True fractional calcium absorption in Chinese children measured with stable isotopes (42Ca and 44Ca)

Warren T. Lee, Sophie S. F. Leung , Susan J. Fairweather-Tait, Dora M. Y. Leung, Heidi S. Y. Tsang, John Eagles, Tom Fox, S. H. Wang, Y. C. Xu, W. P. Zeng, Joseph Lau, J. R. L. Maseri

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Abstract

True fractional Ca absorption (TFCA) was compared in children with different habitual Ca intakes using a double-label stable-isotope technique. Chinese children aged 7 years from Hongkong (n22) and Jiangmen (n12) participated in the study. An oral administration of 8 mg 44Ca in 100 g chocolate milk was given shortly after an intravenous injection of 0.75 mg 42Ca. Ca isotopic ratios were determined in urine samples collected 24 h later using thermal-ionization mass spectrometry. There was no significant difference in TFCA between Jiangmen and Hongkong children (P = 0.16). TFCA of a lower-Ca-intake group (Ca 500 mg/d, n15) with mean Ca intake 862 mg/d was 54.8 (SD 7.3)%; the difference in TFCA was significant (P = 0.016). Serum levels of 25-hydroxycholecalciferol of the children were adequate (33.7 (SD 7.7) ng/ml). The present study indicates that growing children accustomed to a low-Ca diet appear to be able to enhance their absorptive capacity. If it is assumed that dietary Ca absorption by Chinese children resembles their TFCA from a single meal of chocolate milk, then the recommended dietary allowance (RDA) for Ca for Chinese children would be lower than the US RDA (800 mg/d), which is based on an estimated 40% Ca absorption as reported for Caucasian children. A comparative absorption study is necessary to determine whether there is any difference in TFCA between Caucasian and Chinese children.
Original languageEnglish
Pages (from-to)883-897
Number of pages15
JournalBritish Journal of Nutrition
Volume72
Issue number6
DOIs
Publication statusPublished - Dec 1994

Keywords

  • Body Height
  • Body Weight
  • Calcifediol
  • Calcium
  • Calcium Isotopes
  • Child
  • China
  • Diet
  • Female
  • Humans
  • Intestinal Absorption
  • Male
  • Mass Spectrometry

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