[Zinc: concepts on an essential micronutrient].

It is now well known that zinc is an essential micronutrient. Even though much information is available, there are many points that remain to be studied. zinc is absorbed by the intestine and transported in the plasma by albumin, forming a small exchangeable pool, which is rapidly exhausted even in cases of mild deficiency. zinc is essential for the activity of about 70 enzymes among other functions. Therefore, zinc deficiency produces a great number of clinical disorders, the symptoms of which may range between mild up to serious dysfunctions. These problems are corrected by a dietary supplementation with zinc. The lack of a reliable method to determine the zinc nutritional status reflects the problem to estimate the metal recommended dietary allowances, which are difficulty met specially by children, old persons and pregnant women which constitute the main risk groups. Although our knowledge concerning zinc toxicity is scarce, it is well known that the amounts of zinc that produces toxic effects are much higher than those that are contained in regular diets as well as in diets supplemented with this metal. Therefore, the need of the development of effective strategies, like food fortification with proper zinc compounds, appears as an attractive alternative in order to prevent and/or correct the deficiency of this vital element and to improve the health and the life quality of the whole population.