Studies on the Requirements of the Monkey for Riboflavin and a New Factor Found in Liver

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Abstract
Rhesus monkeys were placed on a riboflavin deficient diet and after 6 to 8 weeks a loss in weight became apparent and soon thereafter a freckled type of dermatitis appeared first on the face, then on the hands, legs and groin. Shortly after the appearance of the dermatitis the hemoglobin, red cells and to a lesser extent the white cell level showed a decrease, a hypochromic normocytic type of anemia developing. With the administration of riboflavin growth was resumed, the dermatitis regressed and the anemia showed some improvement. Excretion studies showed that normal monkeys excrete riboflavin daily at the same range as normal humans and that on a deficient diet the daily output drops to 10–15% of the daily intake. Saturation tests fail when applied as a diagnostic tool to determine riboflavin deficiency in the monkey. Fatty livers which cannot be explained on the basis of inanition were demonstrated in monkeys that had died of riboflavin deficiency. The minimal daily requirement for young monkeys appears to be approximately 25 to 30 μg. per kilogram of body weight. Shortly after the administration of riboflavin to deficient monkeys a plateau was reached in the values for their hemoglobin, red and white cells and weights below normal levels. Iron, “pseudopyridoxine,” 1:20 liver powder, extracted liver residue, and increasing the casein level to 24% proved ineffective in restoring the blood picture and weight to a normal level. However, a factor (or factors) found in whole liver substance was necessary at a level of 3% of the ration for optimum growth and blood regeneration.