Comparison between time-dependent changes in iron metabolism of rats as induced by marginal deficiency of either vitamin A or iron.

To compare the changes in Fe metabolism during the development of vitamin A and Fe deficiencies, rats were given either a control diet with sufficient Fe (35 mg added Fe/kg feed) and retinol (1200 retinol equivalents/kg feed), a diet without added vitamin A or a diet with sufficient vitamin A but only 3.5 mg added Fe/kg feed. During a period of 10 weeks, indicators of vitamin A and Fe status were monitored. Neither vitamin A nor Fe deficiency produced clinical signs. Fe deficiency induced an immediate fall in blood haemoglobin concentration. Vitamin A deficiency produced a mild anaemia as the first change in Fe metabolism, pointing to impaired erythropoiesis. This effect was followed by a rise in Fe absorption and an increased amount of Fe in the spleen. By the end of the study, blood haemoglobin, packed cell volume, plasma Fe and Fe content in kidney and femur had increased above control levels, while total Fe-binding capacity had decreased. We speculate that the initial anaemia was masked later by haemoconcentration. The decrease in Fe mobilization, shown by lower total Fe-binding capacity, and the increase in Fe absorption may have caused the observed continuous rise in tissue Fe concentration in rats with vitamin A deficiency. In the rats with Fe deficiency, low tissue Fe levels coincided with high Fe absorption and high total Fe-binding capacity. Thus, changes in Fe metabolism with vitamin A deficiency differed from those with Fe deficiency.