Studies on iron availability in man, using stable isotope techniques

Abstract

1. Iron absorption from 10 mg Fe (as ferrous sulphate), labelled with 1.3 mg 58Fe, was measured in fasting, non-anaemic adult subjects by the faecal-balance technique. The measurement was performed twice, each subject being given, in random order, either 50 mg Fe or a placebo 18 h before the 58Fe-labelled FeSO4. 2. The 50 mg Fe load significantly reduced Fe absorption the following day (P less than 0.01), from a mean of 35.4 (SEM 4.6)% to 29.0 (SEM 5.1)%. This points to the importance of strict dietary control during Fe-absorption studies to eliminate bias in results. 3. In a separate study, the feasibility of using 58Fe-enrichment of erythrocytes, measured by neutron activation analysis (NAA), 10 d after a meal labelled with 0.69 mg 58Fe as an index of Fe absorption was examined. The levels of 58Fe in the blood were detectable by NAA. Regression analysis showed a significant relation between 58Fe-enrichment of blood and 58Fe absorption, calculated as the difference between intake and faecal excretion (R 0.59, P less than 0.05).