In analytical chemistry, a trace element is an element in a sample that has an average concentration of less than 100 parts per million atoms, or less than 100 micrograms per gram.
In biochemistry, a trace element is a chemical element that is needed in minute quantities for the proper growth, development, and physiology of the organism. In biochemistry, a trace element is also referred to as a micronutrient.
In geochemistry, a trace element is a chemical element whose concentration is less than 1000 ppm or 0.1% of a rock's composition.
The term is used mainly in igneous petrology.
Trace Elements involved in human Nutrition :
Our diets, consisting of more and more refined foods are causing concern that modern man is not receiving enough of these trace elements in his food sources, and dietary supplements may be of use in combating this shortage.
The interaction of these micro-nutrients are difficult to study, since they are found occurring together in various forms and amounts in the diet, and their absorption from the intestinal tract may be dependent on their relative concentrations, and might be synergetic or antagonistic, and the amount could depend on the amount of other essential trace elements in the diet.
Essential nutritional elements
To decide whether a micronutrient is “essential” or not, a wide variety of criteria is used, such as the presence of the nutrient in healthy tissue, if it appears in the fetus and newborns and if the body maintains homeostatic control over its uptake in the bloodstream or tissue and its excretion.
The following are considered essential micronutrients: cobalt, copper, chromium, fluorine, iron, iodine, manganese, molybdenum, selenium and zinc.
On the other hand, nickel, tin, vanadium, silicon, boron have recently been found as important micronutrients, whereas aluminum, arsenic, barium, bismuth, bromine, cadmium, germanium, gold, lead, lithium, mercury, rubidium, silver, strontium, titanium and zirconium is all found in plant and animal tissue, yet their importance is still being determined.
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