Urinary Excretion of Vitamin C

Abstract

Many authors have demonstrated that vitamin C exists in various organs and fluids of the body. Moreover, it has been shown that in the guinea pig the concentration of vitamin C in the body is dependent upon the intake,^1-4 and that in the tissues of the guinea pig the vitamin C concentration is lower than in species which are not dependent upon a dietary source of this vitamin. 3 In view of such evidence, it was thought worth while to investigate the urinary excretion of vitamin C. The experiments were planned to throw light upon the following questions: 1. Is vitamin C excreted by the urinary route? 2. Is the level of urinary excretion proportional to the intake or is it a measure of excess vitamin ingestion? 3. Is there a difference in urinary excretion between species which do and those which do not require a dietary source of the vitamin?

As far as we are aware, very little work on this subject has been reported, von Euler and Malm 5 state that they were unable to detect vitamin C in normal, febrile or diabetic urine. On the other hand, van Eekelen and his associates 6 found that urinary excretion ran parallel to intake, but since these authors do not give any figures, no comparison between species can be made on the basis of their work.

The method employed was that of Birch, Harris and Ray, 7 based on the titration of ascorbic acid against 2:6 dichlorophenol-indophenol. Since urine is known to contain only traces of the compounds (glutathione and other sulphydryl compounds) which form the chief source of error in the application of this method, it seemed safe to consider any reducing substance found in urine to be ascorbic acid.