1912.] 



The Metabolism of Lactating Women. 



105 



prominently emphasised than any other, it is that carbohydrates play a 

 more important part than as simple sources of available energy. Inci- 

 dentally, it may be mentioned that, even as sources of energy, the work of 

 Landergren(ll) made it clear that the body preferred carbohydrate to other 

 substances. The excretion of /3-oxy butyric acid and allied bodies in abnormal 

 carbohydrate conditions makes it apparent that carbohydrate is necessary for 

 the adequate performance of katabolic changes of fatty acids. Further, 

 evidence has accumulated, since Liithje(12) first advocated the theory, to 

 show that carbohydrate is necessary for the synthesis of proteins from the 

 amino-acids by the bioplasm of the animal. 



Again, there is abundant evidence from the number of toxic substances, 

 such, for instance, as phenol and camphor, which are excreted by the 

 body in combination with glycuronic acid, that the poison neutralising 

 powers of the body are largely dependent upon carbohydrates. In support of 

 this fact, also, may be mentioned the experiments of Hildebrandt (16), who 

 demonstrated the innocuous effects of an otherwise lethal dose of thymotin 

 piperidid, if administered with dextrose or cane sugar. 



These few instances show the importance of carbohydrate in physiological 

 activity, and it would appear that nearly all the metabolic processes of the 

 body, with which we are familiar, become abnormal both when it is absent 

 and when it cannot be used. It is not, therefore, contrary to expectation if 

 creatin metabolism, which is a comparatively recent innovation in biochemical 

 development, and not even constant in different mammals, shows signs of 

 abnormality when the carbohydrate stores become unavailable. But it seems 

 to me that evidence of a different nature to that already adduced must be 

 established before creatin can be as directly related to carbohydrate in the 

 body as some would have us believe. 



As regards fatty acid metabolism, it is generally agreed that not only 

 does deficiency of carbohydrate in man necessitate the excretion of 

 /3-oxybutyric acid, but also the excretion of this latter substance is a reliable 

 indication of abnormal carbohydrate metabolism. Can this test be applied 

 to creatin and carbohydrate ? It is an undoubted fact that abnormal 

 carbohydrate metabolism is accompanied by an excretion of creatin. Does 

 the excretion of creatin mean deficient available carbohydrate ? The studies 

 of creatin excretion by puerperal women, above described, lend no support 

 to the view that carbohydrate is not abundant and available. Again, it is 

 impossible to stop herbivorous animals like rabbits and cattle from excreting 

 small quantities of creatin, no matter how much carbohydrate is eaten. 

 Finally, it may be mentioned that the creatinuria in a case of cyclic 

 vomiting recently described (17) could not be cleared up by feeding with 



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