HUMAN AND ANIMAL REQUIREMENTS 



Monkeys 



In order to prevent vitamin M deficiency in monkeys, loo /xg. per 

 day of liver vitamin Be or of synthetic L. casei factor or 200 to 300 /xg. 

 per day of yeast vitamin Be conjugate were required.^ 



Humans 



No direct information is yet available as to the amount of folic 

 acid that must be ingested in the diet in order to maintain a normal 

 individual in full health, but an estimate of the probable folic acid 

 requirements of humans can be made from a consideration of the 

 amounts that have to be given to maintain a normal blood picture in 

 patients with pernicious or other types of anaemia. Such estimates 

 have been made by L. S. P. Davidson and R. H. Girdwood,* who 

 stated that the daily requirement of folic acid was 0-5 to i m.g., 

 although the recommended dose for the initial treatment of pernicious 

 anaemia is higher — 5 to 10 mg. daily by mouth. 



For the initial maintenance therapy of nutritional megaloblastic 

 anaemia, pernicious anaemia of pregnancy, idiopathic refractory 

 megaloblastic anaemia or the sprue syndrome, 5 to 10 mg. of folic 

 acid per day are advocated. In the first two diseases, treatment can 

 be stopped when the blood count is normal, but in idiopathic refractory 

 megaloblastic anaemias treatment for life is necessary at a suggested 

 dose level of 5 mg. daily. The maintenance treatment in sprue will 

 vary according to the response, and folic acid may have to be supple- 

 mented by oral liver extract or proteolysed liver. From these data, 

 therefore, the probable human requirement of folic acid is up to 5 mg. 

 per day. 



Rats 



To cure all the symptoms of folic acid deficiency in rats, 5 fxg. of 

 pteroylglutamic acid were said to be required per day,^ whereas to 

 cure the granulocytopenia only 5-7 /xg. were required per week.® 

 Larger amounts were needed during pregnancy and, particularly, 

 during lactation.*^ 



References to Section 13 



1. D. V. Frost, F. P. Dann and F. C. Mclntire, Proc. Soc. Exp. Biol. 



Med., 1946, 61, 65. 



2. E, J. Robertson, L. J. Daniel, F. A. Fanner, L. C. Norris and G. F. 



Heuser, ibid., 1946, 62, 97. 

 2a. B. S. Schweigert, H. L. German, P. B. Pearson and R. M. Sherwood, 

 /. Nutrition, 1948, 35, 89 ; W. W. Cravens and J. G. Halpin, 

 ibid., 1949, 37, 127. 



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