同位素示踪法测定儿童铁的吸收率

目的:研究农村代表性膳食条件下儿童铁的吸收率。方法:采用天然低丰度稳定性同位素Fe标记FeSO4,以稀土元素镝(Dy)作为排泄物回收标记物。自愿受试者为4～6岁身体健康的农57村儿童。采用山东农村代表性膳食模式。同位素标记铁与Dy以饼干为载体分两天三餐前经口给予。实验期间每日留取受试者膳食样品并收集受试者在实验期的粪便,采用原子吸收(AAS)和热电离质谱(TIMS)分别检测膳食和粪便中总铁含量与Fe/56Fe比值,计算铁的吸收率。同时对脂肪、瘦肉、57蛋白、植酸、纤维素和VC的日摄入量进行测定,并将结果与我国每日营养推荐膳食供给量(DRI)比较。结果:铁的吸收率(%)为6.06±2.24,远低于1988年我国修订推荐RDA所参考国外的10%,铁的平均日摄入量为10.29mg,占DRI的102.9%,其中血红素铁平均日摄入量占总铁日摄入量的17.49%,基本达到推荐量。蛋白质和抗坏血酸的日摄入量仅占DRI的56.73%和29.60%远低于推荐量。脂肪、植酸和膳食纤维的摄入量较高。结论:按目前山东农村的膳食模式,儿童铁日摄入量已达推荐量,但吸收率偏低,因而铁摄入量仍不足。蛋白质和抗坏血酸的日摄入量较低。

STUDY ON IRON ABSORPTION RATE IN CHILDREN BY STABLE ISOTOPE TECHNIQUE

Objective: To study the iron absorption in 10 healthy children from Shandong rural region. Methods: Stable iron 57Fe was used as tracer to label FeSO4. Dy was used as a marker of iron recovery. The diet used in the study was based on the typical dietary pattern of Shandong rural region. 57FeSO4 and Dy were first added to the biscuit, and administered orally three times a day in two days. The diet and feces samples of subjects were collected for 12 consecutive days. AA and TIMS were used for determination of iron and stable iron isotope concentration in food and feces samples, and the iron absorption was calculated. The daily intake of iron, protein, fat, vitamin C, phytic acid and dietary fiber were determined, and compared with DRI. Results: The absorption rate of iron was(6.06±2.24)%, much lower than 10% in the west countries. The daily intake of iron was 10.29 mg, about 102.9% of DRI. The intakes of protein and VC were only 56.73% and 29.60% of DRI respectively. The intakes of fat, phytic acid and dietary fiber were relatively high. Conclusion: Under the actual dietary pattern of Shandong rural region, although the daily intake of iron has already reached DRI, the healthy children still have shortage of iron intake, due to poor iron absorption rate. Key word: stable isotope;iron;absorption rate;children