The larger issue is that consumers have no way of assessing the nutritional value of the items they're purchasing at the point of purchase. Cost is mediated on the basis of weight, which results in water-rich, nutrient poor, taste-poor produce. Saline injection into meat is another similar issue.
How do we make growing nutritional food profitable? Foods that can be sold on the basis of nutrient specific benefits, like Golden Rice or Vitamn D enriched milk can be marketed and sold on that basis, but comparing two beefsteak tomatoes grown in differing soils is not possible at present at the point of sale.
Typical food certification strategies, such as Organic, DOP, AOC, and other regional growth indicators don't seem to fit the bill. It's also unclear whether or not there is a market for inspections on the basis of nutritional value - from an organizational standpoint, it shouldn't be too difficult to have an inspector randomly audit crops and send samples to a lab to be HPLC or Mass Spec'd, but whether or not another certification mark changes buying patterns is unclear.