Role of gastric acid in food iron absorption.
Radioiron absorption tests in human volunteers demonstrated a modest but significant 28% reduction in the absorption of dietary nonheme iron from a meal that was preceded by the administration of 300 mg cimetidine. More pronounced decreases of 42% and 65% were observed with 600 and 900 mg cimetidine, respectively. Antacid caused a 52% decrease in iron absorption whereas pentagastrin had no significant effect. Since 300 mg cimetidine reduces gastric acid secretion by 60%-80% but iron absorption by only 28%, it appears that under normal conditions more gastric acid is secreted than is required for optimal iron absorption; absorption falls only when acid secretion is markedly reduced. Cimetidine in the doses currently recommended would not be expected to have a major effect on iron nutrition, although the combination of high doses of cimetidine with antacids would impair nonheme iron absorption significantly.
D000042:Absorption; D000293:Adolescent; D000328:Adult; D000863:Antacids / Q000494:pharmacology; D002927:Cimetidine / Q000008:administration & dosage / Q000494:pharmacology; D004032:Diet; D005260:Female; D005744:Gastric Acid / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D007501:Iron / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010418:Pentagastrin / Q000494:pharmacology
D000863:Antacids; D002927:Cimetidine; D007501:Iron; D010418:Pentagastrin