I forgot to add that you can find a lot of incredibly useful material at
www.nap.edu with
Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients) (aka
The Macronutrient Report) being an invaluable reference for anyone with a serious interest in nutrition. The Linus Pauling Institute's Micronutrient Information Center (
link) is another useful resource.