Cod liver oil is extracted from cod livers, whereas fish oil is extracted from the body flesh of fish. While both are good sources of the omega-3s EPA and DHA, they provide different ratios—cod liver oil generally contains about 9% EPA and 14% DHA, whereas fish oil generally contains about 18% EPA and 12% DHA.

Essential fatty acids (EFAs) are polyunsaturated fats that our bodies need but cannot produce. Therefore, they must be consumed through food or supplements. There are two families of EFAs: omega-3 and omega-6, which need to be consumed in a balanced ratio. The body must receive a balanced supply of omega-3 and omega-6 EFAs to ensure proper eicosanoids production. Eicosanoids are hormone-like compounds that affect virtually every system in the body—they regulate the inflammatory response, help maintain proper blood pressure and cholesterol levels, and promote fluid nerve transmission. The problem is that, in our modern industrialized food system, omega-3s have become largely absent from the food chain while omega-6s have become overabundant. Even the healthiest diets contain too many omega-6s and not enough omega-3s. Decades of scientific evidence indicates that this EFA imbalance can contribute to a variety of chronic health issues. The most beneficial omega-3s that we’re missing are EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid).