Epidemiological studies have shown correlation between low incidence of coronary heart disease and high consumption of fish products. It has been suggested that this may be due to the high content of polyunsaturated fatty acids of the n-3 fatty acid group in fish oil. In animal studies eicosapentaenoic acid (EPA) inhibited attachment of monocytes to the arterial endothelium.

Adhesion assay was performed on the endothelial cells of the human umbilical vein with 25, 50, 100, 200 micrometer EPA-treated U937 cells. The endothelial cells were activated with lipopoysaccharide (LPS). The adhesion assay was repeated with oxidized EPA. EPA was oxidized with CuSO4 and ascorbic acid.

Viability of U937 cells were not affected by concentrations up to 200 micrometer of EPA and oxidized EPA. LPS treatment of endothelium notably increased the number of U937 cells attached to endothelial cells on the adhesion assay. However, treatment of EPA, native or oxidized, to U937 cells did not affect the number of U937 cells attached to LPS activated endothelial cells.

EPA treatment, native or oxidized, of U937 cells did not affect U937 cell-endothelial cell adhesion. This suggests that inhibition of monocyte-endothelial cells attachment by EPA is not due to the effects of EPA on monocytes.