Identity of Natural Vitamin D from Different Species of Animals

Abstract

BILLS, Massengale and Imboden¹ have found that one rat unit of blue-fin tunny liver oil in chicks has only 15 per cent of the antirachitic effect of one rat unit of cod liver oil, whence they conclude that the two forms of vitamin D are different. However, Dols² demonstrated that the antirachitic effect of these two forms of vitamin D in chicks is the same, the necessary dose being about 80 international D units a day for each chicken. Before the results of Dols were known to us, we had running a great number of tests to investigate whether there is any difference between the vitamin D of different species of animals. (The fact that there is another form of natural vitamin D found in green plants and accompanying the free fatty acids³ is not discussed here.)