Low density lipoprotein particle diameter in young, nonobese, normolipidemic Japanese men Original Research Article

Background: prospective studies have demonstrated that a predominance of small, dense LDL particles (pattern B) precedes the clinical onset of coronary heart disease. Prevalence and characteristics of subjects with this LDL size abnormality were studied in young, nonobese, Japanese normolipidemic men. Methods and results: LDL peak particle diameter (PPD) was measured by continuous disc polyacrylamide gel electrophoresis in 223 nonobese normolipidemic men aged 18–20 years (mean±S.D. body mass index: 21.9±3.7 kg/m2, total cholesterol: 180±29 mg/dl, triglyceride: 62±34 mg/dl, HDL cholesterol: 58±12 mg/dl). Men with small LDL (PPD <25.8 nm) were found in only 5.4% (n=12) whereas 197 men (88.3%) had a preponderance of large LDL (PPD 26.3 nm). As compared with men in a top tertile (PPD 27.5 nm) those in a low tertile (PPD <26.9 nm) had higher serum levels of LDL cholesterol (120±31 vs 104±24 mg/dl), triglyceride (72±39 vs 49±16 mg/dl) and apolipoprotein (apo) B (84±21 vs 68±14 mg/dl), and lower HDL cholesterol (54±10 vs 60±12 mg/dl). They also had greater body mass index (23.2±4.6 vs 20.9 3.1 kg/m2) and percent body fat (21.5±7.7 vs 17.5±4.9%). LDL-PPD was positively correlated with HDL cholesterol (R=0.20, P=0.002) and was negatively correlated with apoB (R=0.34, P<0.001), triglyceride (R=0.32, P<0.001), percent body fat (R=0.26, P<0.001), body mass index (R=0.24, P<0.001), fat mass (R=0.23, P=0.001), total cholesterol (R=0.20, P=0.002). In multiple regression analysis, apoB, triglyceride, HDL cholesterol, apoAI and percent body fat explained 18% of LDLPPD variability. Conclusion: even in young, nonobese, normolipidemic men, LDL size appears to be associated with triglyceride-rich lipoprotein metabolism and body fat.