Body size accounts for most differences in bone density between Asian and Caucasian women

We compared bone mineral density (BMD) of the whole body (and subregions: arm, leg, and pelvis), hip, spine, lateral spine, wrist, and forearm among Caucasian and Asian women at four geographic centers (Honolulu, HI: Nottingham, UK; Portland, OR: Copenhagen, Denmark). Data were derived from the baseline examination of 1367 Caucasian and 162 Asian women enrolled in the 1609-subject Early Postmenopausal Interventional Cohort (EPIC) study. After adjusting for age, study site, years postmenopause, and years of estrogen use, BMD was approximately 4-6% lower (P < 0.05) among Asian women at most skeletal sites, but there was no significant difference for wrist or forearm BMD. Adding height, lean body mass, fat mass, and/or quadriceps muscle strength to the regression models reduced the racial differences at most skeletal sites; after these additional adjustments, Asian women had significantly lower BMD only for the lateral spine (-4.4%: P < 0.005), arm (- 2.20%: P < 0.05) and leg (-1.65%: P < 0.05), whereas the wrist was significantly greater (4.64%; P < 0.005) for Asian women. Further research is needed to determine why racial differences in BMD persist at certain skeletal sites, but not others, after adjusting for body size.