We did talk about Cod Liver Oil. It is one of my favorite sources of Vitamin A. Unless one is consuming animal liver a couple of times a week, we're not obtaining the retinol form of A.
Under optimal conditions, humans convert carotenes to vitamin A in the upper intestinal tract by the action of bile salts and fat-splitting enzymes. Of the entire family of carotenes, beta-carotene is most easily converted to vitamin A. Early studies indicated an equivalency of 4:1 of beta-carotene to retinol. In other words, four units of beta-carotene were needed to produce one unit of vitamin A. Again, under optimal gut conditions of which, the general public of today is sorely lacking due to antibiotics, chemicals, parasites and other damaging substances.
There are a couple of favorites on the market and Carlsons is one of them.
At 1-2 tbs. daily, this is a fabulous addition to your supplement regimen.
Vitamin A is used in high doses for therapeutic reasons, most namely, cancer.