Effects of Inositol Tri‐, Tetra‐, Penta‐, and Hexaphosphates on <i>In Vitro</i> Estimation of Iron Availability

Abstract

ABSTRACT The effects of inositol tri‐, tetra‐, penta‐, and hexaphosphates on iron solubility were studied in vitro. Pure inositol phosphates (0.125–10 μmol) were added to 1g of freeze‐dried wheat roll and digestion was performed simulating physiological conditions. Soluble iron was used as an index of iron bioavailability. The pure inositol phosphate fractions were prepared by hydrolysis of sodium phytate and separation on anion exchange resin. The inositol phosphates were identified and quantified by HPLC. Addition of 10 μmol inositol hexa‐ and pentaphpsphate reduced iron solubility from 39% (reference) to 0.2% and 6%, respectively, while the same amount of inositol tetra‐ and tri‐phosphate slightly increased the iron solubility. Thus, degradation of inositol hexa‐ and pentaphosphates seemed to significantly reduce the inhibiting effect on iron availability.