Minimum Daily Requirement of Rabbits for α-Tocopherol

During the past year we have been studying the vitamin E requirement of rabbits for the cure and prevention of nutritional muscle dystrophy. Recently, MacKenzie and McCollum 1 reported that the rabbit requires 0.7 to 1.0 mg of α-tocopherol per kg of body weight, but this does not quite agree with our Findings. In our experience, rabbits made dystrophic on the Goetsch-Pappen-heimer diet 13 were cured by the daily oral administration of synthetic dl-α-tocopherol acetate in quantities ranging from 0.18 to 1.0 mg per kg of body weight, with most of the cures resulting from doses of 0.2 to 0.5 mg (as free alcohol).

We found that a definite correlation exists between the higher requirements and the total α-tocopherol intake. When animals with an apparently high vitamin E requirement were subjected to a new test on a smaller total tocopherol intake, their requirement dropped to a lower level (values ranging from 0.2 to 0.4 mg per kg). These findings suggest that the higher values, as well as the wider range of variation in the requirement values, are not so much an outcome of individual variability in the need of the tissues for vitamin E as of variations in the efficiency of absorption, in ability for storing and in the rate of destruction of the vitamin.

In addition to the experiments with diet 13, we also fed rabbits our diet X 113 from which vitamin E is removed by an exhaustive extraction with lipid solvents. Rabbits on this diet become dystrophic as readily as on diet 13, in which vitamin E is destroyed by oxidation with FeCl₃ and rancid fat. We treated rabbits made dystrophic on diet X 113 with much smaller total amounts of α-tocopherol than were used with most animals fed diet 13.