% of baseline). n3-FA reduced fasting TG from 137.1 ± 12.9 to 112.2 ± 8.6 mg/dl (p < 0.05), and maximum ppTG concentrations from 243.6 ± 24.6 to 205.8 ± 17.1 mg/dl (p < 0.05), while relative TG increase (192.8 ± 12.7%) was comparable to placebo. Relative monocytopenia and neutrophilia were detected following fat intake, which was unaffected by n3-FA and also detectable in the H(2)O group. Serum chemotactic cytokine (MCP1 and fractalkine) concentrations and monocyte migration were not affected by fat intake or n3-FA. Monocyte activation markers CD11b and CD14, monocyte subpopulations CD16(+)CD14(high) and CD16(+)CD14(low), sICAM serum levels and markers of oxidative stress remained unchanged by fat intake or n3-FA.

The postprandial TG increase does not stimulate monocytes beyond their circadian activation patterns. n3-FA reduce fasting TG and the postprandial TG increase. n3-FA may therefore allow to prospectively study whether selected patients benefit from TG-lowering independent of LDL- and HDL-cholesterol.