The difference between fish oil and cod liver oil is that fish oil is extracted from the flesh of tuna, herring, cod and other deep-sea oily fish species whereas cod liver oil comes from the liver of the cod fish. Fish oil is rich in omega-3 fatty acids such as EPA and DHA but doesn’t have much vitamin A or D; on the other hand, cod liver oil has less omega-3s but is very rich in vitamins A and D.
Some rumors have pointed out that cod liver oil contains a high concentration of vitamin A, which may pose a potential risk to the human body. This issue stems from the fact that almost all cod liver oil products on the market are supplemented with vitamin A (whether natural or synthetic). There will be a situation where many cod liver oil products are not extracted from real cod liver. Many brands on the market use fish oil extracted from the general fish body (for example, from green carp or haddock), because the cost is relatively cheaper, and then artificially added vitamin A and vitamin D to mimic the composition of cod liver oil. This is not illegal because the international standard for the production of cod liver oil has only one rule – the specific EPA ratio of the final product (EPA to DHA) is in line with the true cod liver oil ratio. However, this practice is not appropriate. 100% natural cod liver oil contains a low concentration of natural, fat-soluble vitamin A, which is suitable for human health. On the contrary, the vitamin A content from artificial cod liver oil is often higher than 5000 IU, which can be really risky for children.
Natural cod liver oil supplementation generally contains an average of 650-1500 IU of vitamin A per serving, which is relatively low compared to the common cod liver oil supplementations on the market ( often contain more than 4500 IU of vitamin A). However, the vitamin A in the synthetic cod liver oil is often too high, which may exceed the proper daily intake recommendation, especially the products for children. The recommended daily nutrient intake (Daily Value, DV) is 5,000 IU for adults, 2,500 IU for children under four years old, and 8,000 IU for pregnant and lactating women. So, go check out the cod liver oil supplementations at hand, see what is the vitamin A content in the supplement facts.