Here is a video from YouTube about nutrition in our plant stocks. I read this articles many years ago and could not find it to print out as it is excellent. Shame they did not mention the 2004(ish) study to companion this. Though it is a GREAT watch and may explain a few things about our food. Though it does not go into forced growing speeds and nutrition depletion as I would have liked it would have. Once I find that study, again, I will link it.
(HERE IT IS, in a brief form)Changes in USDA food composition data for 43 garden crops, 1950 to 1999.
Mineral nutrient composition of vegetables, fruits and grains: The context of reports of apparent historical declines
Are Depleted Soils Causing a Reduction in the Mineral Content Of Food Crops?
The great nutrient collapse
Researchers find rice grown in high carbon dioxide environments may be less nutritious