The cod is found mainly in waters that bathe the coast of Norway, the Lofoten archipelago, Spitzbergen and Iceland, as well as the Arctic coasts of Russia and Canada. However, the main fishing areas are located on the coast of Norway, the Lofoten archipelago, Spitzbergen and Iceland. The oil is less important than fish meat and is squeezed or extracted from fresh or frozen livers. The cod can live up to 20 years, and can grow up to 1.3 m in length and can weigh 40 kg.

The oil is clear, oily, highly fluid and strong yellow or golden yellow (cod liver oil medicinal) or brown (veterinary cod liver oil) liquid, with a characteristic smell and taste of fish. It is rich in polyunsaturated fatty acids, with 4-6 double bonds. Cod liver oil also contains large amounts of vitamins A and D. In contrast, the oil only contains a small amount of self-oxidizing vitamin E.

Due to its high content of polyunsaturated fatty acids, cod liver oil is of great importance in nutritional physiology. It is used for the prevention and treatment of arteriosclerosis and cardiovascular diseases (Eskimos do not usually have heart disease despite taking many calories and having a diet rich in lipids). In its therapeutic form, cod liver oil is used to treat the deficiency of vitamins A and D (prophylactically for protection against rickets). For oral intake, cod liver oil usually has seasonings and / or is administered in the form of cod liver oil emulsions.

In addition, cod liver oil is used as an ointment for the treatment of wounds. Another use, totally different, is its use in animal feed and in specialized chemical industries, where it is used as a dehydrating agent in the production of varnish and paint. In these areas, veterinary cod liver oil is mainly used, rather than medicinal.