The effect of dietary iron levels on changes in iron status and zinc-dependent enzyme activities in rats fed two levels of dietary zinc

In order to determine the interrelationship between dietary iron and zinc levels, the effects of dietary iron levels (2, 10, 20, and 40 microg/g) on changes in iron and zinc status and zinc enzyme activities (aminolevulinic acid dehydratase ALA-D EC 4.2.1.24 and alkaline phosphatase ALK-P EC 3.1.3.1) in male Wistar rats were investigated using adequate and marginally deficient zinc diets (25 and 5 microg/g). When rats were fed 5 microg Zn/g diets, body weight gain and food intake remained unchanged at a Fe diet intake of 20 microg/g or greater. Similar tendencies were obtained for hemoglobin, hematocrit, plasma iron, and transferrin saturation. In contrast, liver, spleen, and femur iron concentrations increased gradually with increased iron intake. Feeding diets containing 25 microg Zn/g did not alter these parameters. The percentages of apparent iron absorption in both dietary zinc groups tended to increase with decreasing dietary iron and attained maximum levels at an Fe intake of 10 microg/g. However, In the case of rats fed Fe at concentrations of 2 microg/g Iron absorption decreased. Regardless of the dietary zinc level, rats fed diets with an Fe concentration of 2 microg/g had decreased zinc absorption and plasma ALK-P activity. However, ALA-D activity was not influenced by dietary iron.