timmyb wrote: Does cod liver oil have too much Vitamin A? What is the best fish oil?
NOTE: Nowhere is there written a standard definition of what exactly constitutes cod liver oil. This simply means that the manufacturers are free to add any amount of vitamin A and/or D that they see fit. In other words, our government does not have an official guideline when it comes to manufacturing cod liver oil, and extra vitamin A and/or vitamin D are normally added in some amount.
Vitamin A and vitamin D depend on each other in order to accomplish what they’re meant to. This means that without vitamin D, vitamin A can be completely ineffective and even toxic. And if you’re deficient in vitamin A, then vitamin D can’t function properly either.
Keep the above information in mind as you read the following research; in 2008, Dr. John Cannell, who is head of the U.S. Vitamin D Council, and 15 other researchers released a study in which the doctors claimed that cod liver oil can actually cause a vitamin A deficiency and even toxicity. Weird, right? But by remembering the first paragraph, you’ll understand how this can happen.
The reason that taking cod liver oil isn’t guaranteed safe is that the vitamin A in cod liver oil is extremely variable and in fact often excessive, and cod liver oil contains far less vitamin D than vitamin A. And as explained in the first paragraph, too much vitamin A and not enough vitamin D can cause vitamin A toxicity. In the study released, it was stated that the various samples of cod liver oil that were taken showed that many brands contained as much as 12,000 times more vitamin A than vitamin D.
These facts about cod liver oil DO NOT apply to regular fish oil or krill oil because these do not contain vitamins A or D, but are excellent sources of the essential omega-3 fats.