A report in this month's issue of the Journal of Horticultural Science (I've already read my copy!) explains how today's veggies and fruits may be as much as 40% lower in minerals than the same produce from 50 years ago. Why?
One big reason is selective breeding that selects for bigger, prettier fruit that generally has higher concentrations of "dry matter" without a similar increase in nutrient content. But that's not all.
This article appears in Feb 18-24, 2009.