Trace Mineral Deficiencies

Authored by: Forrest H. Nielsen

Handbook of Nutrition and Food

Print publication date:  July  2013
Online publication date:  April  2016

Print ISBN: 9781466505711
eBook ISBN: 9781466505728
Adobe ISBN:

10.1201/b15294-16

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Abstract

By 1940, the concept of essential nutrients was well established. They were defined as chemical substances found in food that could not be synthesized by the body to perform functions necessary for life. In the 1960s and 1970s, the standard for essentiality was liberalized for mineral elements because it was hypothesized that diets could not be made low enough in some elements to cause death or interrupt the life cycle (interfere with growth, development, or maturation such that procreation is prevented). Thus, during this time period, an accepted definition of an essential mineral element was one whose dietary deficiency consistently and adversely changed a biological function from optimal, and this change was preventable or reversible by physiological or nutritional amounts of the element. This definition of essentiality became less acceptable when numerous elements were suggested to be essential based on small physiological or biochemical differences in experimental models fed low and supplemental (some possibly supra nutritional) amounts of the elements. These differences were regularly questioned to be indicative of a suboptimal function and alternatively suggested to be the consequence of a pharmacologic action, a toxic response, or an effect on intestinal organisms. This resulted in the present conviction that a mineral element cannot be considered essential unless it has a defined biochemical function if its lack cannot be shown to cause death or interrupt the life cycle. However, some elements (e.g., chromium) that do not meet the current definition of essentiality are occasionally still indicated as essential in current literature because they were ingrained as so by using the older definition of essentiality in the 1960s and 1970s. Some mineral elements have defined biochemical functions in lower species (e.g., nickel) or have been found to interrupt the life cycle in only a limited number of vertebrates (e.g., boron) and thus are occasionally designated as essential. Some elements (e.g., vanadium) have beneficial actions when supplemented in supra nutritional amounts. These findings suggest that some mineral elements other than those firmly established as essential might be of nutritional importance. Thus, changes in both higher animals and humans consuming low and apparently nutritional amounts (amounts normally found in food) of these elements will be described here.

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