F1 AND F2 OF NAJJAR AND HOLT IN THE URINE OF NORMAL YOUNG MEN 1

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Abstract
The usefulness of routine estimations of the fluorescent pigments F1 and F2 as an adjunct to nutritional surveys has been studied in normal young men. Precautions for the preservations of specimens are described. F2 appears to be stable in post-absorptive urines for a week but after oral doses of nicotinamide the amt. of urinary F2 appears to rise during storage. Conclusions from studies on 169 subjects are that the presence or absence of F1 in the urine of normal young men bears little relation to the nutritional state although its excretion is sometimes increased by ingestion of thiamine. The level of urinary F2 correlates reasonably well with other evidence on the nicotinic acid stores. Occasional men receiving adequate nicotinic acid excrete no F2 and one man after fasting 16 days was excreting large amts. The usual response to test doses of nicotinamide is an increase in F2 excretion but in view of the exceptions, the urinary level of F2 must be interpreted with caution, and should not be used as the sole criterion of the adequacy of diets with respect to nicotinic acid.