If you want to increase your intake of omega 3 fatty acids, you should take fish oil and not cod liver oil. They are not the same. Cod liver oil is extracted from cod liver and is very rich in Vitamin A and D, but doesn't contain lots of omega 3 (EPA and DHA).
Fish oil on the other hand is extracted from the tissues of cold water fish and is one of the richest sources of EPA and DHA. However, fish oil contains only very little vitamin A and D.
It is also known, that fish oil lowers the blood concentration of Vitamin E, so it's a good idea to take extra Vitamin E when you add fish oil to your diet. Most fish oil supplements contain already Vitamin E.
When should you take cod liver oil?
In the cold winter months when you don't have much sun exposure you might lack Vitamin D. At these periods it might be a good idea to take cod liver oil in order to increase your Vitamin D levels.
