I have been intrigued by the idea of a 50-mile diet ever since the first reference I heard to it a few years ago. For me, the concept wasn't really about the 50-mile delineation, but rather about choosing foods that were being grown from closer to home by people whom I could personally identify with.
A few years ago I worked in northern Ghana with a development organization that was engaged in agricultural development. I became familiar with an incredibly interesting social marketing project that one of my mentors was running, albeit I was not directly involved in it. The project was essentially an 'eat local' campaign for Ghana rice. (I highly recommend that readers check out the story behind the campaign, if only to listen to the great radio jingle that went viral in Ghana!).
The context of that campaign is a little startling. Although Ghana can produce its own rice, most rice is imported from places like the U.S. and Thailand. The imported rice is significantly cheaper than the rice being produced domestically. The reason? The exporting countries have large subsidy programs that keep their rice markets alive and well at home and dump super cheap rice on foreign markets. In Ghana that 'dumping' is impeding the development of fair business that could sustain a stronger rice farming economy on their own soil. It is a vicious cycle of impeding progress in the pursuit of a bargain, and its impact is most consequential to the poor.
It is ironic that it is cheaper for a poor rice farmer in Ghana (who might make $400/year in total income) to buy imported rice to feed his family than it is to eat his own rice. It is more disconcerting that a country like Canada we face the same situation. In order to survive, the concept of 'Local Food' has had to occupy a narrow piece of food real-estate by branding itself as a premium product with a premium price. The issue is that most of our local food producers are in the same position as those Ghanaian farmers, working madly to sell their local goods, but achieving a margin that leaves them in lower stratospheres of the economy (granted, Canada's low-income demographic is much richer than that of Ghana).
There is a common thread of local food promotion that insinuates that we should buy local so that we can 'do what is right.' While I think that this is a decent social motivator for some people, it does not necessarily change people's behaviour in the long term. The impact in Ghana appeared to be diffused as time when on and the campaign ended.
Nevertheless, people have a broad range of motivators when they shop that go beyond the monetary transaction. The most apparent motivator in the North American shop local movement is the positive social transaction that happens when they spend money on something they can connect to a person. Ie. We want to relate to the people we buy from.
How often do we pick up a product in a grocery store and think 'Hey, I know who made this' ? It's not an easy connection to make, but to me it seems to be a strong indicator for where we can improve how we shop in grocery stores. There are already a certain number of locally-made and regionally-made products in grocery stores (here in Alberta we know that even major chains will stock between 100 - 400 products that meet our strict definitions for regional food, production, and ownership). We just need to start show-casing them and creating ways to connect shoppers to the makers. Interestingly, a lot of these products are not branded as premium local products - however they nevertheless have positive social and economic impacts on the communities in which they are produced.
There are a lot of limitations to getting local food into grocery stores, but there really shouldn't be limitations to promoting that food. (And that includes taking the premise of the 50-mile diet and infusing it with more than just miles). We've gotta start experimenting in this arena, and make sure that when we talk about supporting local, we are encompassing the broadest definition of support possible - right from the farmers' market stall to the grocery store aisles.