The essentiality of zinc was first demonstrated in rats by feeding a diet that was chemically deficient in zinc.1The zinc required to meet the needs of these rats was so little that for many years it was assumed that a deficiency of zinc was unlikely to occur. Therefore, the practical aspects and prevalence of zinc deficiency world- wide was not appreciated until 1960 when it was determined that phytate, inositol hexaphosphate (Figure 1), a natural constituent of all plant seeds, was an important aspect in the production of zinc deficiency. This was first demonstrated using baby chicks as the experimental animal model (Table 1).2 it was later demonstrated in pigs3 (Table 2)and rats4 (Figure 2). This evidence included not only growth retardation but also parakeratosis, a severe symptom of zinc deficiency seldom seen in human subjects. Thus, studying the effects of zinc – deficiency with chemically deficient diets becomes an academic curiosity, but to study zinc deficiency utilizing phytate containing diets becomes a serious practical problem.
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