Physiological Availability of the Vitamins

Abstract

A biological assay technic has been described for the simultaneous determination of the physiological availability of the water-soluble vitamins, ascorbic acid, thiamine, riboflavin and nicotinamide. The test is based upon the observation that the urinary excretion of the water-soluble vitamins, as such or as their derivatives, parallels the quantity consumed provided that normal test subjects are employed and that the subjects at the time of the tests are subsisting on an adequate diet. A simplified feeding routine is described which extends the applicability of the assay to quantitative studies of problems in human nutrition, particularly those dealing with the factors which contribute to conditioned malnutrition. The dose-response relationships for each of the test vitamins have been found to be linear and the reproducibility of the data superior to that encountered in most animal assays.