Supplemental levels of iron and calcium interfere with repletion of zinc status in zinc-deficient animals.

Negative interactions between minerals interfering with each other’s absorption are of concern when iron
and calcium supplements are given to pregnant women and children. We have previously reported that
supplemental levels of iron and calcium inhibit the bioaccessibility of zinc, and compromise zinc status in
rats fed diets with high levels of these two minerals. The present study examined the effect of supplemental
levels of iron and calcium on the recovery of zinc status during a zinc repletion period in rats rendered
zinc-deficient. Iron and calcium, both individually and in combination, significantly interfered with the
recovery of zinc status in zinc deficient rats during repletion with normal levels of zinc in the diet. Rats
maintained on diets containing supplemental levels of these two minerals had significantly lower body
weight, and the concentration of zinc in serum and organs was significantly lower than in zinc-deficient
rats not receiving the supplements. Iron and calcium supplementation also significantly inhibited the
activity of zinc-containing enzymes in the serum as well as liver. Both iron and calcium independently
exerted this negative effect on zinc status, while their combination seemed to have a more prominent
effect, especially on the activities of zinc containing enzymes. This investigation is probably the first
systematic study on the effect of these two minerals on the zinc status of zinc deficient animals and their
recovery during repletion with normal amounts of zinc.