It may come as no surprise that higher crop yields mean lower nutrient values when it comes to the fruits and vegetables we eat. Tom Philpott of Grist reports on this recent University of Texas study [PDF] which showed that mineral content declined by 5% to as much as 40% in some produce. Vitamin and protein content also appear to have slipped.
The principle seems to be that when plants are nudged to produce as much as possible -- whether through lots of synthetic fertilizers and pesticides or through selective breeding -- they deliver fewer nutrients. It evidently isn't just the flavor that's become diluted in those bland supermarket tomatoes.
Although the jury is still out on whether organics offer higher vitamin and mineral content (much depends upon soil quality, conventional or organic), numerous studies have shown organic fruits and vegetables do boast significantly higher antioxidant levels.