Prevention of the injurious effects of excessive cod-liver oil by its fortification with vitamin E.

The injurious effects of dietary excess of cod-liver oil, and the role of the oil both as a source and antagonist of vitamin E, have been discussed in previous communications (Moore, Sharman & Ward, 1958a, b, 1959). According to chemical estimation a specimen of medicinal cod-liver oil contained about 10 mg u-tocopherol/Ioo g. This finding implied that if rats were to be given the oil as 10% of their diet they would receive about four times their minimum requirement of vitamin E, as far as could be judged from the results of previous measurements of the requirements of other rats which had received a basal diet containing lard. Support for the chemical result was obtained in a biological test, in which the unsaponifiable fraction of the cod-liver oil was given to rats fed upon a diet containing lard. When the whole oil was included in the diet, however, most of the signs of avitaminosis E were not prevented. This effect was presumably due to the presence in the cod-liver oil of highly unsaturated fatty acids, which are known to be antagonistic to vitamin E. The ill effects of the cod-liver oil were prevented by adequate weekly doses of m-a-tocopheryl acetate administered separately from the main diet. The object of this investigation was to find whether the injurious effects of cod-liver oil can be prevented by fortifying it with u-tocopherol and, if so, what concentration of the vitamin is required for this purpose. The need for inquiry into these points was emphasized by the finding of Mackenzie, Mackenzie & McCollum (1941) that or-tocopherol had to be administered to rabbits at an adequate time interval before or after dosing with cod-liver oil in order to exert its action in preventing muscular dystrophy.