The Urinary Excretion of Riboflavin by College Women

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Abstract
The urinary excretion of riboflavin by college women was studied on non-restricted diets, after an oral test dose, and on controlled riboflavin intakes. The urinary excretions for twenty women on self-selected diets ranged from 0.06 to 0.92 mg in 24 hours. The 1-hour fasting excretion, the 4-hour and the 24-hour excretions after an oral test dose of 3 mg were significantly related with the average daily urinary riboflavin excretion for 3 days preceding the test dose administration. From three to nine subjects were studied at each of the following riboflavin intakes: 0.79, 1.04, 1.26, 1.62, 2.23 and 2.72 mg daily. The average urinary riboflavin for the last 3 days of each period of controlled diet were as follows: 0.07, 0.16, 0.13, 0.32, 1.18 and 1.31 mg per 24 hours. The percentage of a 3-mg test dose excreted in 24 hours following the periods of controlled intake was, respectively, 22, 30, 27, 31, 55 and 56. A comparison of the data from this study and the data reported in the literature indicated that 1.3 to 1.5 mg riboflavin per day were adequate for women with a requirement of 2100 to 2300 cal.