Absorption Mechanisms of Iron, Copper, and Zinc: An Overview

Essential trace elements play pivotal roles in numerous structural and catalytic functions of proteins. Adequate intake of essential trace elements from the daily diet is indispensable to the maintenance of health, and their deficiency leads to a variety of conditions. However, excessive amounts of these trace elements may be highly toxic, and in some cases, may cause damage by the production of harmful reactive oxygen species. Homeostatic dysregulation of their metabolism increases the risk of developing diseases. Specific transport proteins that facilitate influx or efflux of trace elements play key roles in maintaining the homeostasis. Recent elucidation of their crucial functions significantly facilitated our understanding of the molecular mechanisms of iron (Fe), copper (Cu), and zinc (Zn) absorption in the small intestine. This paper summarizes their absorption mechanisms, with a focus on indispensable functions of the molecules involved in it, and briefly discusses the mechanisms of homeostatic control of each element at the cellular and systemic levels.