Metabolic interrelationships in the utilization of trace elements

Abstract

The behaviour of the trace elements in biological systems is mostly a reflection of the strong affinity of cellular components for these elements. This behaviour can be modified by changes in the environment of the cell which influence the supply of a particular element available to participate in cellular reactions, by changes which modify cellular components in such a manner that their affinity for the element is increased or decreased, or by changes in the intra-or extra-cellular concentration of elements which compete for a specific binding site. Although in this review we are concerned with nutritional changes that may modify trace-element metabolism in the intact animal we are, in effect, dealing with these reactions. With this in mind I have selected examples of recent advances in knowledge of the influence of the nature of the diet on processes such as the liberation of trace elements from food material, the storage of these elements in the tissues, their incorporation into their functional units in the cell and finally their excretion.

Occurrence of chlorophyll in dried bract of cotton plant

“…This waste material contains bract, and bract has been shown to contain chlorophyll, which can be readily converted to pheophytin. It has been suggested that pheophytin may bind Cu, making it unavailable for utilization by cattle, etc., and therefore accounting for the observations that the Cu status of cattle falls during the summer grazing period and improves during winter, even in diets that contain less Cu (Mills, 1964). Copper pheophytin has been shown to be readily formed (Mills, 1964) after treatment of aqueous acid suspensions of grass with ionic Cu.…”

“…It has been suggested that pheophytin may bind Cu, making it unavailable for utilization by cattle, etc., and therefore accounting for the observations that the Cu status of cattle falls during the summer grazing period and improves during winter, even in diets that contain less Cu (Mills, 1964). Copper pheophytin has been shown to be readily formed (Mills, 1964) after treatment of aqueous acid suspensions of grass with ionic Cu. The isolated product is stable even in the presence of sulfide and chelating agents and decomposes appreciably to ionic Cu only below pH 3.2.…”

Mineral Balance in Young Men Fed a Fortified Milk-Base Formula

“…Apparently, the absence of phytic acid and the liberal amount of protein in this diet may have spared losses of zinc, magnesium and certain other elements via the stool [19,20].…”

Chronic copper toxicity of ruminants

“…The effect of protein concentration on liver copper may, therefore, be confounded with other factors in the protein source. Mills (1964) has reviewed the influence of the type of dietary protein on trace element metabolism and, although the protein content of the ration per se may have an effect on copper metabolism, the parts played by other known interfering factors, such as molybdenum and sulphate, will have to be taken into account before a final assessment can be made.…”