Dave Smith wrote:
>
> Is it still chock full of Vitamin C when it has been boiled and reduced
> to a sauce? Vitamins are enzymes, and many other enzymes break down when
> cooked.

Vitamins are not enzymes. Many are cofactors
which assist enzymes, but they are not themselves
enzymes. Vitamin B-12 and folate are heat-labile,
so they do not survive cooking well, but the other
vitamins are heat-stable, or stable enough to survive
cooking without much loss.