Sialic acid content of low density lipoprotein and its relation to lipid concentrations and metabolism of low density lipoprotein and cholesterol

A low sialic acid content in low density lipoprotein (LDL) has been associa ted with atherogenicity and coronary artery disease (CAD) in many but not a ll studies. We investigated associations of the sialic acid-to-apolipoprote in B (apoB) ratio of LDL with lipoprotein lipid concentrations, kinetics of LDL, metabolism of cholesterol, and the presence of CAD in 98 subjects (CA D(+), n = 56; CAD(-),n = 42). The sialic acid ratios of total, dense, and v ery dense LDL were lower in the CAD+ than CAD- subjects, especially at high sialic acid ratios. The LDL sialic acid ratio was inversely associated wit h respective lipid and apoB concentrations and positively with lipid-to-apo B ratios of LDL. The transport rates (TRs) for total and dense LDL apoB wer e negatively associated with their sialic acid ratios. The sialic acid rati o of dense LDL, but not that of total LDL, was inversely correlated with se rum levels of cholesterol precursor sterols, indicators of cholesterol synt hesis, and positively with serum levels of plant sterols, indicators of cho lesterol absorption. In addition, the TR for dense LDL was positively corre lated with cholesterol synthesis. In conclusion, a low LDL sialic acid rati o was associated with CAD, high numbers of small LDL particles, and a high TR for LDL apoB, and in dense LDL also with high synthesis and low absorpti on of cholesterol.