New Zealanders' long-standing love affair with cod liver oil

... diseases such as rickets, caused by a lack of Vitamin D . " The early mixtures probably contained very little vitamin A because it is easily broken down when exposed to the air and light. Vitamin D was much more robust and survived the early crude ...

http://www.foodnavigator-asia.com/Formulation/New-Zealanders-long-standing-love-affair-with-cod-liver-oil?