CHOLINE 



sweat was only 07 to 1-5 % of the intake (624 to 899 mg.) and most 

 of this was recovered from the urine. ^ A change in the temperature 

 and relative humidity did not affect the total amount excreted, but 

 more appeared in the sweat. 



The concentration of choline in the plasma was reduced in depan- 

 creatised dogs maintained on insulin, and the fall was associated with 

 the development of fatty livers.^ The fall in the plasma choline 

 could be prevented by a fraction prepared from pancreas, and this also 

 prevented fatty formation in depancreatised dogs ; it did not contain 

 choline. The average choline content of human serum was lowest in 

 July ; five times as much was present in February and March.* 



References to Section 8 



1. R. W. Luecke and P. B. Pearson, /. Biol. Chem., 1945, 158, 561. 



2. B. C. Johnson, T. S. Hamilton and H. H. Mitchell, ibid., 1945, 169, 5. 



3. I. L. Chaikoff, C. Entenman and M. L. Montgomery, ibid., 1945, 



160, 387. 



4. J. A. Schlegel, Proc. Soc. Exp. Biol. Med., 1949, 70, 695. 



9. HU2V1AN AND ANIMAL REQUIREMENTS OF CHOLINE 



Estimates of the amount of choline chloride required by rats vary 

 considerably. Thus, 10 to 20 mg.,i 4 to 6 mg.,2 10 mg.,^ 3 mg.* 

 and 12 to 15 mg.^ per day are the amounts stated by different groups 

 of workers to be necessary to prevent fatty liver formation. Another 

 group of workers claimed that as much as 20 mg. per day were required 

 to prevent rustiness in albino rats,^ whilst Wistar (albino) rats were 

 said to require only 4 to 6 mg. daily compared with 10 mg. daily found 

 to be necessary to prevent fatty liver formation in hooded rats of the 

 Wisconsin strain. "^ An average value for the choline requirement of 

 rats could therefore be about 100 mg. per day per kg. of bodyweight. 

 The amount of choline required increased with the temperature at 

 which animals were kept, from 075 g. per kg. of diet at 68° F. to 5 g. 

 per kg. at 90° F.^ 



According to one group of workers ^ dogs required 50 to 100 mg. 

 of choline chloride per 100 g. of ration, or 25 to 100 mg. per kg. of 

 bodyweight per day, whilst C. Entenman and I. L. Chaikoff ^^ found 

 the daily requirement to be about 35 mg. per kg. of bodyweight. 



According to O. D. Abbott and C. U. de Masters,!^ chicks required 

 about 75 mg. per kg. of bodj^weight. 



Willstaedt et al}"^ estimated the human requirement of choline by 

 assaying the amounts present in a normal diet and found that the 

 daily intake varied from 502 to 1047 mg. per day with an average 

 value of 646 mg. According to this calculation, therefore, humans 



594 



