XII. REQUIREMENTS AND FACTORS INFLUENCING THEM 



401 



the evaluation of rihollaxiii nutrition. ( )l(lliain ct alJ'^ and Pollack and 

 Bookman^^ have shown that increased amounts of riboflavin are excreted 

 by sul)jects in marked negative nitrogen balance. Therefore, in those spec- 

 ial cases where tests for riboflavin excretion are made on patients who are 

 catabolizing abnormal amounts of their own tissues, the excretion data may 



TABLE IV^5 



Comparison of Ukinary Excretion with Daily Intake of Riboflavin. Except 



FOR Those on the 0.55-Mg.-Diet, the Data Listed Represent Plateau 



Levels Which Were Reached in 10 Weeks or Less on the 



Intake Designated" 



" At an 0.85-mg. intake or higher the figures obtained at 15 weeks remain at the same level for at least 2 

 years more. At a 0.75-mg. intake most of the subjects remained at the level designated for 6 months, at which 

 time they were supplemented. A few individuals who remained longer on this diet showed no further change, 

 but whether or not their excretions would have decreased further with additional time is not known. 



** The time of analyses for diets providing 0.75, 0.85, and 1.1 mg. of riboflavin represents the first time 

 plateau levels were obtained which were repeated during subsequent months. The results recorded for the 

 diets providing 1.6, 2.15, and 2.55 mg. are averages of voluminous data obtained during the period of time 

 indicated. 



' After 7 weeks. 



"* These results were obtained from the same individuab who received the 2.55-mg. intake. After 62 weeks 

 on this intake, their supplementation was further increased to provide a 3.55-mg. intake. The values for the 

 24- and 4-hr. excretion periods were obtained IVi and .3 weeks, respectively, after the change in supplementa- 

 tion. 



be higher than normally expected. There is a high degree of agreement in 

 the results of excretion studies by different laboratories of subjects on low 

 levels of riboflavin intake,''^ • "-®- but the variations are greater when the 



" H. Oldham, E. Louiuls, and T. Porter, J. Nutrition 34, 69 (1947). 

 *« H. Pollack and J. J. Bookman, J. Lab. Clin. Med. 38, 561 (1951). 

 <*' C. W. Denko, W. E. Grundy, N. C. Wheeler, C. R. Henderson, G. H. Berryman, 



T. E. Friedemann, and J. B. Youmans, Arch. Biocheni. 11, 109 (1946). 

 " R. D. Williams, H. L. Mason, P. L. Cusick, and R. M. Wilder, J. Xutrition 25, 361 



(1943j. 

 " A. Keys, A. F. Henschel, O. Mickelsen, J. H. Brozek, and J. II. Crawford, J. Nutri- 



ion 27, 165 (1944). 

 «» V. A. Najjar and L. E. Holt, Bull. Johns Hopkins Hasp. 69, 476 (1941). 



