Several iron compounds are used for fortification, including ferrous sulphate and NaFeEDTA.
The absorption profile of these may differ because of differences in their dissolution in the
gastrointestinal tract and in their interaction with dietary inhibitors of iron absorption.
As these differences might lead result in varying reactions in the blood stream, the
appearance rate of the stable iron isotope, hepcidin, non-transferrin-bound iron and total
iron in the plasma will be monitored over six hours in adult women. This is relevant as a
spike of absorbed iron may increase non-transferrin-bound iron and this could be
pro-oxidative or increase growth of pathogens. Hepcidin is a key mediator of iron absorption
and will help explain the potential differences in the plasma iron profile.
The use of stable iron isotope appearance curves to specifically detect the appearance of
small amounts of absorbed iron in the blood and distinguish between circulating body iron and
iron absorbed from the test meal was tested in a pilot study (EK 2008-23). This method is now
used in a bigger sample to test the differences in absorption profile of ferrous sulphate,
FePPi and NaFeEDTA given at fortification level with a meal.