Zinc - Essential for Man and the Environment
Zinc is essential for all life. It plays a specific role in various biological reactions of all living organisms - humans, animals, plants and the smallest microorganisms.
Organisms take up the essential elements they need from their environment, that means directly from air, water, soil, and from food. When their cellular requirements for these elements are satisfied, growth and development are optimal. When uptake is too low, deficiency occurs and adverse effects can be observed. On the other side, uptake of too much of an essential element can lead to toxicity. Between these two extremes, each organism has an optimal concentration range for each essential element within which it can regulate its internal zinc level so that its metabolic requirements are satisfied.
(Van Assche et al.1996)
The amount of zinc available varies significantly geographically and seasonally and zinc deficiency is a widespread problem. It is estimated that zinc deficiency affects one third of the worlds population. In the World Health Report 2002 WHO says that zinc deficiency is one of the leading causes of illness and disease in low-income countries. It ranks 5th among the leading 10 risk factors. Even on a global scale zinc deficiency ranks 11th out of the 20 leading risk factors. WHO attributes 800,000 deaths worldwide each year to zinc deficiency and over 28 million healthy life years lost. Zinc deficiency is responsible for approximately 16% of lower respiratory tract infections, 18% of malaria and 10% of diarrhoeal disease. WHO points out that zinc deficiency is largely related to inadequate intake or absorption of zinc from the diet and zinc supplementation and fortification both prove to be very cost-effective interventions in all regions of the world.
Zinc deficiency in agricultural soils and crops is also a common phenomenon and constitutes a major problem in many parts of the world as crop yields are reduced and the quality of crops is often impaired. Relatively small amounts of zinc compounds can cure deficiency and last for several years before they need to be repeated.
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