Iron metabolism and absorption

Abstract

Iron is an essential nutrient for animals living in an oxygen-rich environment. It greatly enhances the oxygen-carrying capacity of aqueous solutions as the active center in hemoglobin, facilitating oxygen delivery to tissues. Because it accepts and loses electrons readily, iron confers redox activity on the cytochromes of the respiratory chain and on numerous other enzymes. Yet, its utility is balanced by a risk of toxicity. Free iron catalyzes the formation of free radicals that damage cell membranes, proteins and DNA. To exploit the useful properties of iron, while avoiding its toxicity, most living organisms have developed meticulously regulated mechanisms for iron transport and storage. Specialized proteins sequester extracellular and intracellular iron and mediate transport of iron across cellular membranes. Iron balance is regulated by systemic homeostatic mechanisms that we are only beginning to understand. This review describes our current understanding of iron metabolism in mammals.