The majority of cod liver oil available in the United States is Norwegian cod liver oil. It is sourced from many varieties of cod and cod fishing is an important industry in Norway.
This page looks at how cod liver oil is made and four important factors to consider when looking for a high quality cod liver oil.
How is Norwegian Cod Liver Oil Made?
In recent years, particularly in Norway, new cod liver oil manufacturing
processes have been developed to greatly reduce or eliminate the potential for oxidization; that remove any heavy metals or PCBs to undetectable levels (all cod liver oil sold in the USA and UK/Europe is heavily tested for these); and that minimizes the fishy taste and odor.
All of these are good things, but with these new manufacturing processes there is a concern that some of the very nutrients we buy cod liver oil for may be damaged, or in some cases completely removed in the process.
Molecular distillation is used to remove impurities and potential toxins while concentrating the important EPA and DHA omega-3 fatty acids. It seems the best results are produced when this is done for a shorter time under a high vacuum. Some longer molecular distillation processes may damage the oils and possibly even create trans fats. A good cod liver oil should have a quick molecular distillation with a low ‘heat residence time’.
Vitamin A and Vitamin D in Cod Liver Oil
Another concern is the kind of vitamin A and vitamin D found in cod liver oil. Modern manufacturing methods will remove much of these important health nutrients in processing. The naturally occurring vitamin A and vitamin D can, however, be collected during the processing and added back in later. Keeping in mind that we are looking for a vitamin D to vitamin A ratio of at least 1 to 10 and preferably closer to 1 to 5, this seems like the best option to me.
Other possibilities are cod liver oils manufactured to retain some of the naturally occurring vitamins with nothing added back later. This sounds good, but unfortunately it seems to be difficult to do and much of the vitamin content is lost, particularly vitamin D. Cod liver oils produced in this way often have ratio of 1 to 25 or higher for vitamin D versus vitamin A and can’t be recommended.
Far more common, are cod liver oils produced with processing that removes the majority of the naturally occurring vitamin A and vitamin D, and then adds back synthetic versions later on. This is usually in the form of retinal palmitate for vitamin A and cholecalciferol for vitamin D. Many of the cod liver oils available in the USA fall into this category. Personally, I think it’s worth paying a bit more for the naturally occurring vitamins.
In summary, looking for good quality cod liver oil, there are a few factors to consider:
- Does the molecular distillation process involve a ‘low heat residence’ time to minimize damage to the oils?
- Does the cod liver oil provide a good amount of EPA and DHA omega-3s? I’d be looking for at least a gram of combined omega-3 fatty acids, ideally two or more per dose.
- Is the ratio of vitamin D to vitamin A at least 1 to 10 and preferably closer to 1 to 5?
- Are the vitamins derived from the fish itself or are they synthetic?
Carlsons make a high quality Norwegian cod liver oil that, according to the company’s literature and nutritional information, matches with all four of these points above. It is at a low price at Amazon in regular 250ml and large 500ml bottles in orange oil or lemon oil flavored liquid.
You really can’t taste any fishy taste at all with these new flavored cod liver oils, but if you prefer capsules there are some great options in the low vitamin A caps and discounted softgels. There are many more cod liver oil options in the previous article on Where to Buy Cod Liver Oil as well.