Lee W T, Leung S S, Xu Y C, Wang S H, Zeng W P, Lau J, Fairweather-Tait S J
Department of Paediatrics, Faculty of Medicine, Chinese University of Hongkong.
Br J Nutr. 1995 Feb;73(2):311-21. doi: 10.1079/bjn19950032.
A double-blind controlled Ca supplementation trial was conducted for 6 months in thirty-four 7-year-old Chinese children from Hongkong and Jiangmen, China. The children were randomly allocated to the study group (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) was evaluated before and after the trial using stable isotopes: 8 mg 44Ca mixed in 100 g chocolate milk was given after an intravenous injection of 0.75 mg 42Ca. 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 comparable 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 the controls (64.3 (SD 10.7)%; P = 0.015). By comparing the individual changes in TFCA after the trial between the two groups there was a non-significant reduction in TFCA (5.03 (SD 12.4)%; P = 0.11, Wilcoxon signed-rank test) in the study group (60.6-55.6%), whereas a significant increase 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 between 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 treatment effects is similar to that from the total diet, then our results 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 counterparts with higher Ca diets.
对来自中国香港和江门的34名7岁中国儿童进行了一项为期6个月的双盲对照钙补充试验。这些儿童被随机分为研究组（n = 17）或对照组（n = 17），每天服用一片碳酸钙片（含300毫克钙）或一片安慰剂。在试验前后使用稳定同位素评估真实钙分数吸收（TFCA）：静脉注射0.75毫克42Ca后，给予100克巧克力牛奶中混合的8毫克44Ca。研究组（60.6（标准差11.4）%）和对照组（58.2（标准差9.0）%；P = 0.55）的基线TFCA无显著差异。两组的血清25-羟基胆钙化醇水平相当（P = 0.71）。6个月后，研究组的TFCA（55.6（标准差12.7）%）显著低于对照组（64.3（标准差10.7）%；P = 0.015）。通过比较两组试验后TFCA的个体变化，研究组（60.6 - 55.6%）的TFCA有不显著的降低（5.03（标准差12.4）%；P = 0.11，Wilcoxon符号秩检验），而对照组（58.2 - 64.3%）观察到TFCA有显著增加（6.17（标准差7.7）%；P = 0.004，Wilcoxon符号秩检验）。6个月后两组之间的TFCA差异显著（P = 0.001），在通过多元回归分析对基线饮食摄入量、体重和身高进行调整后仍显著（P = 0.003）。如果巧克力牛奶中TFCA对治疗效果的反应机制与总饮食中的相似，那么我们的结果表明，维生素D状态充足的儿童可以通过调整TFCA的效率来适应钙摄入量的变化。相应地，习惯性低钙饮食的儿童比高钙饮食的儿童有更高的TFCA。
