I'm looking for a reliable and up to date book on vitamins and minerals to learn more about the stuff I am taking. Can anyone recommend one? Or recommend one not to waste my money on?

I'm particularly interested in something that describes in depth:
- why take that particular supplement
- recommended daily doses
- upper limit, and description of risks in taking too much
- best time to take the supplement
- should supplement be taken in conjunction with another (for example, I know that selenium and vitamin E should be taken together
- descriptions on how the supplement should be processed (like flax seed oil should be cold pressed)

Basically I'm looking for an encyclopedia, but not something too technical like a medical encyclopedia which may be too difficult to understand. There are several listed at amazon.com and chapters.ca, but I have no idea whether they are worth the money.

Thanks in advance.