Jon brings a good point. The foods that a in the stores today are not the same as they were 100 years ago. Most foods you buy are not foods at all they are food products. The nutrients are stripped during the processing of foods and then fortified at a later point. That is why whole food supplementation is essential today.
I could write a book on the difference between whole food supplements and "GNC" garbage that is sold. Most of the stuff that is sold on the market today are only fragment of the original vitamin. Look at the picture below, that is a chromatogram of whole food vitamin c versus a synthetic ascorbic acid. As you can see the ascorbic acid is missing some things. The missing components are called micronutrients and are only found in nature, they cannot be synthesized in a lab. The missing micro nutrients are the major factor in making the rest of the complex work biochemically. This is why I said most of the stuff you guys are buying is junk. Sorry if you got your butts hurt, but save your money. If you are seeing good results it is not from your muscle milk or the protein concoction you brew up in your blender, it is from your hard work.
http://www.integratedholisticsolutions.com/images/vit-C_chromatogram.jpg