Zinc absorption and excretion in adult rats at zinc deficiency induced by dietary phytate additions: I. Quantitative zinc metabolism of 65 Zn‐labelled adult rats at zinc deficiency

  Model studies on zinc (Zn) deficiency are usually performed with growing individuals (e.g. rats). Under such conditions, severe symptoms of Zn deficiency can be induced within a few days by feeding purified diets poor in Zn. The major reason for the quick experimental response is the high dietary Zn requirement for growth. However, the results retrieved from model studies with growing animals may be coupled with the intensive anabolic situation of the organism and they may therefore not fully represent the metabolism of adult individuals living close to the maintenance level, like most humans for example. On the other hand, in adult individuals it may take a long time to induce an experimental Zn deficiency of sufficient severity solely on the basis of purifed diets. One reason is the substantial drop in Zn requirements when growing individuals approach their final body weight and become adult (R oth and K irchgessner 1980; W indisch and K irchgessner 1994a). Another reason is the fact that purified diets do not usually contain relevant amounts of complexing agents such as phytate, which would increase the dietary requirement of Zn (D avis and N ightingale 1975; M orris and E llis 1980, 1989; F orbes et al. 1984). It was therefore the aim of the present experiment to add a purified phytate formulation to semisynthetic diets and to study their potential to induce Zn deficiency of controlled severity in adult rats as a model to individuals living at the metabolic level of maintenance.