The Significance of Iron, Zinc and Selenium for Human Nutrition - Metabolism, Function and Requirements
- 12.10.2010
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- Redaktion
Jan Philipp Schuchardt, Andreas Hahn, Hannover
Iron is quantitatively the most important trace element in the human body. The bioavailability of haem iron from food of animal origin is clearly superior to that of non-haem iron of plant origin.Endogenous iron levels are closely regulated in a complex control mechanism. The adjustment of intestinal absorption plays a central role in this mechanism. Iron is involved in the transport and storage of oxygen as a component of haemoglobin and myoglobin, respectively. Due to its ability to change valence, iron is likewise involved in a variety of redox reactions as part of diverse enzymes. The recommended iron intake is 10 mg/d for male and non-menstruating females, while for menstruating females in childbearing age an intake of 15 mg/d is recommended to compensate for iron loss.
In Germany, the supply situation of menstruating woman is thought to be suboptimal. Latent iron deficiency with depleted iron stores is highly prevalent in this population. The absorption of zinc and selenium is carried out by a variety of mechanisms, some of them specific. As with other minerals, the bioavailability and absorption of zinc and selenium is inhibited or promoted by specific food ingredients. Zinc homeostasis is maintained through a balance between intestinal absorption and elimination, while renal elimination is the sole possibility to regulate selenium status. Zinc exerts catalytic, structural, and regulatory functions in more than 300 identified metalloenzymes. Moreover, it is involved in the regulation of gene expression as an integral part of transcription factors.
Selenium is incorporated in selenocysteine and selenoproteins, which are mainly involved in antioxidant defence mechanisms. The recommended value for zinc intake (7–10 mg/d for adults) is generally achieved in the German population, while for selenium (30–70 μg/d for adults), no data from representative nutrition surveys are available. However, deficiency of either trace mineral in healthy adults is unlikely in western countries.
Keywords: iron, zinc, selenium, trace elements, antioxidants, anaemia
Sie finden den Artikel in deutscher Sprache in Ernährungs Umschau 10/10 ab Seite 538.
