Hi Lolly,
Thanks for the question.
It is important to differentiate between Cod Liver and fish oil.
Cod liver I presume is mainly from the liver and contains A and D.
Fish oil is from the body of other species and is not listed as containing A and D.
Some products mix the two so check the label.
Beyond a few basic searches and ensuring I use a mix of cod liver oil and fish oil, or a product that mixes the two, on the grounds that Eskimos and fisherman seem to manage quite well, for moderate consumption [eg not more than 3tps a day] of cod liver, and maybe the some fish oil as well I took a view that I was probably in fairly safe territory.
As usual life is rarely simple and there are always exceptions so please advise your doctor you are taking cod liver / fish oil and discuss the matter with your medical adviser.
Here is a link to an informative site that from my previous experience contains considered and researched information. As usual there is debate among the experts on the optimal dosages. There is more interesting material on vitamin A dosages sources etc at this link;
http://www.westonaprice.org/basicnut...fications.html
Abstract
"
Vitamin D
The recommended dosages for cod liver oil provide about 500 IU vitamin D for children, 1000 IU vitamin D for adults, 2000 IU vitamin D for pregnant and nursing women and up to 9000 IU for those taking large amounts of cod liver oil to deal with stress and disease.
In 1997, the Food and Nutrition Board of the US Institute of Medicine set the tolerable upper intake level (TUIL) for vitamin D at 2000 IU per day. However, the vitamin D content experts on the Upper Limits Panel objected to this limit, and several prominent vitamin D researchers have called for an upward revision of the limit. Experiments show that even during the winter with a low vitamin D intake, humans will exhaust stores of vitamin D at a rate of 3000-4000 IU per day, an amount that many people require to maintain optimal levels of the vitamin in the blood. Extensive exposure to summer sun at mid latitudes naturally produces levels of vitamin D in the blood equivalent to what is attained by supplementing with a continued daily dose of 10,000 IU, suggesting humans are designed to tolerate such large amounts of vitamin D.(4)
If you are a lifeguard or spend a lot of time in the sun, you do not need to take supplemental vitamin D; however you still need to consume adequate vitamin A. Animal studies show that even moderate amounts of vitamin D increase the body's need for vitamin A, whether the vitamin D is provided in the diet or by UV light (2,5). So, if you cut back or eliminate cod liver oil in the summer, be sure to consume plenty of oily fish, liver, butterfat and egg yolks from grass-fed hens to ensure adequate vitamin A.
For a discussion of Vitamin D Toxicity, see
http://www.cholecalciferol-council.com/toxicity.pdf
This does not mean we do not recommend that some individuals have their vitamin D levels tested. Such testing can be very useful in determining vitamin D status and the effectiveness of cod liver oil or vitamin D supplements.
Cod Liver Oil"
Links for Cod Liver Oil and Fish Oil - note one has A and D and the other does not.
http://www.vitacost.com/Carlson-Norw...igh-In-EPA-DHA
http://www.vitacost.com/Carlson-The-...inest-Fish-Oil