ABSTRACT
Objectives: Determine the duration and magnitude of the serum hepcidin (sHep) rise induced by oral iron (Fe) supplements from single and consecutive-day Fe doses and measure bioavailability in healthy subjects. Methods: Twenty six subjects (serum ferritin, SF <20 μg/L) were randomized in four groups and sHep, iron status and inflammation markers were monitored for 96 h. On day 1, no supplements were administered (control day). On days 2 and 3, subjects received iron supplements containing 40, 80, 160 and 240 mg Fe as FeSO4 in either single dose (SFe) or as two consecutive day doses (CDFe) labeled with stable iron isotopes 54FeSO4, 57FeSO4, 58FeSO4. Iron bioavailability was measured by assessing the isotopic enrichment of erythrocytic iron 14 days after stable isotope administration. Results: There was a significant effect of time of day (P<0.05) and iron dose on sHep (P<0.05). Compared to control days, sHep was significantly higher at 8h and 24h after administration for 80, 160 and 240 mg doses (P<0.05) but not for 40 mg. Iron absorption from the second CDFe dose compared to SD was not significantly decreased for 40 mg, but was decreased 37% for 80 mg, 31% for 160 mg and 45% for 240 mg (for all, P<0.01). Fractional absorption was highest from the 40 mg dose. Conclusions: In Fe-depleted women, CDFe at 80 mg or above increase sHep and this decreases iron bioavailability, while a dose of 40 mg does not. These important new data will help design optimal dosing regimens for Fe supplements in women.