All life on earth as we know it today has evolved in the presence of natural levels of zinc. Due to its general availability to organisms (bioavailability) and its characteristics, zinc has been used by nature to play a specific role in various biological reactions. As such, zinc is an essential element for all life, from man to the smallest micro-organism.

Organisms take up the essential elements they need from their environment which 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 a concentration range for each essential element within which its requirements are satisfied. Thus, an Optimal Concentration Range for zinc exists for each living organism, including man. Indeed, there is an Optimal Concentration Range for Essential Elements (OCEE) for each essential element and each living organism.

Zinc plays an essential role in human metabolism. For example, zinc is vital for the proper functioning of more than 200 enzymes, for the stabilization of DNA and the expression of genes, and for the transfer of nervous signals. The human body contains 2-3 gram of zinc (compared with 7 gram of iron) which is found everywhere in the body, with the highest levels in muscles, liver, kidneys, bones and prostate. The recommended daily zinc intake is 12 mg/day for adult women and 15 mg/day for adult men. Daily intake is not only dependent on food, but also on sex, age and general health status. Growing infants, children, adolescents, women in pregnancy and the elderly have a higher zinc requirement. Certain groups are known to have an increased demand for zinc and have a higher risk of not getting enough zinc. Food is the primary source of zinc for man, with only a small part coming from drinking water. Food products differ in their zinc content. The major sources of zinc in the diet are redmeat, poultry, fish, seafood, whole cereals and dairy products.

Population groups with increased demand for zinc
Children and adolescents: Higher demand due to growth
Pregnant and lactating women: Higher resorption by the fetus and in the milk
Elderly people: Reduced body functions, unbalanced diet
People doing hard physical work: Increased general demand
Diabetics and alcoholics: Higher excretion
Smokers: Reduced absorption
Patients with large wounds: Extreme losses and higher demands