It may be of interest to some: As food costs have come down in US so have some important nutrients in fruit & veggies.

Eating Your Veggies: Not As Good For You? http://www.time.com/time/health/article/0,8599,1880145,00.ht...

And,

Changes in USDA Food Composition Data for 43 Garden Crops, 1950 to 1999 http://www.jacn.org/content/23/6/669.full

Which concludes: "We suggest that any real declines are generally most easily explained by changes in cultivated varieties between 1950 and 1999, in which there may be trade-offs between yield and nutrient content."