First: the New York Times has published the article you've been looking for to refute the racists who insist on differences in IQ due to race, rather than environmental factors while growing up, to wit: "[T]he psychologist Elsie Moore ... looked at black and mixed-race children adopted by middle-class families, either black or white, and found no difference in I.Q. between the black and mixed-race children. Most telling is Dr. Moore’s finding that children adopted by white families had I.Q.’s 13 points higher than those of children adopted by black families. The environments that even middle-class black children grow up in are not as favorable for the development of I.Q. as those of middle-class whites."
The challenge, as I see it, is to figure out how to even up those environments. And for some good basic data to challenge any academic hiding his racism under his robes, there's always Stephen Gould's The Mismeasure of Man.
Second: fresh and local does not mean greener. Do you 1) drive to the grocery store 2) eat meat (sorry, I know I do) and 3) throw away a lot of food? Then you're contributing to the problem. And food transported in bulk (by shipping container) may be greener than anything that gets to you in a small truck.