Influence of Different Forms of Vitamin A,Thyroxine,and Thiouracil on Carotenoid Utilization by Chicks ∗

Abstract

Summary

Forms of vitamin A having alcoholic, aldehydic, or acidic terminal functional groups, when fed at 100,000 IU of vitamin A/kg of diet, depressed carotenoid utilization. The retinoic acid caused the decrease in the carotenoid content of serum, liver, and skin to a greater extent than other forms of vitamin A. In an experiment designed to study the effect of vitamin A in combination with thyroxine or thiouracil on the utilization of carotenoids, a similarity of their effects between high vitamin A and thiouracil was evident.