Phytic Acid Degradation as a Means of Improving Iron Absorption

Abstract

Phytic acid is a potent inhibitor of native and fortification iron absorption and low absorption of iron from cereal- and/or legume-based complementary foods is a major factor in the etiology of iron deficiency in infants. Dephytinization of complementary foods or soy-based infant formulas is technically possible but, as phytic acid is strongly inhibitory at low concentrations, complete enzymatic degradation is recommended. If this is not possible, the phytic acid to iron molar ratio should be decreased to below 1:1 and preferably below 0.4:1. Complete dephytinization of cereal- and legume-based complementary foods has been shown to increase the percentage of iron absorption by as much as 12-fold (0.99% to 11.54%) in a single-meal study when the foods were reconstituted with water. The addition of milk, however, inhibits iron absorption and overcomes the enhancing effect of phytic acid degradation. Dephytinization can therefore be strongly recommended only for cereal/legume mixtures reconstituted with water, especially low-cost complementary foods destined for infants in developing countries. In countries where infant cereals are consumed with milk, ascorbic acid addition can more easily be used to overcome the negative effect of phytic acid on iron absorption. Similarly with soy-based infant formulas, especially if manufactured from low-phytate isolates, ascorbic acid can be used to ensure adequate iron absorption.