XIII. REQUIREMENTS AND FACTORS 583 



change the amount of nicotinic acid consumed or produced by the micro- 

 organisms, which in turn influences the amount of nicotinic acid available 

 to the host. This may be the true explanation, although Hundley^ has 

 advanced the idea, with some supporting data, that fructose and sugars 

 containing fructose require more nicotinic acid in their metabolism than do 

 glucose and sugars containing glucose. According to this theory, fructose, 

 or a portion of it, may be metabolized in a different manner from glucose, 

 a metabolic pathway which necessitates a greater utilization of nicotinic 

 acid-containing coenzymes, and may thereby increase the dietary nicotinic 

 acid requirement. 



d. Intestinal Synthesis of Nicotinic Acid 



The exact explanation for the effect of various carbohydrates on nicotinic 

 acid requirement is still in doubt. Indeed, much has been written about 

 the role of intestinal microorganisms in supplying the host with essential 

 nutrients. Ellinger^^ has reviewed the extensive and excellent work he and 

 his associates have done, as well as that of other workers, which supports 

 the position that intestinal microbes play an important role in providing 

 nicotinic acid for the host. There is no doubt whatsoever that bacteria, 

 such as are found in the intestine, can and do synthesize nicotinic acid, but 

 on the other hand they may also consume and destroy it.^'^' ^^ There is also 

 no doubt that dietary variations such as changing the type of carbohydrate 

 will alter the microbial population of the intestine and will change the 

 amount of free nicotinic acid found in the intestine, as shown by the nu- 

 merous studies on carbohydrates cited previously. 



The essential question is whether any of these changes result in any 

 substantial difference in the nicotinic acid economy of the host. The evi- 

 dence is conflicting. Ellinger and associates have found that some sulfa 

 drugs, but not others, taken orally result in a substantial decrease in 

 urinary N^-methylnicotinamide excretion. ^^- '^° There are clinical reports of 

 nicotinic acid deficiency being induced by oral "sulfa" drugs or anti- 

 biotics.^i ■ ^2 On the other hand, numerous attempts to produce nicotinic 

 acid deficiency in animals by means of sulfa drugs have been unsuccessful. 

 Several investigators have found no decrease in the urinary excretion of 

 N'-methylnicotinamide or other nicotinic acid metabolites after sulfa drugs 



«8P. Ellinger, Experentia 6, 144 (1950). 



6' S. A. Koser and G. R. Baird, /. Infectious Diseases 75, 250 (1944). 



6»R. Benesch, Lancet I, 718 (1945); Prensa med. {Argentina) 33, 1335 (1946). 



«9 P. Ellinger, R. A. Coulson, and R. Benesch, Nature 154, 270 (1944). 



^o P. Ellinger, R. Benesch, and W. W. Kay, Lancet I, 432 (1945). 



" S. W. Hardwick, Lancet 250, 267 (1946). 



" P. Ellinger and F. M. Shattock, Brit. Med. J. II, 611 (1946). 



