Testosterone, aging, and body composition in men from Harare, Zimbabwe

To examine age-related changes in body composition and testosterone (T) among men in an urban sub-Saharan African population, measures of body composition and salivary T were obtained from 109 males ages 20-78 in Harare, Zimbabwe. Measures included height, weight, suprailiac and triceps skinfold, and percent body fat by bioelectric impedance (BIA). Saliva samples were assayed for T using radioimmunoassay. Average BMI of the overall sample (23.16 (SD = 18.12) kg/m(2) was close to Western populations, while salivary T levels (AM = 196 ± 96 pmol/l; pm = 172 ± 98 pmol/l) were much lower. Both morning (beta = -0.535; P < 0.001) and afternoon salivary T declined with age (beta = -0.385; P < 0.001). Multiple regression models indicate that pm salivary T (beta = 0.24; P = 0.025), was a predictor of fat-free mass, but neither am nor pm salivary T was related to fat mass or other measures of body composition. In addition, height was significantly related to pm salivary T levels in men under the age of 60. Multivariate regression indicates that pm salivary T is a predictor of fat-free mass when controlled for height and adiposity. These findings suggest that T is related to both lean mass and overall body size among men from a non-Western nonsubsistence population. As such they are consistent with the hypothesis that bioavailable T plays a role in energetic allocation among human males.