B VITAMIN DEFICIENCY STATES 397 



extent to which such subclinical deficiencies occur is at present unknown, 

 but a growing body of evidence seems to suggest that even in populations 

 having a high standard of living there may be a high incidence. 17 The 

 early rapid commercial overexploitation of vitamins which resulted in a 

 universal "vitamin consciousness" has now been followed by a reactionary 

 era of public resistance to the general topic of vitamins, with the result 

 that progress in the study and treatment of subclinical deficiencies may 

 well be extremely difficult for some years. 



An extended discussion of B vitamin deficiencies has not been under- 

 taken in this volume for a number of reasons. Primarily this monograph 

 is concerned with the more biochemical aspects of B vitamins, and a very 

 extensive discussion of clinical material would be out of place. The clini- 

 cal picture, moreover, is more appropriately one for clinicians and pathol- 

 ogists, and is not within the scope of interest of either the authors or most 

 of the readers of this book. The references found in this section, therefore, 

 are generally the recent publications which add something to the long 

 known overall picture of deficiency. Finally, a great number of excellent 

 clinical treatises exist, which may be turned to by those whose interests in 

 this aspect go beyond the coverage given here. In keeping with the pur- 

 poses set forth in the preface, therefore, this chapter presents a broad gen- 

 eral survey of the essential facts concerning the B avitaminoses, omitting 

 a voluminous mass of supplementary data of interest only to those who 

 would pursue the clinical problems in an extended manner. Only by this 

 course may the vast majority of those for whom this treatise is chiefly 

 intended hope to obtain some picture of the general field of B vitamin 

 deficiencies. 



B Vitamin Deficiencies in the Lower Forms of Life 



Very little is known regarding the natural occurrence of B vitamin 

 deficiencies in organisms other than the vertebrates. In single-celled 

 organisms, the lack of some required B vitamin results in a cessation of 

 growth, although some portions of the metabolic machinery may func- 

 tion for short periods under these conditions. For this reason there is 

 little to be gained from a consideration of the known facts regarding this 

 condition in bacteria and protozoa, aside from certain metabolic de- 

 rangements that might be discussed, as they shed light upon similar 

 situations in the higher animals. Perhaps the nearest approach to such 

 a state among the green plants occurs when some foreign toxic substance 

 inhibits the activity of a growth factor, as in the case of the lycomaras- 

 mine inhibition of a strepogenin activity in the tomato (p. 260). Labora- 

 tory-induced deficiencies have been produced in at least one lower animal, 

 the rice moth as previously mentioned (p. 314), it having been rendered 



