Walczyk Thomas, Davidsson Lena, Rossander-Hulthen Lena, Hallberg Leif, Hurrell Richard F
Laboratory for Human Nutrition, Institute of Food Science, Swiss Federal Institute of Technology Zürich, Rüschlikon, Switzerland.
Am J Clin Nutr. 2003 Jan;77(1):144-9. doi: 10.1093/ajcn/77.1.144.
Vitamin A and beta-carotene were recently reported to enhance iron absorption by counteracting the inhibitory effect of phytic acid in cereal-based meals and of polyphenol-containing beverages on nonheme-iron absorption in humans.
Our objective was to further evaluate the influence of vitamin A on iron absorption.
Iron absorption from corn bread with or without added vitamin A (retinyl palmitate) was determined in 5 studies in young adult human subjects by using either a stable-isotope method (2 studies) or a radioisotope technique (3 studies). Iron absorption was measured by erythrocyte incorporation of the isotopic labels and by whole-body retention of (59)Fe. Corn bread was served with water (studies 1 and 3) or coffee (studies 2, 4, and 5). The studies differed in the amounts and chemical forms of added tracer and fortification iron. The possibility of methodologic artifacts in earlier investigations was evaluated.
No effect of vitamin A on iron absorption from the test meals was identified in the individual studies by using paired Student's t test. A slightly negative effect of vitamin A on iron absorption was found with the use of analysis of variance.
The previously reported findings of a positive effect of vitamin A on nonheme-iron absorption in humans was not confirmed. Incomplete isotopic equilibration of the tracer with native iron in the meal or with fortification iron cannot explain the previous findings. However, the present study does not exclude the possibility that suboptimal vitamin A status influences the effect of dietary vitamin A on iron absorption.
最近有报道称，维生素A和β-胡萝卜素可通过抵消植酸对谷类食物中血红素铁吸收的抑制作用以及含多酚饮料对人体非血红素铁吸收的抑制作用来增强铁的吸收。
我们的目的是进一步评估维生素A对铁吸收的影响。
在5项针对年轻成年人体受试者的研究中，采用稳定同位素法（2项研究）或放射性同位素技术（3项研究）测定了添加或未添加维生素A（棕榈酸视黄酯）的玉米面包中铁的吸收情况。通过红细胞对同位素标记物的摄取以及全身对⁵⁹Fe的保留来测量铁的吸收。玉米面包搭配水（研究1和3）或咖啡（研究2、4和5）食用。这些研究在添加的示踪剂和强化铁的量及化学形式上有所不同。评估了早期研究中方法学假象的可能性。
在个体研究中，使用配对学生t检验未发现维生素A对试验餐中铁吸收有影响。使用方差分析发现维生素A对铁吸收有轻微的负面影响。
先前报道的维生素A对人体非血红素铁吸收有积极作用的研究结果未得到证实。示踪剂与餐中天然铁或强化铁的同位素平衡不完全无法解释先前的研究结果。然而，本研究并不排除维生素A状态欠佳会影响膳食维生素A对铁吸收作用的可能性。
