Iron absorption from ferrous fumarate in adult women is influenced by ascorbic acid but not by Na2EDTA

Ascorbic acid and Na2EDTA enhance Fe absorption from the water-soluble Fe compound FeSo4 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 Na2EDTA 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 ^58Fe) 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 la, the comparison between Fe absorption from ferrous fumarate- and FeSo4-fortified cereal showed that adult women absorb Fe as well from ferrous fumarate as from FeSC)4 (3.0 and 34 % respectively, P= 0.85). After addition of Na2EDTA (Na2EDTA:fortification Fe molar ratio of 1:1), Fe absorption from FeSC)4 was significantly higher than from ferrous fumarate (5.3 (nu). 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 (nu). 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 Na2EDTA, thus emphasising that not all findings from Fe absorption studies made with FeSo4 can be extrapolated to Fe compounds with different solubility properties.