Iron absorption from ferrous fumarate in adult women is influenced by ascorbic acid but not by Na 2 EDTA

Abstract

Ascorbic acid and Na 2 EDTA enhance Fe absorption from the water-soluble Fe compound FeSO 4 but their effect on poorly water-soluble Fe compounds such as ferrous fumarate is less well established. In the present study, the effects of ascorbic acid and Na 2 EDTA on Fe absorption from ferrous fumarate were evaluated in adult women (ten women/study) from the erythrocyte incorporation of Fe stable isotopes ( 57 Fe or 58 Fe) 14 d after administration. Two separate studies were made with test meals of Fe-fortified infant cereal (5 mg Fe/meal). Data were evaluated by paired t tests and the results are presented as geometric means. In study 1a, the comparison between Fe absorption from ferrous fumarate- and FeSO 4 -fortified cereal showed that adult women absorb Fe as well from ferrous fumarate as from FeSO 4 (3·0 and 3·1 % respectively, P =0·85). After addition of Na 2 EDTA (Na 2 EDTA:fortification Fe molar ratio of 1:1), Fe absorption from FeSO 4 was significantly higher than from ferrous fumarate (5·3 v . 3·3 % respectively, P <0·01; study 1b). In study 2, Fe absorption was compared from ferrous fumarate-fortified meals with and without ascorbic acid added at a 4:1 molar ratio (relative to fortification Fe) and the results showed that ascorbic acid increased Fe absorption from ferrous fumarate significantly (6·3 v . 10·4 %, P =0·02). The results of the present studies show that Fe absorption from ferrous fumarate is enhanced by ascorbic acid but not by Na 2 EDTA, thus emphasising that not all findings from Fe absorption studies made with FeSO 4 can be extrapolated to Fe compounds with different solubility properties.