The purpose of this study in rats was to determine if the absorption and accumulation of zinc, cadmium and iron differ amoung diets based on different grains and, if so, what differences among the grains might account for the differences in mineral absorption.

Publisher Summary
Although there are numerous qualitative studies in domestic animals, there are few quantitative bioavailability data for mammalian species. In view of early observations that the zinc in oilseed meals is of low availability, several investigators have performed in vitro zinc binding assays to serve as indicators of zinc bioavailability. Smith and colleagues have developed an in situ vascular perfusion system to study zinc absorption by the rat intestine. The first attempt to evaluate zinc bioavailability was quantitatively used in growing chicks and rats fed purified diets supplemented with graded levels of ZnCO3 as a reference. Although the zinc concentration in most soft tissues varies little with zinc status, plasma and bone zinc are low in animals deprived of zinc. Several of zinc metalloenzymes have been identified in nature, but most of the metalloenzymes bind zinc so tightly that their activities do not change during nutritional deprivation. Zinc balance has been used widely in human studies, but few animal balance trials have been reported. Two major dietary factors that affect zinc bioavailability are (1) chelating agents and (2) metal ion interactions. Fiber has been reported to decrease zinc bioavailability in man, but experiments with rodents have shown little or no effect. Standard sources of zinc used in bioavailability assays have included the sulfate, carbonate, chloride, oxide, and acetate forms of the element, with zinc sulfate having been used most frequently.

The Availability of Zinc, Cadmium and Iron from Different Grains Measured as Isotope Absorption and Mineral Accumulation in Rats

Citations

17 – Zinc bioavailability

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