472 THIAMINE 



XII. Requirements and Factors Influencing Them 



A. OF ANIMALS 

 B. C. P. JANSEN 



The animal body is unable to store thiamine to any large extent. An 

 adult human body does not contain more than about 30 mg. of thiamine. 

 As the body continually loses thiamine in the urine, feces, and perspira- 

 tion, it needs a constant supply. 



It is difficult to find an exact criterion for measuring the requirement of 

 an animal. The growth curve of young animals is most frequently used as 

 a criterion. However, a drawback is that the curve indicating the influence 

 of the thiamine content of the diet on the growth of the animal is an asymp- 

 totic one. Thus it is difficult to fix the maximum (or "normal") growth. 

 Other methods used are the influence of the diet on the thiamine content 

 of the blood or on normal or abnormal metabolism, i.e., on the pyruvic acid 

 content of the blood. 



As a thiamine deficiency produces anorexia, CowgilP used the "normal 

 appetite" as a criterion. 



Furthermore it is assumed that a certain (minimum) amount of thiamine 

 is essential to keep an animal alive, to promote normal growth, and to 

 protect it from polyneuritis. On the other hand, the work of Rasmussen 

 et al? and of Foster et al.^ clearly demonstrated that mice are more resistant 

 — or, as Schneider* puts it, less susceptible — to a certain strain of polio- 

 myelitis virus if the thiamine content of the diet is reduced to an amount 

 below the content that is required in other respects. Therefore it seems that 

 a diet which may be considered thiamine deficient gives these animals 

 better protection against poliomyelitis. 



It is obvious that a great many factors exert influence on the requirement 

 of thiamine in animals. The factors studied in the greatest detail are: 



1. Size of the animal. 



2. Composition of the diet. 



3. Physical state of the animal (hyperthyroidism, pregnancy, lactation, 

 fever, age, etc.). 



4. Climate (temperature). 



5. Intestinal microflora. 



6. Individual genetic factors. 



7. Performance of muscular work. 



1 G. R. Cowgill, The Vitamin B Requirement of Man. Yale University Press. New 

 Haven, 1934. 



2 A. F. Rasmussen, H. A. Waisman, C. A. Elvehjcm, and P. F. Clark, ,/. Infectious 

 Diseases 74, 41 (1944). 



3 C. Foster, J. H. Jones, W. Ilcnlc, and F. Dorfman, J. expil. Med. 80, 257 (1944). 

 * H. A. Schneider, Vitamins and Hormones 4, 35 (1946). 



