A Study of the Riboflavin and Thiamine Requirements of Children of Preschool Age

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Abstract
The average daily urinary excretions of riboflavin and thiamine of two preschool children were determined on various levels of intake. One-hour fasting excretions, 4- and 24-hour returns of test doses of both vitamins and thiamine content of the blood were determined at each intake level. The 1-hour fasting excretions and the 4- and 24-hour test dose returns were found to correlate well with each other and with the intake. There was less evidence of correlation of blood thiamine with both the intake and the other tests of nutritional status. It seems, therefore, that the 1-hour fasting excretion and the return of an oral test dose can be used equally well in determining the nutritional status with respect to riboflavin and thiamine but that the blood thiamine level is less reliable. The riboflavin requirement was considered to be the lowest level at which the daily excretions neither decreased nor increased progressively. In the case of thiamine, the requirement was based on an average daily excretion of 20% of the intake, decided increases in the fasting 1-hour excretions and test dose returns, and blood levels of 7.0 μg. or more per 100 ml. Riboflavin and thiamine intakes of approximately 0.50 mg. per 1,000 Cal. satisfied these criteria and therefore appeared to meet the needs of the subjects used in this study. Until such time as more data are available, the return, in 4 hours, of 20% of a test dose of riboflavin and of 12% of a test dose of thiamine or fasting 1-hour excretions of 9 μg. of riboflavin and 6 μg. of thiamine might be considered indicative of satisfactory nutritional status with respect to these vitamins.