True fractional calcium absorption in Chinese children measured with stable isotopes (42Ca and 44Ca).
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 < or = 500 mg/d, n19) with mean Ca intake 359 mg/d was 63.1 (SD 10.7)% and that of a higher-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.
Lee
W T
WT
Department of Paediatrics, Faculty of Medicine, Chinese University of Hongkong, Shatin.
Leung
S S
SS
Fairweather-Tait
S J
SJ
Leung
D M
DM
Tsang
H S
HS
Eagles
J
J
Fox
T
T
Wang
S H
SH
Xu
Y C
YC
Zeng
W P
WP
D001827:Body Height; D001835:Body Weight; D002112:Calcifediol / Q000097:blood; D002118:Calcium / Q000378:metabolism* / Q000652:urine; D002127:Calcium Isotopes; D002648:Child; D002681:China / Q000208:ethnology; D004032:Diet; D005260:Female; D006801:Humans; D007408:Intestinal Absorption; D008297:Male; D013058:Mass Spectrometry
D002127:Calcium Isotopes; D002112:Calcifediol; D002118:Calcium