Also known as retinoic acid
(C1C=CCC(C)(C)C1C=CC(C)=CC=CC(C)=CC=O(O)) it is the organic
part of vision (as 11-cis
retinol). It is also used in the skin. Alledgedly found in carrot
s, as an aid to night vision, its precursor (carotinoids) can be found in most vegetables. Eating too many carrots can make you turn orange :-(
More seriously, polar bear liver contains large amounts of vitamin D (as well as vitamin A) which is why you shouldn't eat (any :) liver (I hate liver). Only fat-soluble vitamins, like A and D (and some Bs) can be overdosed on. C is water soluble, and is simply excreted if taken in too large a quantity.