Rice fortification technologies may affect mineral bioavailability from fortified rice.We measured fractional iron (FAFe, Studies 1 & 2) and zinc (FAZn, Study 2) absorption from ferric-pyrophosphate (FePP) and zinc-oxide (ZnO) fortified rice produced with coating, hot or cold extrusion.
Healthy women were fed rice-meals (both studies: 4 mg iron/meal): Study 1 compared FAFe from hot (HE) versus cold (CE) extruded FePP-fortified rice (n=19); Study 2 compared FAFe and FAZn from hot extruded (HOR) versus coated (COR) FePP-fortified rice, and FAFe versus non-fortified extruded rice with FeSO4 (reference) added after cooking (n=22). Study 1 used citric-acid (CA) as chelating-agent for iron, Study 2 used CA and trisodium-citrate (TSC). FAFe was measured as erythrocyte-incorporation of stable iron isotopes 14 days after meal-administration and corrected to a serum ferritin level of 40 µg/l (FAFecorr). FAZn was assessed via double-isotope urinary-monitoring.
FAFecorr (-SD, +SD) was higher from CE: 1.8% (1.0, 3.4%) than from HE: 1.1% (1.0, 3.0%; P=.029); there was no significant difference in FAFe between HOR: 3.6% (1.5, 9.0%) and COR: 2.8% (1.4, 5.8), however, COR had a lower FAFecorr than the reference meal: 4.6%, (2.4, 8.9%) (P=.001). FAZn (-SD, +SD) did not differ between HOR: 9.9% (6.3, 15.7) and COR 10.0% (7.7, 12.3; n.s.).
Iron absorption from FePP-fortified rice is affected both by iron chelators and fortification technology. We found no difference for FAFecorr and FAZn between hot extruded and coated rice when CA/TSC was present. Cold extruded rice containing CA only, showed increased FAFecorr compared to hot extruded rice.