The presence of vitamine A in the peel of common citrous fruits

Abstract

About a year ago, preparations of orange peel were added to a diet otherwise free from the fat soluble vitamine. The possibility that such preparations might contain fat soluble A was based on the hypothesis of Steenbock that the fat soluble vitamine is a yellow vegetable pigment or a closely related chemical compound. The peels used for a determination of their fat soluble vitamine content were faultless and of the deepest yellow color. The outer surface of the dried peels was grated enough to break the tiny pockets which contain the yellow oil. Peels and gratings were then extracted on the water bath with ether and alcohol. These extracts were evaporated down to dryness. The gummy mass thus obtained was stirred thoroughly into a diet otherwise free from fat soluble vitamine and then fed to a number of white rats. The results yielded indubitable evidence that the waxes and oil of the orange peel are rich in the fat soluble vitamine. On this diet young rats have matured, mated, and raised young. Control experiments showed the diet, without the preparation of orange peel, to be free from fat soluble A. Experiments now in progress indicate that similar preparations made from lemon and grape fruit peel likewise contain the fat soluble vitamine.