The Question of Synthesis of the Antirachitic Vitamin by the Cod

Abstract

Ever since the recognition of the antirachitic factor, the question has been raised as to whether cod fish synthesize this factor or whether the marked potency of their liver oil is due to antirachitic vitamin taken in with the food. Investigations have been few and inconclusive. Wejdling 1 has drawn attention to the fact that diatoms, which may form a part of the diet of the cod, contain the antirachitic vitamin. On the other hand, Bills 2 has demonstrated that caplin, which are consumed in enormous quantity by the Newfoundland cod, are not rich in the D factor, and suggested that some of the vitamin may be formed by synthesis within the fish.

Some years ago we carried out experiments designed to ascertain whether the livers of cod fish which were fed large amounts of non-activated ergosterol by mouth contained exceptional amounts of the antirachitic factor. Cod fish were given, by means of a pipette, 5 feedings of 10 mg. each of ergosterol suspended in cottonseed oil. The fish were kept in tanks in New York Bay and feedings were given at 2-day intervals, the last one being given about 36 hours before the fish were killed. The result may be summarized by the statement that the livers of the fish which received the ergosterol were found, on biological assay, to contain the antirachitic vitamin in no greater amount than the control fish which were kept under similar conditions, but which had not been given ergosterol. Two series of experiments were carried out with the same result.

Last December this subject was approached from a somewhat different point of view. Instead of giving ergosterol by mouth, it was injected intramuscularly. Three injections were given of 1 mg. dissolved in 5 cc. of corn oil; there was an interval of 2 days between each injection and 2 days elapsed before killing the fish.