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Submitted to: Book Chapter
Publication Type: Book / Chapter Publication Acceptance Date: 3/23/2002 Publication Date: 10/1/2003 Citation: Nielsen, F.H. 2003. Trace elements. Book Chapter. In: Katz, S.H., Weaver, W.W., editors. Encyclopedia of Food and Culture. New York, NY: Charles Scribner's Sons. p. 410-415. Interpretive Summary: Trace elements are defined as mineral elements that occur in living systems in micrograms per gram of body weight or less. Trace elements of greatest practical concern in human health are iodine, iron and zinc. Suggestive evidence is emerging that cobalt (as vitamin B12), copper, selenium, boron and chromium should be considered as elements that have practical nutritional significance in assuring or promoting health and well-being. These trace elements have several key physiologic roles. Specific elements are essential components of some enzymes; donate or accept electrons necessary for reactions generating and utilizing metabolic energy; bind, transport and release oxygen; impart structural stability to important biological molecules; and control important biological processes through such actions as facilitating the binding of molecules to receptor sites on cell membranes, altering the structure or ionic nature of membranes to prevent or allow specific molecules to enter or leave a cell, and inducing gene expression resulting in the formation of proteins involved in life processes. The eight trace elements named were judged as being of greatest significance in food and culture so a general overview of their roles in normal physiology, regulatory processes that govern their uptake and excretion, and the consequences of their deficient and excessive intakes is presented. In addition, their recommended intakes and foods that provide those intakes are presented. The review indicates that the determination of the importance of trace elements for human health and well-being is a work in progress with some exciting advances likely in the future. Technical Abstract: Trace elements are defined as mineral elements that occur in living systems in micrograms per gram of body weight or less. Trace elements of greatest practical concern in human health are iodine, iron and zinc. Suggestive evidence is emerging that cobalt (as vitamin B12), copper, selenium, boron and chromium should be considered as elements that have practical nutritional significance in assuring or promoting health and well-being. These trace elements have several key physiologic roles. Specific elements are essential components of some enzymes; donate or accept electrons necessary for reactions generating and utilizing metabolic energy; bind, transport and release oxygen; impart structural stability to important biological molecules; and control important biological processes through such actions as facilitating the binding of molecules to receptor sites on cell membranes, altering the structure or ionic nature of membranes to prevent or allow specific molecules to enter or leave a cell, and inducing gene expression resulting in the formation of proteins involved in life processes. The eight trace elements named were judged as being of greatest significance in food and culture so a general overview of their roles in normal physiology, regulatory processes that govern their uptake and excretion, and the consequences of their deficient and excessive intakes is presented. In addition, their recommended intakes and foods that provide those intakes are presented. The review indicates that the determination of the importance of trace elements for human health and well-being is a work in progress with some exciting advances likely in the future. |
