JAMA. 1954;154(1):60. doi:10.1001/jama.1954.02940350062016.
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Although the indispensability of vitamin A in the diet has long been accepted, the precise mode of its action in the organism still remains to be demonstrated. To be sure, distortion of normal histogenesis and widespread metaplasia are recognized as more or less characteristic sequelae of the deficiency of this food factor; yet detailed information with respect to its influence on the chemistry of cellular processes is not available. There are, however, facts about vitamin A that will ultimately contribute to a better understanding of the mechanism of its action.

Inasmuch as the vitamin has the chemical structure of an alcohol, its existence in liver oil partially as an ester1 might be expected; in one study2 after experimental animals had been fed a concentrate of fish liver oil containing almost all the vitamin in the ester form, the vitamin A was largely present in the intestinal mucosa in


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