Iron absorption and bioavailability: An updated review

Regulation of iron absorption operates at the level of duodenal mucosal cells. Despite much research, the specific biochemical pathways of iron absorption and the regulatory mechanisms controlling it remain unknown. This review summarizes current knowledge of and hypotheses on each of the three steps of iron absorption: uptake from the intestinal lumen into mucosal cells, transit through the cell, and release from the cells into the body. Absorption may be defined as the movement of iron from the intestinal lumen across the epithelial cells of the digestive tract into the circulation, while bioavailability generally refers to the proportion of iron in a given food or diet that the body can actually utilize. The most common technique of measuring iron absorption and bioavailability, extrinsic radiolabeling of a single meal, is discussed in the context of the latest studies using this methodology. (C) 1998 Elsevier Science Inc.