Hallberg L, Rossander-Hultén L, Brune M, Gleerup A
Department of Medicine II and Clinical Nutrition University of Göteborg, Sahlgren Hospital, Sweden.
Eur J Clin Nutr. 1992 May;46(5):317-27.
We investigated the inhibitory effect of calcium on iron absorption in 57 human subjects. Three studies suggested that the effect is not located in the gastrointestinal tract. The presence of phytate in a meal and formation of calcium-iron-phytate complexes is not a prerequisite for the inhibition. The relative increase in iron absorption by ascorbic acid was the same in meals with and without calcium, suggesting that calcium did not influence the balance between enhancing and inhibiting ligands in the gastrointestinal lumen. No inhibiting effect on iron absorption was seen when adding 3 mg calcium to 0.01 mg iron (molar ratio Ca/Fe = 420). Previous studies showing a marked inhibition by calcium had a lower molar ratio, but greater amounts of calcium were given. This suggests that a minimal concentration of calcium is needed to achieve an effect. The present results indirectly support our original hypothesis that the inhibitory effect of calcium on iron absorption is situated within the intestinal mucosal cells. The practical nutritional implications of the inhibitory effect of calcium are considerable since addition of milk, milkshake or cheese to common meals such as pizza or hamburger meals reduced iron absorption by 50-60%. It is recommended to reduce the intake of dairy products with the main meals providing most of the dietary iron, especially for those having the highest iron requirements i.e. children, teenagers and women at childbearing age.
我们对57名受试者研究了钙对铁吸收的抑制作用。三项研究表明，该作用并非发生在胃肠道。膳食中植酸盐的存在以及钙 - 铁 - 植酸盐复合物的形成并非抑制作用的必要条件。在含钙和不含钙的膳食中，抗坏血酸使铁吸收的相对增加量相同，这表明钙不会影响胃肠道腔内促进和抑制配体之间的平衡。当向0.01毫克铁中添加3毫克钙（钙/铁摩尔比 = 420）时，未观察到对铁吸收的抑制作用。先前显示钙有显著抑制作用的研究中，钙/铁摩尔比更低，但给予的钙量更多。这表明需要最低浓度的钙才能产生作用。目前的结果间接支持了我们最初的假设，即钙对铁吸收的抑制作用发生在肠黏膜细胞内。钙抑制作用在实际营养方面的影响相当大，因为在诸如披萨或汉堡餐等常见膳食中添加牛奶、奶昔或奶酪会使铁吸收降低50 - 60%。建议在提供大部分膳食铁的主餐中减少乳制品的摄入量，特别是对于那些铁需求最高的人群，即儿童、青少年和育龄妇女。
