Relation of Protein and Fat Intake to Growth and Corneal Vascularization in Galactoflavin-Produced Ariboflavinosis

Abstract

The influence of dietary casein levels ranging from 5 to 74% and of fat levels ranging from 0 to 20% upon rats on high and low riboflavin intakes with and without galactoflavin supplementation was studied with regard to growth, food consumption, survival time and corneal vascularization. On riboflavin-high diets containing 20% lard, weight increases ran roughly parallel to the protein level up to 30%. With 74% casein, the weights were similar to those on 18%. The daily caloric intakes were about 28 cal. for the animals on 5% casein, eventually about 50 for those on 18 or 30%, and about 40 for those on 74%. On riboflavin-low diets with 18 or 30% casein, food consumption was about two-thirds and growth one-third to one-half those of the controls. With 5% protein, there was no difference in growth or food consumption between the animals on high and low riboflavin intakes. With 74% casein, the food consumption was about the same as that of animals on 18%, but those receiving 74% grew better. Animals on all riboflavin-low diets with 3 to 5 mg of galactoflavin daily rapidly developed the deficiency state. Regardless of the protein level, they lost weight almost immediately; those on 74% lost the most. The daily food intake was about 15 cal.: animals on the highest protein level showed the lowest consumption. The survival time of all groups was only about 30 days; those on 74% protein died first. With simultaneous galactoflavin and riboflavin supplements, no toxic effects on growth, food consumption or fertility were noted. It was concluded that riboflavin and protein are mutually limiting factors and that, at a high level, protein may become toxic in riboflavin deficiency. High dietary fat levels accentuated the deficiency state, the galactoflavin data suggesting that this effect is a true metabolic one and that protein utilization in riboflavin deficiency is probably better in the absence than in the presence of fat. Corneal vascularization occurred equally in all animals on 5% casein, regardless of riboflavin or galactoflavin intake. Higher protein levels delayed the development of the condition. On fat-free diets its onset was further delayed. The conclusion was drawn that the possibility cannot be ruled out that riboflavin deficiency plays a more specific part in this type of corneal vascularization than is often believed.