So I decided to write a little bit about the differences between Cod Liver Oil (CLO) and Fish Oil (FO). In reality, these two products have very little in common, and cannot be used in place of one another.
I'll start with Fish Oil, which has gained popularity recently on the market as a ''good'' source of the essential fatty acids EPA and DHA. What we need to realize about fish oil is that, it is not a food in the sense that FO is not procured strictly for the oils of the fish. FO is actually an industry byproduct, taken from after the manufacturing process of removing the fillets, heating the fish carcasses to high temperatures and using high pressure vats to separate out the oils from the other fish solids, which are used in things like cat food.
These processes are inherently damaging to the vulnerable and delicate DHA and EPA oils, which are polyunsaturated and highly likely to be damaged by oxidation. Before that Fish Oil has even finished being separated from the fish, it is already rancid and useless (or worse) to your body.
Cod Liver Oil is in itself a food in the sense that cod, skate, and other fatty cold water fishes are caught for the purpose of making Cod Liver Oil. This is also a food that has been prized by traditional societies for hundreds of years for it's health promoting properties.
The livers of the fish are taken after the harvesting of the fillets, a very quick process traditionally done by hand very soon after catching the fish to ensure freshness. The livers are either put into vats right there on the boat, or chilled for transport to a facility.
The most ancient way of harvesting the oil from the livers of these fish is by fermenataion. The fermentation process breaks down the cells and structures of the liver, allowing the oils within to rise to the top of the barrel of fermenting livers. This 'top oil' is extremely rich in Vitamins A and D, which act as potent antioxidants to protect those delicate DHA and EPA oils from oxidation.
Newer types of processing include cold pressing or chemical extraction of these oil. Of the two, cold pressing is preferred to chemical extraction.
Cod Liver Oil is unique in that it provides vitamins A and D in the most useful ratios to the body. We know that supplementing only vitamin D will deplete Vitamin A, and vice versa. Supplementing only Vitamin A and D without K2 will deplete that essential vitamin as well. It is recommended to use Cod Liver Oil with a diet high in grassfed butter, ghee, cheese, and organ meats like liver, to ensure optimal balance of all the fat soluble vitamins.
In Conclusion, Fish Oil should be avoided. The oils in these products are rancid, useless to the body and may even be damaging.
Cod Liver Oil, provided it is either from fermented fish livers or cold pressed, contains high levels of unaltered Vitamins A, D, EPA and DHA oils which are protected by the antioxidant vitamins.