Associations of age, adiposity, menopause, and alcohol intake with low-density lipoprotein subclasses

We used nondenaturing polyacrylamide gradient gel electrophoresis to examine the associations of age, adiposity, menopause, and alcohol intake with LDL subclasses in 355 individuals. The absorbency of protein stain was used as an index of mass concentrations at intervals of 0.05 nm within seven LDL subclasses: LDL-IVB (22.0 to 23.2 nm), LDL-IVA (23.3 to 24.1 nm), LDL-IIIB (24.2 to 24.6 nm), LDL-IIIA (24.7 to 25.5 nm), LDL-II (25.5 to 26.4 nm), LDL-I (26.0 to 28.5 nm), and intermediate-size lipoproteins (ISL, 28.0 to 32.0 nm). Age and alcohol intake were obtained from questionnaires, and body mass index was computed from clinic measurements of weight and height. In adult men, body mass index correlated positively with LDL-III, and alcohol intake correlated positively with larger LDL-I. Age was positively correlated with LDL-IIIA and ISL in both men and women and with LDL-IIIB and LDL-II in women. Postmenopausal women had higher LDL-IIIA, LDL-II, and ISL than both premenopausal and premenarchal females. Adult males, > or = 18 years old, had higher levels of LDL-IIIA and LDL-II than younger males. Adjustment for fasting plasma triglyceride levels eliminated the significant associations between age and LDL-IIIA in both men and women and between age and LDL-II in women. Partial correlation analyses showed that reductions in the LDL peak diameter associated with increasing age, male sexual maturation, menopause, and adiposity are attributable to increases in the LDL-IIIA subclass. Thus, densitometric measurements of protein-stained gradient gels reveal specific relationships between LDL subclasses and age, adiposity, and alcohol intake beyond those identified by the LDL peak or average diameter.