A recent post referenced a Feb 2009 article by Donald R Davis in the HortScience journal. While this is pretty much a literature review - the topic is interesting.
Here's a quick take:
- High yield cultivars (veg varieties) tend to have lower nutrient levels than lower yield cultivars.
- Average nutrient levels in fruit/veg in the US/UK has declined since the 1940's
- Application of fertilizer/chemicals increase the content of those elements while reducing other nutrients in vegetables.
First blush? I'm not surprised. In fact, these results make perfect sense to me. Want to know why? (that's called a "tease")