Overview of the zinc absorption mechanism for improving zinc nutrition

抄録

Zinc is an essential trace element with various physiological functions; it is a structural, catalytic, and signaling component of proteins. Owing to its wide range of functions, zinc deficiency causes various symptoms, such as taste disorders, dermatitis, hair loss, decreased appetite, growth disorders, and gonad dysfunction. The global prevalence of zinc deficiency is estimated to be about 25%; thus, its prevention is important for human health. Approximately 2–3 g of zinc is present in the adult human body. Systemic zinc homeostasis is regulated by the zinc transporters ZIP4 and ZNT1, which play major roles in regulating the absorption of food-derived zinc, primarily in the duodenum and jejunum. ZIP4 is expressed on the apical membrane of intestinal epithelial cells and allows divalent zinc ions to enter cells from the lumen. Zinc in enterocytes is subsequently transported by ZNT1 on the basolateral membrane into the portal vein, where it binds to albumin and α2-macroglobulin. In turn, zinc regulates the expression of ZIP4 and ZNT1. This review briefly describes the mechanism of dietary zinc absorption, focusing on zinc in foods and the transporters involved in zinc absorption in the intestinal tract. Moreover, we discuss the potential of dietary components to increase the efficiency of zinc absorption in the intestinal tract via zinc transporters and improve zinc nutrition.