TRUE FRACTIONAL CALCIUM-ABSORPTION IN CHINESE CHILDREN MEASURED WITH STABLE ISOTOPES (CA-42 AND CA-44)

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 (n 22) and Jiangmen (n 12) participated in the study, An oral administration of 8 mg Ca-44 in 100 g chocolate milli. was given shortly after an intravenous injection of 0.75 mg Ca-42, 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 less than or equal to 500 mg/d, n 19) with mean Ca intake 359 mg/d was 63.1 (so 10.7)% and that of a higher-Ca-intake group (Ca > 500 mg/d, n 15) with mean Ca intake 862 mg/d was 54.8 (so 7.3)%; the difference in TFCA was significant (P = 0.016), Serum levels of 25-hydroxycholecalciferol of the children were adequate (33.7 (so 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.