THE UTILIZATION OF RIBOFLAVIN GIVEN PERIODICALLY TO THE RAT APART FROM THE DIET

Abstract

Male weanling rats were depleted of riboflavin reserves and given limiting amounts of riboflavin in the diet throughout the day, or at 1-, 2-, and 4-day intervals by stomach tube. Riboflavin given once a day by stomach tube was as efficiently utilized for growth as the same amounts of the vitamin given daily in the diet. Animals given equivalent amounts of riboflavin at 2- and 4-day intervals, however, showed a stepwise reduction in weight gain, food intake, and efficiency of food utilization. The efficiency of utilization of riboflavin given every 4 days varied with the size of the dose.In metabolic studies, rats given riboflavin every 4 days excreted more of a dose of C¹⁴-labelled riboflavin in the urine and feces, and retained less of the dose in the liver and carcass, than those given the vitamin daily. Administration of riboflavin at 4-day intervals had no effect on liver and carcass riboflavin levels.It was concluded that riboflavin given as a single daily dose is as well utilized by the rat as that consumed with the diet in several small doses over a 24-hour period. Administration of the vitamin at greater than daily intervals reduced the efficiency with which it was utilized.