It is known that vitamin A is a physiologic prophylactic against infection by virtue of the fact that it guards the barrier of integrity of the epithelial linings of the mucous membranes and the skin. The high incidence of infection in experimental animals deficient in vitamin A is the usual and early observation of all research workers.1 Accumulating experimental evidence tends to support the hypothesis that vitamin A also plays a part as an anti-infectious agent. Bloch,2 noting many severe infections in his original studies on vitamin A deficiency in infants, maintained that vitamin A is of special importance to the organism for resisting and overcoming infection.
The histologic changes in cases of A avitaminosis have been studied by several investigators. Wolbach and Howe3 concluded that the outstanding change is a substitution of stratified keratinizing epithelium for normal epithelium in various parts of the respiratory tract, eyes