Vitamin B6 Nutriture Studied in Obese Subjects During 8 Weeks of Starvation

Abstract

Vitamin B₆ nutriture was studied in obese subjects during 8 weeks of starvation. When tryptophan-load tests were given, there was an increased excretion of xanthurenic acid and kynurenic acid in all subjects who had been starving for 2 weeks or longer. The excretion of 3-hydroxykynurenine and of kynurenine was also increased in most subjects during this period. Of the various tryptophan metabolites, the greatest increment in excretion occurred with xanthurenic acid. After 4 weeks of starvation, when a dose of 10 mg of pyridoxine. HCl/day was given for 5 days, the elevated excretion of tryptophan metabolites was reversed; and when the vitamin was given for the first 20 days of starvation, the amounts of tryptophan metabolites excreted remained in the normal range. These observations were taken as evidence that a vitamin B₆ deficiency develops during starvation. There were no significant changes in either the urinary oxalate excretion or the plasma transaminase levels during the course of starvation.