Food Iron Absorption in Man — III: Effect of Iron Salt, Ascorbic Acid and Desferrioxamine on the Isotopic Exchange between Native Food Iron and an Extrinsic Inorganic Iron Tracer

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Abstract
A new two pool extrinsic tag method to measure the dietary iron absorption has recently been proposed. One of the main prerequisites for this method is that a complete isotopic exchange takes place in the soluble ionized part of the common non‐haeme iron pool.The present investigation was carried out to test the validity of using this method to measure the effect of substances promoting or inhibiting dietary non‐haeme iron absorption.Normal subjects were served a meal prepared from biologically 55Fe labelled wheat or maize with added inorganic iron labelled with 59Fe. When served with added ferrous sulphate or ascorbic acid equal absorptions from the two tracers were found. When served with desferrioxamine there was a marked and almost equal reduction of the absorption from the two radioiron tracers. It is concluded that the rate or extent of isotopic exchange is not affected by compounds increasing (ferrous sulphate or ascorbic acid) or decreasing (desferrioxamine) the size of the ionized and/or soluble part of the common non‐heame iron pool.The extrinsic tag method can thus be used to study the effect of iron fortification or of substances promoting or inhibiting the absorption of dietary non‐haeme iron.