Influence of mild to moderately elevated triglycerides on low density lipoprotein subfraction concentration and composition in healthy men with low high density lipoprotein cholesterol levels

Epidemiologic studies have shown that a dyslipoproteinemia with low concent rations of high density lipoprotein (HDL) cholesterol and elevated serum tr iglycerides (TG) is associated with a particularly high incidence of corona ry artery disease. This lipid profile is associated with increased concentr ations of small, dense low density lipoprotein (LDL) particles. To evaluate the role of mild to moderately elevated TG on the LDL subfraction profile in patients with low HDL cholesterol, concentration and composition of six LDL subfractions was determined by density gradient ultracentrifugation in 41 healthy men (31 +/- 9 years, body mass index (BMI) 25.1 +/- 3.9 kg/m(2)) with equally low HDL cholesterol levels < 0.91 mmol/l but different TG lev els: TG < 1.13 mmol/l, n = 16; TG = 1.13-2.26 mmol/l, n = 13; TG = 2.26-3.3 9 mmol/l, n = 12. Those men with moderately elevated TG levels between 2.26 and 3.39 mmol/l had significantly higher concentrations of very low densit y lipoprotein (VLDL), intermediate low density lipoprotein (IDL), and small , dense LDL apoB and cholesterol than men with TG < 1.13 mmol/l. With incre asing serum TG, the TG content per particle also increased in VLDL, IDL as well as total LDL. particles while the cholesterol and phospholipid (PL) co ntent decreased in VLDL and IDL, but not in LDL particles. LDL subfraction analysis revealed that only large, more buoyant LDL particles (d < 1.044 g/ ml) but not the smaller, more dense LDL, were enriched in TG. Small, dense LDL particles were depleted of free cholesterol (FC) and FL. This study has shown that in men with low HDL cholesterol levels mild to moderately eleva ted serum TG strongly suggest the presence of other metabolic cardiovascula r risk factors and in particular of a more atherogenic LDL subfraction prof ile of increased concentration of small, dense LDL particles that are deple ted in surface lipids. (C) 1999 Elsevier Science Ireland Ltd. All rights re served.