Oil obtained primarily from the liver of the Atlantic cod and related fish.
It is principally a mixture of the glycerides (see glycerol ) of many fatty acid s, but its minor constituents, the fat-soluble vitamin A and vitamin D , give it its importance. It was once used to treat and prevent rickets , but the widespread fortification of milk with vitamin D in the United States and Europe beginning in the 1930s eliminated rickets as a significant public health problem. It is still used as a remedy for joint pain caused by arthritis and as a preventive of cardiovascular disease, although these benefits have not been proven scientifically. It is also used in feeds for poultry and other animals.