Calcium and Iron Absorption - Mechanisms and Public Health Relevance
Calcium and Iron Absorption - Mechanisms and Public Health Relevance
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DOI：
10.1024/0300-9831/a000036
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发表时间：
2010-10-01
影响因子：
2.3
通讯作者：
Loennerdal, Bo
中科院分区：
文献类型：
--
作者：
Loennerdal, Bo
对人类受试者的研究表明，钙（Ca）可以抑制铁（Fe）的吸收，无论它是作为钙盐还是在乳制品中提供。这引起了人们的关注，因为通常建议儿童和妇女增加钙的摄入量，这些人群也有缺铁的风险。然而，对人类研究的全面审查表明，长期大量增加钙摄入量的血液学指标或铁状态指标没有变化。因此，抑制作用可能持续时间短，也可能存在代偿机制。Ca和Fe之间的相互作用可能是一个内腔事件，影响铁的吸收，通过DMT 1（二价金属转运蛋白1）在顶膜。然而，也有可能在铁转移到循环过程中发生抑制，这表明丝氨酸蛋白酶输出者铁转运蛋白（FPN）和肝啡肽的作用。我们在单层培养的人肠Caco-2细胞中探索了这些可能性。铁转运（Fe-59）和表达的DMT 1，FPN，和hephaestin进行了评估后，1.5和4小时与0或100 μ M氯化钙。虽然钙并没有影响铁的吸收或DMT 1的表达在1.5小时，FPN丰度在基底外侧膜减少，导致增加细胞铁保留和减少铁流出。4小时后，DMT 1和FPN表达增加，并且膜上的FPN增加，表明反弹效应。因此，钙对铁吸收的影响可能是短期的，适应可能会随着时间的推移而发生。这可能解释了为什么对不同群体长期补充钙的研究未能显示出对铁状态的任何不利影响。
Studies on human subjects have shown that calcium (Ca) can inhibit iron (Fe) absorption, regardless of whether it is given as Ca salts or in dairy products. This has caused concern as increased Ca intake commonly is recommended for children and women, the same populations that are at risk of Fe deficiency. However, a thorough review of studies on humans in which Ca intake was substantially increased for long periods shows no changes in hematological measures or indicators of iron status. Thus, the inhibitory effect may be of short duration and there also may be compensatory mechanisms. The interaction between Ca and Fe may be a lumenal event, affecting Fe uptake through DMT1 (divalent metal transporter 1) at the apical membrane. However, it is also possible that inhibition occurs during Fe transfer into circulation, suggesting roles for the serosal exporter ferroportin (FPN) and hephaestin. We explored these possibilities in human intestinal Caco-2 cells cultured in monolayers. Iron transport (Fe-59) and expression of DMT1, FPN, and hephaestin were assessed after 1.5 and 4 hours with 0 or 100 mu M CaCl2. Although Ca did not affect Fe uptake or DMT1 expression at 1.5 hours, FPN abundance at the basolateral membrane decreased, resulting in increased cellular Fe retention and decreased Fe efflux. After 4 hours, DMT1 and FPN expression increased and there was increased FPN at the membrane, suggesting a rebound effect. Thus, the effect of Ca on Fe absorption may be of short duration and adaptation may occur with time. This may explain why studies on long-term Ca supplementation of different groups fail to show any adverse effects on Fe status.