Volume 90, Issue 3, September (2003), pp. 503-506 © The Author 2003
doi:10.1079/BJN2003931

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Short communication

Quantification of unlabelled non-haem iron absorption in human subjects: a pilot study

Jack R. Dainty¹, Mark A. Roe¹, Birgit Teucher¹, John Eagles¹, Susan J. Fairweather-Tait^1
1Institute of Food Research, Colney Lane, Norwich, NR4 7UA, , UK

 (Received 15 November 2002–Revised 17 April 2003–Accepted 10 May 2003)

A method for measuring unlabelled Fe absorption has been investigated in a pilot study using a simple mathematical model. The metabolism of newly absorbed Fe can be approximated as a single-compartment model with the sampled compartment being the plasma pool. Five female volunteers (aged 30–55 years) were recruited to participate in the pilot study. After a 10 mg oral dose of unlabelled ferrous sulfate, the change in plasma Fe concentration over the following 6 h was used to estimate the quantity of absorbed Fe from the mathematical model. To assess the accuracy of the new technique, a 1 mg oral dose of ⁵⁷Fe-labelled iron sulfate was given simultaneously with a 225 μg intravenous dose of ⁵⁸Fe as iron citrate. The plasma appearance of the labelled Fe was used to estimate the absorption of the oral label from the traditional area under the curve method. There was no significant difference (P=0·61) between the geometric mean absorption of the unlabelled (19 (−1 sd 12, +1 sd 28) %) and the labelled Fe (17 (−1 sd 10, +1 sd 29) %). These initial results are encouraging, but further work needs to be undertaken with smaller doses, as typically found in meals. The effect of diurnal variation in serum Fe concentration on the estimation of unlabelled Fe absorption needs further assessment.

Keywords:
Iron, Mathematical models, Kinetics

Abbreviations:
AUC, area under the curve, iv, intravenous