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Heme Iron
Iron bound within a porphyrin ring in hemoglobin and myoglobin from animal flesh, absorbed via the HCP1/HRG-1 pathway with bioavailability of approximately 15-35%, largely independent of other dietary factors.
Heme iron from meat, poultry, and fish is more efficiently absorbed than nonheme iron and is not subject to inhibition by phytate, polyphenols, or calcium. After enterocyte uptake, heme is cleaved by heme oxygenase to release Fe2+ into the same intracellular pool as nonheme iron, where it is regulated by hepcidin/ferroportin. Heme iron also enhances absorption of nonheme iron consumed in the same meal ("meat factor").
How one textbook covers it
Modern Nutrition in Health and Disease, 12th ed. — Ch 10: Iron
Heme iron from meat, poultry, and fish is more efficiently absorbed than nonheme iron and is not subject to inhibition by phytate, polyphenols, or calcium. After enterocyte uptake, heme is cleaved by heme oxygenase to release Fe2+ into the same intracellular pool as nonheme iron, where it is regulated by hepcidin/ferroportin. Heme iron also enhances absorption of nonheme iron consumed in the same meal ("meat factor").
Related terms
Hepcidin, Iron deficiency anemia, Nonheme iron