Impact of increasing calcium intake with dairy vs. calcium carbonate on calcium retention in overweight adolescents

Abstract

This study assessed the effect of calcium supplementation from dairy vs. calcium carbonate sources on calcium (Ca) retention in overweight and obese adolescent boys and girls. Twenty-three girls (BMI 33 ± 5 kg/m2) and seventeen boys (BMI 28 ± 5 kg/m2), aged 12–15 years, participated in two 3-week controlled feeding trials, separated by a 3-week washout period. Each subject consumed a controlled basal diet during both trials that provided their individualized energy need and 778 ± 147 mg Ca/day. Using a two period crossover design, subjects received no additional Ca in a soy-based product (Control) during one 3-week testing period and were randomized to receive an additional 675 mg Ca/day as dairy Ca (Dairy) or Ca carbonate (CC) in the other testing period. Ca intake and source of Ca were manipulated through a frozen product consumed twice each day. All urine and feces were collected during each 3-week period. Diet, fecal, and urine samples were each pooled for 24-hour periods and measured for Ca content by Inductively Coupled Plasma Spectrophotometry. Subjects retained (intake-feces-urine) more (p<0.0001) Ca when they consumed the higher Ca product (552 ± 213 mg Ca/day for the CC group and 578 ± 221 mg Ca/day for the Dairy group) compared to the lower Ca period (296 ± 169 mg Ca/day for Control). Thus, doubling Ca intake through either dairy or Ca carbonate supplementation led to a nearly two-fold increase in Ca retention. The proportion of intake retained (~38%) during pubertal growth in obese adolescents was not dependent on Ca intake, as observed in adults. Supported by NIH DK066108, National Dairy Council and test products were a gift from The Schwan Food Company.