Vlll. VITAMIN' A DEFICIENCY IN HUMAN BEINGS Ifil 



associated with hyperkeratosis, xituiniu A blood levels are normal.'^"'®* 

 Intensive vitamin A treatment has been reported as beneficial in mal dc 

 Meleda,^^ postmenopausal vaj^ina cornificalion/" chalazion/' and in pro- 

 gressive deafness and tinnitns.'-"^^ Its reported value in the treatment of 

 acne has not been supported by recent studies J*- ^^ There is also an inter- 

 esting but unconfirmed observation that vernix caseosa is a manifestation 

 of vitamin A deficienc}^, or at least can be reduced by administration of 

 vitamin A to the pregnant mother." Many of the reports mentioned above 

 are cited largely to emphasize trends of interest and application of knowl- 

 edge of vitamin A. Only time and acquisition of many more data can de- 

 termine the validity of the observations and conclusions so far recorded. 



G. HYPERVITAMINOSIS A 



For twenty years or more it has been recognized that animals given a 

 great excess of vitamin A, usually more than 10,000 times their minimal 

 requirement, show evidence of toxic effects. These include anorexia, diar- 

 rhea, disheveled fur, decalcification and spontaneous fractures of bones, 

 scurvy-like hemorrhages, and a variety of lesions in visceral organs. The 

 effects are not related to an excess of vitamin D, or fatty acids or toxic 

 substances present in fish liver oils often used in such studies, for they can 

 be produced by highly potent concentrates of vitamin A or by synthetic 

 vitamin A acetate; moreover, fish liver oils in which vitamin A has been 

 inactivated do not produce these symptoms. Perhaps the most characteris- 

 tic tissue injury, histologically and roentgenographically, is an acceleration 

 of bone remodeling during skeletal maturation to the point where resorption 

 of bone is greater than deposition of new bone; this results in the formation 

 of defective bone which is readily subject to spontaneous fracture. 



It has also been recognized for many years that polar bear liver, an 

 unusually potent source of vitamin A, is shunned by Eskimos and polar 

 explorers because of its toxicity, even when used as a food for Eskimo 

 dogs.'* It is only during the past seven years, however, that a state of 



«8T. Cornbleet, H. Popper, and F. Steigmann, Arch. Dermatol, and Syphilol. 49, 



103 (1944). 

 «9M. J. Brunner and D. L. Fuhrman, Arch. Dermatol, and Syphilol. 61, 820 (1950). 

 TO L. A. Piatt, Am. J. Clin. Pathol. 21, 38 (1951). 

 " C. S. Hickey, Eye, Ear, Nose Throat Monthly 30, 488 (1951). 

 " M. J. Lobel, Eye, Ear, Nose Throat Monthly 28, 213 (1949). 

 " J. R. Anderson, H. J. Zoller, and L. W. .Vlexander, Eye, Ear, Nose Throat }[onthly 



29, 75 (1950). 

 7^ H. W. Bau and L. Savitt, Eye, Ear, Nose Throat Monthly 30, 83 (1951). 

 " F. W. Lynch and C. D. Cook, Arch. Dermatol, and Syphilol. 55, 355 (1947). 

 " G. A. Mitchell and T. Butterworth, Arch. Dermatol, and Syphilol. 64, 428 (1951). 

 " J. V. Straumfjord, Western J. Sury. Obstet. Gynecol. 48, 341 (1940). 

 78 K. Rodahl and T. Moore, Biochem. J. 37, 166 (1943). 



