An Unknown Factor with Vitamin a Activity Distilled from Lard

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Abstract
The nutritional effects on rats of the distillate and residue fractions of molecularly distilled lard were studied. When vitamin A-free diets containing the residue fraction as the fat source were supplemented by distillate, or when this material was injected, the animals could be protected against the signs of vitamin A deficiency. The protection given by 2% distillate in the diet seemed nearly complete and was much better than that provided by weekly injections of 7.5 units of vitamin A palmitate. These results could be explained neither by the presence of vitamin A in the distillate nor by a nonspecific anti-oxidant action of the distillate. It was therefore concluded that lard contains a factor with vitamin A-like activity but which is chemically different from the known forms of vitamin A. The significance of this factor with respect to specific epithelial lesions in animals on vitamin A-low rations, to vitamin A bioassays, and to a “fat minimum” in the diet has been discussed.