Background: Calcium inhibits and ascorbic acid (AA) enhances iron absorption from iron-fortified foods. Absorption efficiency depends on iron status, although the interaction is unclear. Objective: We investigated the ability of AA to overcome calcium-induced inhibition of iron absorption in children differing in iron status. Methods: The effect of calcium (0, 100, and 200 mg/test meal) on iron absorption in the absence and presence of AA (0, 42.5, and 85 mg/test meal) from a casein/whey-based drink fortified with ferrous sulfate was assessed in a series of randomized crossover studies both in iron-replete (IR) Indian schoolchildren and in children with iron deficiency anemia (IDA) (6-11 γ n = 14-16/group) by using stable isotopes. Results: In the absence of calcium and AA, iron absorption from the casein/whey-based drink was 20% lower in IR children than in children with IDA. The addition of calcium reduced mean iron absorption by 18-27%, with the effect being stronger for high added calcium (P < 0.01). AA at a 2:1 or 4:1 molar ratio enhanced iron absorption by a factor of 2-4 and greatly overcompensated for the inhibitory effect of calcium on iron absorption in a dose-dependent manner (P < 0.001). The dose-response effect tended to be stronger (P < 0.1) in the IDA group, and iron status was of far less influence on iron absorption than the enhancing effect of AA. Conclusion: When adding AA to iron-fortified milk products, care should be taken not to provide absorbable iron in excess of needs.
CITATION STYLE
Walczyk, T., Muthayya, S., Wegmüller, R., Thankachan, P., Sierksma, A., Frenken, L. G. J., … Hurrell, R. F. (2014). Inhibition of Iron Absorption by Calcium Is Modest in an Iron-Fortified, Casein- and Whey-Based Drink in Indian Children andIs Easily Compensated for by Addition of Ascorbic Acid. Journal of Nutrition, 144(11), 1703–1709. https://doi.org/10.3945/jn.114.193417
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