WHOLE-BODY BONE, FAT, AND LEAN MASS IN BLACK-AND-WHITE MEN

This research describes the effects of age, ethnicity, and body size a nd composition on whole body bone mass and bone density in healthy bla ck and,white men, We measured 79 male subjects, 42 white and 37 black, ranging in age from 33 to 64 years, Whole body bone mineral content ( WBBMC) and bone mineral density (WBBMD), as well as fat and lean mass, were evaluated with a Hologic 1000W bone densitometer. We explore the utility of different methods of controlling for variations in body si ze in the two ethnic groups, There are statistically significant ethni c differences only in the bone mass variables, The black men had a 15% higher WBBMC (3111 vs, 2712 g, p < 0.0001) and a 8% higher WBBMD (1.2 5 vs, 1.16 g/cm(2), p = 0.001) than the white men, Dividing WBBMD by h eight reduced the black/white difference to 6%. WBBMC, WBBMC/height, a nd WBBMD are strongly and significantly correlated with weight, body m ass index (BMI), and body composition; correlations tended to be lower for WBBMD/height, Age is not significantly correlated with any of the variables in either ethnic group (p greater than or equal to 0.10), I n multivariate linear regression models for predicting WBBMC or WBBMD, the two best models contained height, weight, and an interaction of e thnicity and,weight (model r(2) = 0.72 for WBBMC and r(2) = 0.47 for W BBMD); and height, lean mass, and an ethnicity-fat interaction (model r(2) = 0.69 for WBBMC and r(2) = 0.46 for WBBMD), Using analysis of co variance, we found that controlling for lean mass and height reduced t he black/white difference in bone mass from 14.7 to 9.8%.