Human Riboflavin Requirement Estimated by Urinary Excretion of Subjects on Controlled Intake

Abstract

Six of 10 [female][female] on diets containing approx. 0.5 mg of riboflavin per day developed signs of ariboflavinosis. While symptoms were present, the [female][female] excreted 30-160[gamma] of riboflavin in the urine per day. Dietary supplements of riboflavin increased the urinary excretion over a period of several days and finally maintained a fairly steady level for each level of riboflavin supplement. On 0.035 mg. per kg. body wt. per day, the urinary excretion was 140-186[gamma] and on 0.05 mg/kg. 793-1295[gamma] per day. 7 women without symptoms and eating a general varied institutional diet excreted 130-800[gamma]/day. The amts. of riboflavin unaccounted for by urinary excre-tion at the levels of intake from 0.035 to 0.085 mg/kg. varied from 28 to 53[gamma] per kg. body wt. These data indicate that 3 mg. riboflavin per day are sufficient for an adult.