Effect of Dietary Protein Level on Pyrido-Xal Content in Tissues and Excretion of Pyridoxic Acid Into Upine in Normal or Pyridoxine-Deficient Rat

Rats were fed diets containing different levels of protein with or without pyridoxine. The growth of rats receiving the high-protein diet without pyridoxine was severely retarded. The total contents of pyridoxal in tissues and pyridoxic acid in urine were measured and the following results were obtained. In the liver, the pyridoxal content of rats receiving the high-protein diet was higher than that of rats receiving the low-protein diet, but in other tissues tested, the reverse situation was found. The pyridoxine-deficient rat fed on the high-protein diet showed severe decreases of pyridoxal levels in all the tissues examined. The pyridoxine-deficient rats excreted more pyridoxic acid in the urine than the intake, regardless of the protein levels of the diet. Some relationship between protein intake and excretion of pyridoxic acid is discussed.