My colleague Pam Schoenfeld, MS, recently put me onto an eye-opening article on vitamin A. Titled "Tissue Changes Following Deprivation of Fat-Soluble A Vitamin"1 by S. Burt Wolbach, MD and Percy R. Howe, MD, the article was published in the Journal of Experimental Medicine in 1925. This paper is interesting for several reasons.

Primary Effects of Vitamin A Deprivation

The first concerns the changes these researchers observed when they deprived rats of vitamin A. The main effect was keratinization of the epithelial tissues.

The epithelial tissues are thin tissues that cover all the exposed surfaces of the body, such as the skin, the inner lining of the mouth, the digestive tract, secretory glands, the lining of hollow parts of every organ such as the heart, lungs, eyes, ears, the urogenital tract, as well as the ventricular system of the brain and central canals of the spinal cord.