Chapter XI D 



BIOLOGICAL ACTIVITIES OF OTHER NUTRITIONAL 

 FACTORS OF DOUBTFUL STATUS* 



Choline 

 Introduction 



The presence of choline as an integral structural unit as phospholipides 

 was recognized soon after the middle of the last century; lecithins and 

 sphingomyelins from both plant and animal sources were found to con- 

 tain the substance. The nutritional importance of choline was not demon- 

 strated until relatively recently. 



In a series of investigations which followed the discovery of insulin by 

 Banting and Best in 1922, it was found that the administration of 

 lecithin prevents the abnormal accumulation of fat in the livers of de- 

 pancreatized dogs injected with insulin. 1 - 2 - 3 Subsequently it was shown 

 that the development of fatty livers in rats maintained on a high-fat, 

 low-protein ration can be prevented or cured by the inclusion of choline 

 in the diet. 4 The lipotropic action of lecithin was therefore attributed to 

 the presence of choline in its structure. 



It is now known that a dietary deficiency of choline may cause a 

 variety of metabolic disturbances. These effects are discussed in detail 

 in several excellent review papers. 5, 6 - 7 For rats, a lack of choline results 

 in cessation of growth, infiltration of fat in the livers, and hemorrhagic 

 degeneration of the kidneys. For chicks and turkey poults, a choline 

 deficiency causes cessation of growth and perosis or "slipped tendon 

 disease." 



In addition to its involvement in animal and avian nutrition, choline 

 is required as a growth factor by a number of microorganisms including 

 certain strains of pneumococci (Types I, II, III, V, VIII) s - 9 and "choline- 

 less" mutants of Neurospora crassa. 10 ' n 



Studies dealing with the choline molecule suggest that the metabolic 

 effects of choline may be divided into two groups: (a) those which de- 

 pend on the effectiveness of choline as a source of the "transferable 

 methyl group," and (b) those which depend on the presence of the intact 

 choline molecule. 



* By Thomas J. Bardos, Lorene L. Rogers, and A. D. Barton. 



703 



