Trace Mineral Elements, Mammalian Requirements and Man’s Presumptive Needs

Abstract

Trace mineral elements are present in all links of the food chain (Underwood, 1977). In plants, animals, and man, the essential elements function as catalysts, required in small amounts for optimal growth, productivity and health. Most are difficult to measure and the interpretation of measured values is complicated by the incomplete understanding of principles that govern their biological availability and interactions. Thus, it is not surprising that the initial scientific efforts to define nutrient requirements of plants, animals, and man were directed toward the macronutrients and that man’s modern successes in agricultural production were based on the application of knowledge of macronutrient requirements. The enormous benefit derived from the use of chemical fertilisers is but one example. When the needs for macroelements are met, the supply of microelements may become limiting (Bertrand, 1912). The rate of depletion of agricultural soils of essential micromineral elements can be calculated; it varies from one soil type to another, and depends on agricultural practices, but depletion of the microelements can ultimately result in a reduction of either crop yield or the microelement concentration in the plants or both. This, in turn, will affect the farm animals living on these lands, possibly diminishing growth rates and productivity (Underwood, 1977). Microelement deficiency can also, albeit less directly, affect human health by contributing to low, perhaps even deficient, intakes in the affected regions.