ZINC BALANCE IN ADOLESCENT FEMALES CONSUMING A LOW-CALCIUM OR HIGH-CALCIUM DIET

There is increasing evidence that calcium intake up to the threshold a mount (1480 mg/d) increases bone mass during growth. However, there is concern that such a high calcium intake may interfere with the utiliz ation of other nutrients such as zinc, which is also important for ske letal development. The purpose of our study was to investigate the eff ect of long-term calcium supplementation on zinc utilization in 26 ado lescent females ((x) over bar +/- SD age 11.3 +/- 0.5 y) during a 14-d period. Each day subjects consumed a metabolic diet containing 722 mg Ca and 6.3 mg Zn. Participants were randomly assigned to receive eith er a placebo or a calcium supplement containing 1000 mg supplemental C a/d as calcium citrate malate. Supplementation began 15 wk before the balance period to allow for adaptation to the greater calcium intake. Mean (+/- SD) zinc balance (0.8 +/- 0.8 compared with 0.3 +/- 1.1 mg/d , P = 0.23), fecal zinc (4.3 +/- 0.6 compared with 4.7 +/- 1.4 mg/d, P = 0.27), urinary zinc (0.4 +/- 0.2 compared with 0.5 +/- 0.1 mg/d, P = 0.55), and net zinc absorption (21% compared with 15%, P = 0.33) wer e not significantly different between the high- and low-calcium groups . Our results suggest that increasing the recommended dietary allowanc e of calcium to 1500 mg/d as recommended by the National Institutes of Health consensus panel will not have adverse effects on zinc utilizat ion in adolescent females.