whole foods will always have more balanced nutrition profile than “extracted” products (like cod liver oil). it’s fine to have a serving of whole cod liver 2-3 times a month. it is an excellent source of some nutrients like vitamin A, B12, iron, zinc, omega 3 fats, and has a good amount of protein as well. remember that everything, even water, is toxic at high enough levels. in the case of organ meats like liver, frequent consumption (a four ounce serving twice or more every week) can cause toxicity of some nutrients like vitamin A and zinc.