The small, dense LDL phenotype as a correlate of postprandial lipemia in men

The atherogenic dyslipidemia of the insulin resistance syndrome is characte rized by hypertriglyceridemia (hyperTG), elevated apolipoprotein (apo) B le vels, reduced high-density lipoprotein (HDL) cholesterol concentrations and by an increased proportion of small, dense low-density lipoprotein (LDL) p articles. Although the hyperTG-low HDL cholesterol dyslipidemia has been as sociated with an impaired clearance of dietary fat, the contribution of the small, dense LDL phenotype as an independent predictor of postprandial tri glyceride (TG) clearance remains uncertain. We have therefore compared the postprandial TG response among three subgroups of men characterized by smal l, intermediate or large LDL particles in a total sample of 69 men (mean ag e +/- SD; 45.1 +/- 10.5 years). To identify men with small versus large LDL particles, the first (LDL peak particle diameter < 251.9 <Angstrom>) and t he third (> 257.6 Angstrom) tertiles of the distribution of LDL particle di ameters were used as cutoff points. Men with small, dense LDL particles had the expected fasting dyslipidemic profile thigh TG-low HDL cholesterol lev els) compared to men with large, buoyant LDL particles. The oral lipid tole rance test revealed that men with small, dense LDL particles had significan tly higher total-,large-, and medium-TG-rich lipoprotein (TRL) responses to a fatty meal than men with large LDL particles (P < 0.03). In addition, wi thin a subgroup of normolipidemic men (TG < 2.3 mmol/l and HDL cholesterol > 0.9 mmol/l), those with small, dense LDL particles had higher levels of t otal-, medium- and small-TRL responses compared to men with large, buoyant LDL particles (P < 0.05). Moreover, normotriglyceridemic men with small, de nse LDL had higher levels of small-TRLs measured 8 h after the ingestion of the fat meal (P < 0.05) compared to normolipidemic men with large, buoyant LDL particles. Results of the present study suggest that the dense LDL phe notype may be an additional fasting marker of an exaggerated postprandial T G response and of an impaired clearance of TRLs. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.