Mechanisms and regulation of intestinal uptake and transfer of iron

Despite much research over the past fifty years, the precise details of intestinal iron absorption remain unclear. The lack of understanding extends both to the specific biochemical mechanisms of transport as well as the means by which these are regulated. Iron in several dietary forms must be digested and processed in the intestinal lumen, taken up across the mucosal brush border membrane, transported through the intestinal absorptive cell, accomplish a second transmembrane passage across the basolateral membrane and, finally, be transported to sites of iron metabolism and storage within the body. Recent findings in several of these areas are reviewed. Evidence is presented to support the involvement, or non-involvement, of several intestinal iron-binding components in iron transport. In the future, the application of molecular biology to the investigation of intestinal iron metabolism will undoubtedly increase understanding of absorption mechanisms and their regulation.