Iron absorption from ferrous bisglycinate and ferric trisglycinate in whole maize is regulated by iron status

Background: There is a need to determine whether iron absorption from iron amino acid chelates is protected from inhibition by dietary phytate and regulated normally by iron status. Objective: The objective of this study was to compare iron absorption from ferrous sulfate ferrous bisglycinate and ferric trisglycinate in whole-maize meal; to determine whether iron from ferrous bisglycinate and ferrous sulfate exchanges in the intestinal pool; and to assess iron absorption from ferrous bisglycinate and ferric trisglycinate over a range of iron statuses. Design: In study 1A 10 iron-sufficient men consumed ferrous sulfate-fortified whole maize meal porridge equilibrated with (59)Fe-sulfate on day 1 and (55)Fe-bisglycinate on day 2. In study 1B these volunteers consumed ferrous sulfate-fortified porridge equilibrated with (59)Fe-sulfate and (55)Fe-bisglycinate simultaneously. In studies 2A and 2B iron absorption from 3 mg Fe as (59)Fe-ascorbate (55)Fe-bisglycinate or (59)Fe-trisglycinate in water and in porridge was compared in 23 subjects with a range of iron statuses. Iron absorption was determined from blood radioactivity on day 16. Results: In study 1A geometric mean iron absorption from ferrous bisglycinate was 6.0% (range: 2.6 - 13.6%) 4 times higher than that from ferrous sulfate (1.7%; range: 1.0-3.3%; P