Plasma estradiol, testosterone, and sex hormone-binding globulin (SHBG) were studied in relation to plasma lipoproteins, high density lipoprotein (HDL) subfractions, and apolipoproteins in 73 healthy but sedentary middle-aged men. Among potentially confounding variables, a strong positive association was found between estradiol levels and cigarette use, while testosterone and SHBG correlated negatively with percent body fat and alcohol intake. After adjustment for smoking, percent body fat, and alcohol, plasma estradiol levels correlated negatively with total cholesterol and low density lipoprotein cholesterol, and testosterone levels correlated positively with apolipoprotein B, while SHBG levels correlated positively with HDL2 mass and apolipoprotein A-I. SHBG was also strongly associated with the waist to hip girth ratio (WHR). Adjustment for WHR eliminated the significant associations of SHBG with triglycerides, HDL2 mass, and apolipoprotein A-I. SHBG levels and WHR may reflect tissue sensitivity and the impact of exposure to fluctuating levels of sex hormones for a period of days, or longer. These variables may provide more insight into the role of sex hormones in lipoprotein metabolism than do single samples of circulating hormones. It is also suggested that long term effects of sex hormones on adipose tissue distribution may at least partially underlie sex-related differences in lipoprotein metabolism.
Anatomical adipose tissue distribution patterns are reported to relate to plasma lipids and risk of cardiovascular disease. Waist to hip girth ratios (WHR) and subscapular 10 triceps skinfold thickness ratios (STR) were compared with percent body fat and body mass index values as correlates of plasma lipids and lipoprotein cholesterol and serum lipoprotein subfraction mass by analytic ultracentrifugation in 81 sedentary middle-aged men in a typical range of adiposity. WHR was significantly and positively correlated with plasma concentrations of triglycerides, cholesterol, and low and very low density lipoprotein (LDL and VLDL) cholesterol and inversely correlated with high density lipoprotein (HDL) cholesterol. STR followed these trends, though less strongly, in relation to plasma triglycerides, VLDL cholesterol, and HDL cholesterol. Pronounced differences were found between regional adiposity patterns in their relationships to lipoprotein subtractions, as determined by analytic ultracentrifugation. WHR was negatively correlated with HDL2 (flotation rate F1.2 3.5–9), positively with small LDL (Sj0–7), intermediate density lipoprotein (Sj12–20), and VLDL (Sj20–400), while STR correlated with larger LDL (Sj7–12) and larger VLDL (Sj60–400). Overall adiposity was not significantly associated with plasma lipoprotein levels after adjusting for regional adiposity patterns. Plasma sex hormonebinding globulin and percent free testosterone were associated with regional adiposity, but did not account for the correlations between WHR and lipoproteins. WHR and STR are measures of fat distribution that correlate with plasma lipoprotein profiles consistent with cardiovascular disease risk and have different relationships to lipoprotein mass subfractions.
The National Cholesterol Education Program (NCEP) recommends a low-saturated-fat, low-cholesterol diet, with weight loss if indicated, to correct elevated plasma cholesterol levels. Weight loss accomplished by simple caloric restriction or increased exercise typically increases the level of high-density lipoprotein (HDL) cholesterol. Little is known about the effects on plasma lipoproteins of a hypocaloric NCEP diet with or without exercise in overweight people.
In 875 predominantly white (89%), postmenopausal women, aged 45–-65 years, enrolled in the Postmenopausal Estrogen/Progestin Interventions Trial, univariate analysis showed that mean total cholesterol, low-density lipoprotein cholesterol (LDL-C), apolipoprotein B, and triglyceride (TG) levels were positively associated with age (p < 0.01) across 5-year age groups, whereas high-density lipoprotein cholesterol (HDL-C) and apolipoprotein A-I did not vary by age. HDL-C levels were positively associated with leisure time exercise level (p < 0.01), income (p < 0.01), alcohol intake (p < 0.01), and education level (p < 0.05). Current smokers have lower HDL-C levels than former smokers and those who never smoked (p < 0.01). TG levels were negatively associated with leisure time exercise (p < 0.01) and education (p < 0.01), and higher TG levels occurred in current smokers compared with former smokers and those who never smoked (p < 0.05). LDL-C showed no significant associations with these lifestyle variables. Increased adiposity, as determined by body mass index (BMI) or in body fat distribution as defined by waist/hip ratio (WHR), was significantly negatively associated with HDL-C levels and positively associated with total cholesterol, LDL-C, and TG. Multivariate models showed that 27% of the variance of log triglyceride was explained by WHR, BMI, and smoking, and 31% of the variance of HDL-C was explained by these factors plus alcohol and leisure time exercise.
In summary, we conclude that the analysis of the blood profiles of elite runners offers no explanation for their superior fitness of physical ability when compared to the good runners. Selected enzymes related to cellular or tissue damage may be elevated in distance runners and could be classified as abnormal on routine clinical evaluation if unaware of their physical lifestyles. It is also important to note that certain blood profile parameters, especially the hematocrit, could be classified as abnormally low. Finally, the high degree of daily physical activity performed by the elite runners and good runners appears to be associated with a lipoprotein profile consistent with a low risk for development of coronary artery disease manifestations. These profiles persist despite increasing age in active running males.
