Effect of Zinc and Iron Fortification of the Feed on Liver and Thyroid Function in Rats

Changes in plasma glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT), triiodothyronine (T3), and thyroxin (T4) of male rats, following 8 weeks of administration of different concentrations of elemental iron (EI), sodium iron ethylenediaminetetraacetate (NaFeEDTA), zinc sulfate (ZnSO4), and zinc oxide (ZnO) in whole wheat flour were investigated. Liver enzymes and thyroid hormones were determined using colorimetric methods and enzyme immune assay, respectively. Ingestion of fortified diets by the male rats did not show a marked effect on GOT and GPT, the exception being NaFeEDTA fed alone and EI with ZnO-fortified diets indicating a significant (p < 0.05) decrease in GOT levels in rats. Similarly, only NaFeEDTA significantly (p < 0.05) increased thyroxin, while EI, ZnSO4, and ZnO either alone or in any combination did not alter thyroid secretions. Changes in GOT, GPT, T3, and T4 levels, as a result of ingesting iron and zinc-fortified diets by rats, ranged in the safe limits.