Trace Elements in Health and Diseases

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Popular conception lead people to take nutrients for well-being through food. They, even of ancient times, could know by personal experience the linkage of good food to performance. Hence, meat, milk and other good foods, which have been known to be of excellent nutritive value, were sought after. Later, during contemporary period there had been specific craze for proteins from food and then vitamins. This desire has now been enlarged for metals so much that people tend to take tablets of vitamins and minerals, with or without medical prescription.

Some metals like calcium, phosphorus and iron are necessary in larger amounts, as a RDA (recommended daily dietary allowance) chart will show and some in around trace concentrations. The latter group is very interesting: essential but in low concentrations and toxic in more than desirable or tolerable concentrations. The excess amounts generally cannot be flushed out in many cases by the kidneys even if the salts are water soluble unlike the water soluble vitamins. These accumulate like the fat soluble vitamins and are similarly toxic. It is as if the excess having no remaining work to perform interferes with the work of others specially of metals of s of similar properties and hence of the same valency.

Essentiality of many of the metals was not apparent effortlessly. Small amounts of the requirements could be met easily through food even without being aware of the facts. Vegetation extracts metals from soils and to some extent from water.

The science of human nutrition is mainly concerned with defining the optimum amounts of the constituents of food necessary to achieve or maintain health throughout the full span of life in all groups of the population. Thus, the pregnant woman, the new-born, the growing child, the adult and the old person-all have specific dietary requirements for their different physiological states. A faulty diet in which the amounts of nutrients are inadequate or in the wrong proportions lead eventually to disease or may contribute to the development of disease. Nutrition therefore plays a part in both preventive and curative medicine, and the effectiveness of its role depends upon continued investigations into the metabolism of nutrients.

Development in knowledge has indicated that the idea of nutrition may not be restricted to protein, carbohydrate, lipid and vitamins but also to minerals, particularly to those required in trace amounts. Trace elements may be categorised as follows (i) those for which humans have a well-defined need, such as iron, iodine and zinc, (ii) those for which estimated, safe and adequate daily dietary intakes have been established such as copper, manganese, fluoride, chromium, selenium and molybdenum, (iii) those that are important to certain animals but for which human requirements have not been well defined such as nickel, silicon and (iv) those that have some toxic effects on the body such as aluminium, arsenic, and yet show well defined functions.

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