Effects of Dietary Depletion of Riboflavin

Abstract

The effects of diets restricted in riboflavin but otherwise adequate were observed in 15 male subjects. Fourteen other subjects were observed simultaneously as controls. Depletion with respect to riboflavin on a diet of 0.55 mg in 2,200 cal. was maintained for from 9 to 17 months, during which period angular stomatitis, seborrheic dermatitis, scrotal skin lesions, and diminution of ability to perceive flicker were observed. Simultaneous experiments in which the same diet was fed to rats confirmed the inadequacy of the diet. In these animals retardation of wound healing was conspicuous. Studies of the excretion of riboflavin in the urine suggest that the riboflavin requirement of a resting adult is between 1.1 and 1.6 mg per day. A reserve of riboflavin cannot be maintained on levels of intake below 1.1 mg. Since previous studies revealed few abnormalities when the intake of riboflavin was above 0.6 mg per day, it may be concluded that allowances below this amount are insufficient to support normal tissue repair. The type of abnormality then encountered will be dependent upon the trauma, irritation, infection or other injuries to which the tissues are subjected. Changes in the blood levels of lactic and pyruvic acids were not obtained on diets low in riboflavin, as opposed to the marked changes in carbohydrate metabolism observed during thiamine deficiency.