Even when we try to eat the right foods, they no longer have the nutritional value that they once did.
For instance, cabbage that was grown in New Mexico was tested for it's Vitamin C content. Cabbage is supposed to be the greatest source of Vitamin C of any food, apart from citrus fruits. The conclusion of the test was that there was no measurable Vitamin C found in this cabbage.
In Pennsylvania, carrots grown there were tested for their nutritional value. The normal score for nutritional content is 22. These carrots tested at 6. They looked orange and healthy. But this food that is supposed to be filled with nutrition was shown to be seriously missing it's nutritional value.
So much of our soil today is mineral deficient. Vitamins without minerals are useless to the human body, because they both work together. Foods that are mineral deficient lead to disease.
For more information, see Senate Document No. 264.