CALCIUM-METABOLISM IN GIRLS - CURRENT DIETARY INTAKES LEAD TO LOW RATES OF CALCIUM-ABSORPTION AND RETENTION DURING PUBERTY

We evaluated the effects of self-selected diets on calcium absorption and calculated retention in girls during pre-, early, and late puberty . Dietary calcium absorption was measured in 51 girls aged 4.9-16.7 y by using a dual-tracer stable-isotope technique. We found that calcium intake was similar among girls of all ages and all degrees of puberta l development and was below the recommended dietary allowance (1200 mg /d) for 21 of 25 girls aged greater than or equal to 11 y. The early p ubertal period was associated with a higher percent of dietary calcium absorption (34.4 +/- 11.9%) than was the prepubertal (27.7 +/- 8.2%) or late pubertal periods (25.9 +/- 7.8%). Calculated calcium retention averaged 132 +/- 83 mg/d in prepubertal girls, 161 +/- 88 mg/d in ear ly pubertal girls, and 44 +/- 91 mg/d in late pubertal girls. Peak cal cium retention during early puberty was far below that previously repo rted after higher calcium intakes. We conclude that peak periods for c alcium retention for girls are in the pre- and early pubertal periods. The current calcium intake of American girls during the pubertal grow th period may not enable maximal mineral retention; therefore, increas ed calcium intakes should be considered.