476 VITAMIN Bi2 



rations the L. leickmannii 313 assay method would indeed be a most 

 sensitive and practical method for vitamin B)2 determination. 



IX. Occurrence in Food 



THOMAS H. JUKES and WILLIAM L. WILLIAMS 



Early studies on the distribution of the anti-pernicious anemia factor 

 (APF) in food are difficult or impossible to interpret because a response in 

 pernicious anemia may be obtained to either folic acid or vitamin B12. In 

 fact, folic acid is more readily utilized than vitamin B12 by the oral route 

 in this disease. Therefore, one wonders A\'hether the responses first obtained 

 by Minot and Murphy to the ingestion of large quantities of beef liver 

 may have been due to the folic acid content of this food rather than to the 

 presence of vitamin Bi2.^ Anti-anemic effects were reported by various 

 investigators for extracts prepared from kidney,^ brain, salivary glands, 

 saliva,^ pancreas, and spinach.* 



The "extrinsic factor," which now appears to be vitamin B12, was meas- 

 ured by its effect in producing a response in pernicious anemia when fed 

 together Avith gastric juice. However, folic acid present in such foods could 

 also produce a response whether or not gastric juice was added, and it 

 seems reasonable to conclude that the so-called extrinsic factor activity of 

 yeast must have been due in large part to its content of folic acid. Other 

 sources of the extrinsic factor include lean meat, milk, and crude casein, 

 and the activity of these sources was probably due to their vitamin B12 

 content, since they are low in folic acid. 



The distribution of APF as measured by the growth response of chicks 

 on an all-vegetable diet led to the compilation of information which was 

 later shown to be related to the presence of Aitamin B12. In this manner 

 fish meal, fish solubles, meat scrap, milk, liver, cow manure, the dried 

 rumen contents obtained from cattle, and fermented chicken manure were 

 shown to be sources of vitamin B12. Alaska herring meal appeared to be a 

 better source than certain other types of fish meal. 



Studies by Gary and Hartman^ with factor X led to the following con- 

 clusions as a result of assays with young rats on a basal diet deficient in 

 vitamin B12: 



' G. R. Minot and W. P. Murphy, /. Am. Med. Assoc. 87, 470 (1926). 



2 W. S. McCann, Proc. Soc. Exptl. Biol. Med. 25, 255 (1928). 



3 W. Hofer and L. Hofer, Klin. Wochschr. 13, 6101 (1934). 



* S. Okadas, M. Shamato, and F. Yanasef, Nagoi/o J. Med. Sci. 11, 147 (1937). 

 » C. A. Gary and A. M. Hartman, Yearbook Agr. 1943-1947, U. S. Dept. Agr. p. 783. 



