Biochemical assessment of thiamine nutrition in childhood.

The activity of red cell transketolase and TPP-effect were determined in 1028 infants and children, aged 1 month to 14 years, using a micromethod. All the children were healthy and without evidence of malnutrition. Transketolase activity decreased in the second year of life, followed by a constant increase up to the 6th year. Activity did not change in the next four years, then a steady decrease occurred. TPP-effect was not as stable as transketolase activity, and decreased significantly from years 3 to 5 and increased significantly from years 5 to 7. Beginning with year 10, TPP-effect decreased gradually. 6.6% of all children investigated had marginally deficient TPP-effects and 1.3% were biochemically deficient without clinical signs of avitaminosis. A group of 37 adults had transketolase activities and TPP-effect comparable to those of the 13 year-olds. Effect appeared to be marginal in 5.4% and deficient in 2.7%.