416 



THE BIOCHEMISTRY OF B VITAMINS 



Thymine, folic acid, and vitamin B 12 are all effective in bringing about 

 a remission of the symptoms of pernicious anemia, but the relative effec- 

 tive doses of these substances varies a millionfold. From 5 to 10 grams 

 of thymine daily, or approximately 10-mg daily of folic acid are required, 

 while an initial intramuscular injection of 15 fig of vitamin B i2 is effective 

 for a number of days. Spies et aL 124 have compared the effects of these 

 three substances in a case of pernicious anemia that was admitted to the 

 hospital for treatment three successive times. Their graphs are reproduced 



•2 20 



10 - 



I. 



THYMINt 



^ 



1 1 1 1 1 1 1 1 1 1 1 1 1 1 



^ 



.!...■«.« 



FOLIC AdO 



. i ........... i 



VTTAMW ft a 



ii i ii 1 1 1 n 1 1 1 



......... .^ »■ i 



Figure 18. Hematological response in a case of pernicious anemia. 



in Figure 18 and are of particular value because of the analogous data 

 obtained from cases of tropical sprue and nutritional macrocytic anemia 

 shown in Figures 19 and 20. 



The evidence now available suggests that pteroyl heptaglutamate is 

 not appreciably active in pernicious anemia, 125 - 126 and that none of the 

 folic acid vitamins are effective in curing all the symptoms. Indeed, 

 neither folic acid nor thymine prevents the development of subacute 

 combined degeneration of the spinal cord, nor do they retard it once it 

 is initiated. 127 Folic acid in some cases seems to aggravate the neurologi- 

 cal symptoms, although this effect may possibly be due to impurities in 



