High habitual calcium intake attenuates bone loss in early postmenopausal Chinese women: an 18-month follow-up study.

This study assessed the association of habitual dietary calcium intake and bone loss in early postmenopausal women. Four hundred fifty-four healthy postmenopausal Chinese women were enrolled for this 18-month cohort study. The subjects were 48-62 yr of age and within 12 yr of natural menopause. Dietary intake was assessed by the food frequency method, and bone mass was measured using dual energy x-ray absorptiometry at baseline and 9 and 18 months. The association between mean habitual dietary intake over the follow-up period and the rate of bone loss was examined. During the 18-month follow-up, the total loss rates of BMD at the whole body, lumber spine, femoral neck, and total hip were 1.28, 0.60, 1.54, and 0.56% (all P < 0.01). Subjects were stratified into four quartiles according to calcium intake during the period of follow-up. Quartiles I-IV had median intakes of 341, 505, 682, and 934 mg Ca/d. Subjects in quartile IV had significantly less BMD loss at the whole body and less BMD/bone mineral content loss at Ward's triangle, even after adjustments for confounding factors (by analysis of covariance). Multiple linear regression analyses showed significant positive associations between calcium intake and BMD change at the whole body (P = 0.006) and Ward's triangle (P = 0.021). Calcium intake was significantly associated with bone mineral content change at the trochanter (P = 0.025) and Ward's triangle (P < 0.001). No significant effect of calcium intake at the spine was found. In conclusion, habitual dietary calcium intake had a beneficial effect on bone loss at the whole body and some regions of the hip. Our findings suggest that an intake exceeding 900 mg calcium/d was helpful in the prevention of cortical bone loss among early postmenopausal Chinese women.