A precise definition for the essential microminerals (or trace minerals) has not been established. Some define essential microminerals as one that comprises less than one hundredth of one percent of total body weight. Others define it as a nutrient the body needs in concentrations of one part per million or less. These minerals initially gained the nomenclature of trace because their concentrations in tissue were not easily quantified by early analytical method.
Iron appears to be mineral that divides the macrominerals from microminerals; consequently, some define an essential trace mineral as one that is needed by the body in a concentration equal to or lower than iron.
Although fourteen microminerals are designated as essential, questions currently exist about essential of three of trace minerals, i.e., chromium, fluorine and vanadium. Their essentiality is questioned because they fail to meet all the proposed criteria for an essential trace mineral:
- It is present in all healthy tissue of living things.
- Its concentration from one animal to the next is fairly constant.
- Its withdrawal from the body induces reproducibly the same physiological and structural abnormalities, regardless of species studied.
- The abnormalities induced by deficiencies are always accompanied by specific biochemical changes.
- These biochemical changes can be prevented or cured when the deficiency is prevented or cured.
