Shanghai Jiao Tong University, School of Medicine, Xin-Hua Hospital, Department of Child and Juvenile Health Care, Shanghai, China.
Int J Vitam Nutr Res. 2009 Jul;79(4):230-7. doi: 10.1024/0300-9831.79.4.230.
Extrinsic labeling techniques are typically used to measure fractional absorption of zinc (FAZ(extrinsic)) but none have been adequately evaluated.
To compare determination of the quantity of zinc absorbed (TAZ(extrinsic)) using measurements of FAZ(extrinsic) with results of simultaneous determinations of dietary zinc absorbed (TAZ(metabolic)) that are not dependent on labeling ingested food with an extrinsic tracer (modified metabolic balance technique).
(70)Zn was administered orally with all meals for 6 consecutive days to 21 healthy, free-living adult women consuming a constant diet. (68)Zn and (67)Zn were administered intravenously. FAZ(extrinsic) was measured using a dual isotope tracer ratio technique and multiplied by dietary zinc to give TAZ(extrinsic). TAZ(metabolic) was determined by addition of net absorption of zinc and endogenous fecal zinc, the latter determined by an isotope dilution technique.
TAZ(extrinsic) and TAZ(metabolic) were 3.0 +/- 1.1 mg/day and 3.1 +/- 1.1 mg/day respectively, paired t-test p = 0.492. The correlation coefficient for TAZ(extrinsic) and TAZ(metabolic) was 0.91, and for FAZ(extrinsic) and FAZ(metabolic) was 0.95. A Bland Altman analysis indicated a bias of 0.07, and the limits of agreement of -0.86 to 1.01 for TAZ(extrinsic) and TAZ(metabolic).
These results from two independent methods provide reasonable validation of our extrinsic labeling technique for a wide range of composite diets.
外源性标记技术通常用于测量锌的分数吸收（FAZ（外源性）），但尚未得到充分评估。
比较使用外源性标记技术测量的 FAZ（外源性）来确定吸收的锌量（TAZ（外源性））与不依赖于外源性示踪剂标记摄入食物的同时测定饮食中吸收的锌量（TAZ（代谢））的结果，使用改良代谢平衡技术。
连续 6 天，给 21 名健康、自由生活的成年女性食用常量饮食，每餐口服 70Zn，并连续 6 天给予 68Zn 和 67Zn 静脉注射。使用双同位素示踪剂比技术测量 FAZ（外源性），并将其乘以饮食中的锌量以得出 TAZ（外源性）。通过添加锌的净吸收和内源性粪便锌来确定 TAZ（代谢），后者通过同位素稀释技术确定。
TAZ（外源性）和 TAZ（代谢）分别为 3.0 ± 1.1 mg/天和 3.1 ± 1.1 mg/天，配对 t 检验 p = 0.492。TAZ（外源性）和 TAZ（代谢）的相关系数为 0.91，FAZ（外源性）和 FAZ（代谢）的相关系数为 0.95。Bland Altman 分析表明存在 0.07 的偏差，TAZ（外源性）和 TAZ（代谢）的一致性界限为-0.86 至 1.01。
这两种独立方法的结果为我们的外源性标记技术在广泛的复合饮食中提供了合理的验证。
