Vitamin B2 Deficiencies as Affected by Dietary Carbohydrate

Abstract

When lactose in sufficient amount is incorporated in the basal diet, of the three necessary factors now recognized in the vitamin B₂ complex, both flavin and vitamin B₆ need not be given separately and are apparently elaborated in the intestine of the animals. The filtrate factor however must be given in order to obtain normal growth. In no case did dermatitis develop in lactose-fed rats even when the proportion of lactose was lowered to 30%, but a large proportion of the rats developed cataracts. The severity of the cataract occurrence was mitigated when all the vitamin B factors were supplied, and this prophylactic effect seemed to inhere in the filtrate factor particularly. When cornstarch is used as the carbohydrate of the basal diet, dermatitis and relative failure of growth result unless B₆ and flavin are supplied. The filtrate factor appears to be present in limited amount in the starch or to be produced in the intestine when cornstarch is used. No cataracts occurred on any of the starch or sucrose diets. When sucrose is used as the carbohydrate of the basal diet, earlier and more severe dermatitis and growth failure occur unless all three of the factors are supplied. Better growth response was obtained with sucrose than with starch when one or more of the factors was supplied and better response with starch than with lactose. Graying of the hair of black rats was seen on most of the diets which lacked the filtrate factor and this was prevented or cured by administration of the rice bran concentrate which was used as source of the filtrate factor. Blood and urine reducing sugar of the rats on lactose were much increased over that of the starch-fed group. Urine calcium was also much increased in this group. The sucrose diets produced normal blood sugar values but when one or more of the B₂ factors was lacking, high urine sugars. Some clue to the mode of action of these factors may be found in this behavior.