It is essential that everybody knows the nutrition basics. There are many excellent websites and books that can provide you with grade A information, and here I have gathered together the best sites and books for just that.
Now you might wonder why I have chosen so many government websites. This is because they are reliable, and written and edited by health experts that have been working in the field for a long time and based on science. While a wide array of diet-sites and blogs can provide nutritional information, you won’t know whether the information is accurate or where the writers have found this information. Very likely he or she has found the information from other websites of questionable trustworthiness.
Like with this site, make sure that everything is referenced, and that the origin is trustworthy.

Basic on nutrition:
Centers for Disease Control and Prevention :
Water
Dietary fat:
–>Trans Fat
–>Saturated Fat
–>Cholesterol
–>Polyunsaturated Fats and Monounsaturated Fats
Protein
Carbohydrates

Vitamins and minerals
Office of dietary supplements 
Calcium
Chromium
Folate
Iron
Magnesium
Selenium
Vitamin A
Vitamin B6
Vitamin B12
Vitamin D
Vitamin E
Vitamin K: Interactions with Coumadin (PDF-39k)
Zinc

Sports nutrition:
Australian institute of sports -> information on what to eat for your sport.
Easy to read, detailed and informative