Dietary calcium intake relates to bone mineral density in premenopausal women

Bone density and Ca intake were assessed in fifty-six healthy premenopausal women, aged 21-47 years. Bone density was measured at the spine (lumbar vertebrae 1-4, anterio-posterior view), the non-dominant femur (neck, Ward's triangle and trochanter) and radius (33% distal and ultradistal) using dual energy X-ray absorptiometry (Lunar DPX-L). The mean values (SD) for bone density (g/cm2) were 1.18 (0.10) at the lumbar spine, 0.81(0.10) at the trochanter and for Ca intake 783 (329) mg. Bone density values were close to published normal values for young women and the Ca intakes were close to the recommended levels for the UK. However, there was a wide range especially in dietary Ca intake, and 27% of the group were at or below 500 mg/d. Correlations between Ca intake and bone density were highly significant at all three femoral sites (neck r 0.41; Ward's triangle r 0.40, P < 0.01; trochanter r 0.47, P < 0.001), significant at the spine (r 0.27, P < 0.05) but not found at the radius. These correlations were independent of body mass. The low levels of Ca intake found in a substantial proportion of this selected group of young women and their association with low femoral bone density are cause for concern.