Hypervitaminosis E in the Chick

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Abstract
The effects of feeding excessive amounts of vitamin E ranging from 220 to 2,200 IU per kilogram of diet were studied in relation to various metabolic parameters. Growth rate was not affected by a level of 1,000 IU, but was depressed by 2,200 IU of vitamin E per kilogram of diet. Thyroidal hypertrophy in response to thiouracil was reduced when the diet supplied 220 IU/kg. This level of vitamin E also depressed thyroidal uptake and release of 181I. The respiration rate of skeletal mitochondria isolated from chicks fed 2,200 IU of vitamin E for 55 days was only two-thirds that of mitochondria from control chicks. Bone calcification was depressed when excess vitamin E was administered to chicks fed either calcium-deficient or vitamin D-deficient diets. Bone calcification was affected by excess vitamin E administered through the diet or by injection. It was concluded that excess vitamin E increased the requirement for vitamin D. Vitamin E at a dietary level of 2,200 IU/kg induced reticulocytosis and lowered hematocrit values. A lengthening of prothrombin time occurred when excess vitamin E was fed which was rapidly reversed by injection of vitamin K indicating an increased dietary requirement for vitamin K in the presence of excess vitamin E. The above findings suggest that excess vitamin E, like the other fat-soluble vitamins, must be considered as potentially toxic.

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