OCCURRENCE IN FOODSTUFFS 



32. D. Melnick, M. Hochberg, H. W. Himes and B. L. Oser, ibid., 



1945. 160, I. 



33. T. D. Luckey, G. M. Briggs, C. A. Elvehjem and E. B. Hart. 



Proc. Soc. Exp. Biol. Med., 1945, 58, 340. 



34. E. E. Snell, /. Biol. Chem., 1945, 157, 491 ; J. C. Rabinowitz and 



E. E. Snell, ihid., 1947. 169, 631. 



35. M. Landy and D. M. Dicken, /. Lah. Clin. Med., 1942, 27, 1086. 

 35a. J. C. Rabinowitz, N. I. Mondy and E. E. Snell, /. Biol. Chem., 



1948, 175, 147. 



36. J. L. Stokes, A. Larsen, C. R. Woodward and J. W. Foster, /. Biol. 



Chem., 1943, 150, 17. 



37. G. W. Beadle and E. L. Tatum, Proc. Nat. Acad. Sci., 1941, 27, 



499 ; 1942, 28, 234. 



38. E. C. Barton-Wright, Biochem. J., 1945, 39, x ; Analyst, 1945, 70, 



283. 



39. L. E. Carpenter and F. M. Strong, Arch. Biochem., 1944. 3, 375. 



40. W. A. Winsten and E. Eigen, Proc. Soc. Exp. Biol. Med., 1948, 67, 



513- 



8. OCCURRENCE OF VITAMIN Be IN FOODSTUFFS 



Vitamin Eg occurs in most foodstuffs in the form of complexes.^ 

 In addition to pyridoxine, pyridoxal and pyridoxamine are present in 

 variable proportions.^ This makes the estimation of the vitamin Bg 

 activity of a foodstuff a matter of some difficulty and this fact, coupled 

 with the virtual absence of frank vitamin Bg deficiency in man, prob- 

 ably accounts for the relative lack of information about the occurrence 

 of vitamin Bg in foodstuffs compared with the amount of data avail- 

 able for aneurine or nicotinic acid, for example. 



The method of estimation open to least criticism is the rat growth 

 method, since this estimates the biological activity of a substance 

 directly, without requiring any assumptions to be made concerning 

 the relative vitamin Bg activities of the three compounds. This 

 method was used by Schneider et al.,^ by Henderson et al.,^ by T. W. 

 Conger and C. A. Elvehjem,^ and by Teply et al.^ The first group of 

 workers expressed their results in arbitrary units, making it difficult 

 to relate them to the results obtained by subsequent workers. They 

 showed, however, that cereals and meat contained more vitamin Bg 

 than did fruit and vegetables ; the surprisingly high values reported 

 by them for fats and vegetable oils were probably due to the absence 

 of fat from the basal diet used in their assays. 



Atkin et al.'^ and R. J. WilUams et al.^ used a yeast growth method 

 and J. Bonner and R. Borland ^ and E. C. Barton -Wright 10 the 

 method based on the response of Neurospora sitophila. M. 

 Swaminathan ^^ made use of the colour reaction with diazotised 



315 



