Transketolase Activity and Urinary Excretion of Thiamin in the Assessment of Thiamin-Nutrition Status of Indians

Abstract

Red blood cell transketolase activity and urinary excretion of thiamin under basal conditions (2 hr before and 4 hr after a 1 mg load) were studied in normal subjects and subjects suffering from deficiency of the B-group of vitamins. No correlation was found between these biochemical parameters, or between clinical symptoms and any of these indices. Most of the subjects were found to have adequate thiamin nutritional status when judged by the criteria normally used for urinary excretion. In a controlled longitudinal study on human volunteers, RBC transketolase activity and 24-hr urinary excretion of thiamin were studied in relation to dietary intake. After a stabilization period of 2-3 weeks on restricted intake of thiamin (0.1 mg/1,000 kcal), the vitamin supplement was increased to 0.2 mg and 0.4 mg/l,000 kcal, respectively, at weekly intervals. Urinary excretion as well as enzyme activity were studied and were found to be sensitive to dietary thiamin. However, urinary excretion of these subjects was throughout very much higher than expected from the data in the literature, thereby suggesting that different criteria of urinary excretion in Indians may be necessary for nutritional evaluation. Estimates for minimum requirement of thiamin were obtained by plotting the logarithm of dietary intake against transketolase activity or urinary excretion. The minimum requirement for women was found to be between 0.214 and 0.263 mg/1,000 kcal and for men between 0.313 and 0.359 mg/1,000 kcal.