The main difference between fish oil and cod liver oil is that fish oil can be made from a variety of fish, whereas cod liver oil is made from cod liver. This alone doesn’t mean there is a significant nutritional difference between fish oils and cod liver oils. Both fish oil and cod liver oil can be processed in ways that impact their nutrition. However, fish oil is cheaper to produce and more nutritionally variable when compared to cod liver oil.
Fish oil vs cod liver oil
The distinction between fish oil and cod liver oil products is somewhat blurred by the fact that cod liver oils often contain fish oil. It is not uncommon to see products called cod liver oil containing large amounts of fish oil. This distinction should be clear on the ingredients list of the label. A good example of this is Seven Seas cod liver oil, shown below.
About 2/3rds of the oil is from cod liver, and 1/3rd is from fish oil. Although the majority of the oil is made from cod liver oil, a significant proportion is fish oil.
Historically, cod liver oil has been known for its health benefits. It is rich in vitamin A, vitamin D, and omega-3 fatty acids. Fish oils can be high in these nutrients, but the quantity will vary depending on the fish.
Many conventionally processed cod liver oils and fish oils will have vitamin D and vitamin A added to the oil to improve the nutritional profile. It is this addition of additional nutrients that blurs the quality differences between cod liver oils and fish oils. This information should be clear from the nutritional information on a product.
Looking again at the Seven Seas label above, you can clearly see that Cholecalciferol (vitamin D) and Retinyl Palmitate (vitamin A) are added to the oil. If the vitamins were naturally occurring, they would not be present on the ingredients list.
Fish oils are more environmentally friendly than cod liver oils. This is because they use a variety of fish, and so their impact on one specific population is limited. Fish oils are also made using smaller fish, such as sardines, which are lower down the food chain.
Cod have been heavily fished and populations did reach low levels a few decades ago. Through strict fishing rules, the population is rising, but the amount that can be fished is still heavily regulated. Cod is primarily caught for its fillets though, not it’s liver. Some fisheries, such as those in the UK will fillet the fish onboard their boats, and throw the rest of the fish (including the livers) overboard as waste. If these livers were used for producing cod liver oil, there is no additional environmental impact.
Cod liver oils and fish oils are nutritionally similar, although fish oils are much broader. Due to the variation in processing and the addition of nutrients, it is not possible to say if one is better for you than the other. Much of this information should be clear from the ingredients list/ nutritional information table on product labels. Fish oils are considered to be more environmentally friendly than cod liver oils, but this is only true to a certain extent. Cod is primarily caught for their fillets, so making oil from their livers doesn’t have a significant impact on their populations. Concerns over the cod population are ongoing, but the restrictions relate to the fillet industry, not the cod liver oil industry.