Increased efficiency of calcium absorption during short periods of inadequate calcium intake in girls

• Published in: The American journal of clinical nutrition Vol. 63; no. 4; pp. 579 - 583
• Main Authors: O’Brien, KO, Abrams, SA, Liang, LK, Ellis, KJ, Gagel, RF
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Bethesda, MD Elsevier Inc 01.04.1996; American Society for Clinical Nutrition; American Society for Clinical Nutrition, Inc
• Subjects: Absorption; Adolescent; Amino Acids - urine; Biological and medical sciences; Bone Density; Calcium; Calcium - deficiency; Calcium - urine; Calcium Isotopes; Calcium, Dietary - administration & dosage; Calcium, Dietary - pharmacokinetics; Child; Cholecalciferol - blood; Collagen - urine; Collagen Type I; Diet; Female; Fundamental and applied biological sciences. Psychology; Girls; Humans; Metabolisms and neurohumoral controls; Osteocalcin - blood; Parathyroid Hormone - blood; Peptides - urine; Time Factors; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Water and mineral metabolism. Osmoregulation. Acidobasic balance; Human; Calcium; Homeostasis; Metabolism; Inorganic element; Preadolescent; Transitory; Feeding; Regulation(control); Absorption; Female; Nutritional status; Nutritional deficiency
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/63.4.579

Adequate calcium intake is essential for skeletal integrity, particularly during the period of peak bone mass acquisition from 9 to 17 y of age. Currently, the calcium intake of many adolescent girls is below the recommended dietary allowance. The purpose of this study was to evaluate the ability of girls to respond to acute periods of inadequate dietary calcium intake. Calcium absorption was evaluated in 11 girls aged 11.6 +/- 2.4 y after 10 d on both a low-calcium (7.05 +/- 2.03 mmol/d) and a high-calcium (35.30 +/- 2.28 mmol/d) diet. Fractional calcium absorption was determined by using oral (46Ca) and intravenous (42Ca) stable isotopes of calcium. During a low calcium intake, fractional calcium absorption was significantly greater (0.582 +/- 0.087 compared with 0.260 +/- 0.068, P < 0.0001) and urinary calcium excretion was significantly lower (1.30 +/- 0.83 compared with 3.08 +/- 1.98 mmol/d, P < 0.004) than values obtained during a high calcium intake. Concentrations of 1,25-dihydroxyvitamin D (combination of cholecalciferol and ergocalciferol) were greater during the low calcium intake, although the difference was not significant (108.7 +/- 30.6 compared with 90.0 +/- 25.1 pmol/L, P < 0.1; n = 9). Excretion of N-telopeptide was significantly greater during the low calcium intake (761 +/- 508 compared with 413 +/- 341 nmol bone collagen equivalent (BCM)/mmol creatinine, P < 0.02; n = 9), indicating that bone resorption was increased. These results suggest that during short periods of inadequate calcium intake, girls are able to significantly increase the efficiency of calcium absorption and decrease urinary calcium losses to conserve calcium required for bone mineral acquisition.