Iron bis-glycine chelate competes for the nonheme-iron absorption pathway.
BACKGROUND
The enterocytic absorption pathway of the food fortificant iron bis-glycine chelate has been the subject of controversy because it is not clear whether that substance uses the classic nonheme-iron absorption pathway or a pathway similar to that of heme absorption.


OBJECTIVE
The objective was to study the absorption pathway of iron bis-glycine chelate in human subjects.


METHODS
Eighty-five healthy adult women were selected to participate in 1 of 6 iron-absorption studies. Study A involved the measurement of the dose-response curve of the absorption of ferrous sulfate (through a nonheme-iron absorption pathway); study B involved the competition of iron bis-glycine chelate with ferrous sulfate for the nonheme-iron absorption pathway; study C involved the measurement of the dose-response curve of heme-iron absorption; study D involved the competition of iron bis-glycine chelate with hemoglobin for the heme-iron absorption pathway; and studies E and F were the same as studies A and B, except that the iron bis-glycine chelate was encapsulated in enteric gelatin capsules so that it would not be processed in the stomach.


RESULTS
Iron from the bis-glycine chelate competed with ferrous sulfate for the nonheme-iron absorption pathway. Iron from the bis-glycine chelate also competed with ferrous sulfate for absorption when liberated directly into the intestinal lumen. Iron from the bis-glycine chelate did not compete with heme iron for the heme-iron absorption pathway.


CONCLUSIONS
The iron from iron bis-glycine chelate delivered at the level of the stomach or duodenum becomes part of the nonheme-iron pool and is absorbed as such.
Institute of Nutrition and Food Technology, the University of Chile, Santiago. fpizzaro@uec.inta.uchile.cl
Fernando
F
Pizarro
Manuel
M
Olivares
Eva
E
Hertrampf
Dora I
DI
Mazariegos
Miguel
M
Arredondo
Angélica
A
Letelier
Virginia
V
Gidi
D000042:Absorption; D000328:Adult; D001667:Binding, Competitive; D001682:Biological Availability; D005260:Female; D005296:Ferrous Compounds / Q000008:administration & dosage / Q000378:metabolism / Q000493:pharmacokinetics*; D005998:Glycine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000378:metabolism / Q000493:pharmacokinetics*; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007408:Intestinal Absorption; D007501:Iron / Q000008:administration & dosage / Q000493:pharmacokinetics*; D007502:Iron Chelating Agents / Q000493:pharmacokinetics; D009752:Nutritional Status
D005296:Ferrous Compounds; D006454:Hemoglobins; D007502:Iron Chelating Agents; C073588:bis-glycino iron II; C020748:ferrous sulfate; D007501:Iron; D005998:Glycine