A quick fact for you to consider. Cod liver oil used to have a lot of vitamin D in it. Now it does not because cod liver oil is obtained from farm fish which are not fed naturally and that fish food is low in vitamin D.
So, again take advice from the people who know. I am one of those because I read the experts at vitamin D council and grass roots health. I have read everything I can find on this subject for a dozen years. Evidently Doctor Oz has not!
I will quote a very old philosopher. Plato said, know thy self. Very true, but also know your Doctor. Many do not stay current with the latest information.