EFFECTS OF DOUBLE-BLIND CONTROLLED CALCIUM SUPPLEMENTATION ON CALCIUM-ABSORPTION IN CHINESE CHILDREN MEASURED WITH STABLE ISOTOPES (CA-42 AND CA-44)

A double-blind controlled Ca supplementation trial was conducted for 6 months in thirty-four 7-year-old Chinese children from Hongkong and J iangmen, China. The children were randomly allocated to the study grou p (n 17) or control group (n 17), and a CaCO3 tablet (300 mg Ca) or a placebo tablet was taken daily, True fractional Ca absorption (TFCA) w as evaluated before and after the trial using stable isotopes: 8 mg Ca -44 mixed in 100 g chocolate milk was given after an intravenous injec tion of 0.75 mg Ca-42, There was no significant difference in baseline TFCA between the study group (60.6 (SD 11.4)%) and the controls (58.2 (SD 9.0)%; P = 0.55), Serum 25-hydroxycholecalciferol levels were com parable between the two groups (P = 0.71). After 6 months, TFCA of the study group (55.6 (SD 12.7)%) was significantly lower than that of th e controls (64.3 (SD 10.7)%; P = 0.015), By comparing the individual c hanges in TFCA after the trial between the two groups there was a nons ignificant reduction in TFCA (5.03 (SD 12.4)%; P = 0.11, Wilcoxon sign ed-rank test) in the study group (60.6-55.6%), whereas a significant i ncrease in TFCA (6.17 (SD 7.7)%; P = 0.004, Wilcoxon signed-rank test) was observed in the controls (58.2-64.3%), The differential in TFCA b etween the two groups after 6 months was significantly different (P = 0.001), and remained significant after adjustment for baseline dietary intakes, weight and height by multiple-regression analysis (P = 0.003 ), If the mechanism of TFCA from chocolate milk in response to the tre atment effects is similar to that from the total diet, then our result s suggest that children with adequate vitamin D status can adapt to a change in Ca intake by adjusting the efficiency of TFCA. In corollary, children on habitually-low Ca diets have a higher TFCA than the count erparts with higher Ca diets.