Dietary calcium, sex hormones, and bone mineral density in men.

OBJECTIVE To evaluate the factors that determine bone mineral density at axial and appendicular sites in normal men. DESIGN Measurement of bone mineral density of the radius by single photon absorptiometry and of the lumbar spine and hip by dual photon absorptiometry to assess their relation with various determinants of bone mineral density. Dietary calcium was assessed from a questionnaire validated against a four day dietary record. SETTING Local community, Sydney, Australia. PATIENTS 48 Men (aged 21-79, median 44) recruited from the local community including 35 male cotwins of twin pairs of differing sex recruited from the Australian National Health and Medical Research Council twin registry for epidemiological studies on determinants of bone mineral density. MAIN OUTCOME MEASURES Bone mineral density of the axial and appendicular skeleton and its relation to age, anthropometric features, dietary calcium intake, and serum sex hormone concentrations. RESULTS Dietary calcium intake (g/day) was a significant predictor of bone mineral density of axial bones, explaining 24% and 42% of the variance at the lumbar spine and femoral neck respectively. This effect was independent of weight. In contrast with the axial skeleton, bone mineral density at each forearm site was predicted by weight and an index of free testosterone but not by dietary calcium intake. CONCLUSIONS Dietary calcium intake has a role in the determination or maintenance, or both, of the axial but not the appendicular skeleton in adult men.