Twenty years ago, we only knew that vitamins existed. It is exciting, people are now figuring out how vitamins work.
The info on liver is interesting. One big problem, the liver concentrates all of the toxins that industrial farms feed their stock. If someone wants liver, they should get organic grass fed liver. I would not eat liver from industrial farms.
As for my snippy comment. I have a great recipe for turning beta carotene into vitamin A: You start by feeding a carrot to rabbit. You then eat rabbit soup.
RE: Vitamin A — Another Vegan Myth!