Excretion of Thiamine and its Metabolites in the Urine of Young Adult Males Receiving Restricted Intakes of the Vitamin

Abstract : Eight young men consuming a 2800-kcal diet consisting of 80 g protein, 100 g fat and 400 g carbohydrate and providing 0.11 to 0.18 mg thiamine/day, developed clinical symptoms of thiamine deficiency in 9 to 27 days. Thiamine excreted in the urine decreased to less than 50 micrograms/day at the sixth day to the undetectable levels by the eighteenth day of depletion. Low-level repletion (0.54 to 0.61 micrograms/day) for 12 days failed to produce detectable levels of thiamine in the urine. Red blood cell transketolase activity declined with progressive thiamine deficiency and returned to normal levels with low-level repletion. The excretion of the pyrimidine and thiazole moieties of thiamine as metabolites of the vitamin appeared to increase above the levels found with the use of a diet with sufficient thiamine (about 2 mg/day), and was reduced to control levels following low-level repletion. The pyrimidine moiety in the deficient individual appears to be further catabolized. There appears to be a body store of thiamine which is utilized during a period of deficient intake. Serum cholesterol, nonesterified fatty acids, blood phospholipids, creatinine and hematocrit did not change appreciably during thiamine deficiency. The biochemical pattern for thiamine deficiency in human adults is described. (Author)