Lifestyle determinants of bone mineral: A comparison between prepubertal Asian- and Caucasian-Canadian boys and girls

The purpose of this study was to examine the difference in lifestyle and mo rphometric factors that affect bone mineral and the attainment of peak bone mass in 168 healthy Asian(n = 58) and Caucasian (n = 110) Canadian, prepub ertal girls and boys (mean age 5.9 +/- 0.7) living in close geographical pr oximity. DXA (Hologic 4500) scans of the proximal femur (with regions), lum bar spine, and total body (TB) were acquired. We report areal bone mineral densities (aBMD g/cm(2)) at all sites and estimated volumetric density (vBM D, g/cm(3)) at the femoral neck. Dietary calcium, physical activity, and ma turity were estimated by questionnaire. Of these prepubertal children, all of the boys and 89% of the girls were Tanner stage 1. A 2 x 2 ANOVA demonst rated no difference between ethnicities for height, weight, body fat, or bo ne mineral free lean mass. Asian children consumed significantly less dieta ry calcium (35%) on average and were significantly less active (15%) than t heir Caucasian counterparts (P < 0.001). There were significant ethnicity m ain effects for femoral neck bone mineral content (BMC) and alpha BMD (both P < 0.001) and significant sex by ethnicity interactions (P < 0.01). The A sian boys had significantly lower femoral neck BMC (11%), aBMD (8%), and vB MD (4.4%). At the femoral neck, BMFL mass, sex, and physical activity expla ined 37% of the total variance in aBMD (P < 0.05). In summary, this study d emonstrated differences in modifiable lifestyle factors and femoral neck bo ne mineral between Asian and Caucasian boys.