Is the gender difference in LDL size explained by the metabolic complications of visceral obesity?

Several studies have reported a significant gender difference in low-density lipoprotein (LDL) size, with men being characterized by smaller, denser LDL particles than women, and it has been suggested that the contribution of the greater accumulation of visceral adipose tissue in men compared with women may be a factor potentially contributing to the gender difference in LDL heterogeneity.

We measured LDL particle size by 2-16% nondenaturing polyacrylamide gradient gel electrophoresis in 299 men and 231 women in whom visceral adipose tissue accumulation was measured by computed tomography. A fasting plasma lipoprotein-lipid profile was also obtained in all subjects.

Overall, the men were characterized by a more deteriorated metabolic risk factor profile, which included higher plasma insulin and triglyceride levels, a greater visceral adipose tissue accumulation (P < 0.001) and smaller LDL particles (251.7 +/- 5.2 vs. 254.4 +/- 4.2 A, P < 0.0001). This gender difference in LDL peak particle diameter remained significant (252.4 +/- 4.3 vs. 253.5 +/- 4.3 A, P < 0.01) after adjustment for sex-specific differences in plasma triglyceride levels by covariance analysis. Significant negative correlations were noted between the LDL particle diameter and the triglyceride concentrations in both genders (r = -0.52 and r = -0.36, P < 0.0001 for the men and women, respectively), with no gender difference in this relationship being found. However, viscerally obese women (visceral adipose tissue levels > 100 cm2) with increased plasma triglyceride concentrations (> 2.0 mmol L-1) still had larger LDL particles than viscerally obese men with a similar elevation in their triglyceride levels (251.6 +/- 4.9 vs. 248.7 +/- 4.5 A, P < 0.01).

Results of the present study suggest that the reduced LDL particle size observed in men compared with women cannot be entirely explained by their higher visceral adipose tissue accumulation and increased plasma triglyceride levels. Moreover, the gender difference in LDL size could be influenced, at least in part, by the severity of the hypertriglyceridaemic state.