Lönnerdal B, Sandberg A S, Sandström B, Kunz C
Department of Nutrition, University of California, Davis 95616.
J Nutr. 1989 Feb;119(2):211-4. doi: 10.1093/jn/119.2.211.
While it is known that phytic acid, inositol hexaphosphate, has a negative effect on zinc and calcium absorption, the effects of inositol which is phosphorylated to a lesser extent are less known. We have prepared inositol triphosphate (IP-3), tetraphosphate (IP-4), pentaphosphate (IP-5) and hexaphosphate (IP-6) by hydrolysis of sodium phytate and separation by ion-exchange chromatography and have studied their effect on zinc and calcium absorption. Using a suckling rat pup model, we found that liver uptake of 65Zn after 6 h was 5% of the total dose from solutions of IP-6, 19% from IP-5, 28% from IP-4, 29% from IP-3 and 31% from ZnCl2 (control). Non-absorbed calcium was 17%, 1.4%, 0.5%, 0.5% and 0.5% of the given dose of 45Ca, respectively. Thus, at a high degree of phosphorylation (IP-6, IP-5), zinc and calcium uptake was inhibited, while no effect was observed for the other phosphates. Consequently, total "phytate" analysis, which includes inositol phosphates with varying degrees of phosphorylation, can give misleading information with regard to mineral availability. In addition, even limited dephosphorylation of inositol hexaphosphate can have a positive effect on mineral absorption.
虽然已知植酸（肌醇六磷酸）对锌和钙的吸收有负面影响，但磷酸化程度较低的肌醇的影响则鲜为人知。我们通过植酸钠水解和离子交换色谱分离制备了肌醇三磷酸（IP - 3）、四磷酸（IP - 4）、五磷酸（IP - 5）和六磷酸（IP - 6），并研究了它们对锌和钙吸收的影响。使用乳鼠幼崽模型，我们发现6小时后肝脏对65Zn的摄取量分别为：来自IP - 6溶液的占总剂量的5%，来自IP - 5的占19%，来自IP - 4的占28%，来自IP - 3的占29%，来自ZnCl2（对照）的占31%。未吸收的钙分别占所给45Ca剂量的17%、1.4%、0.5%、0.5%和0.5%。因此，高度磷酸化（IP - 6、IP - 5）时，锌和钙的摄取受到抑制，而其他磷酸盐则未观察到影响。因此，包括不同磷酸化程度的肌醇磷酸酯的总“植酸”分析，在矿物质可利用性方面可能会给出误导性信息。此外，即使肌醇六磷酸的去磷酸化程度有限，也可能对矿物质吸收产生积极影响。
