How can we build supply chains sustainable food?

First edition of the "Eating Cities", which takes place every two years in a different city to better understand the issue of food supply in major cities according to different views and situations.
Ecomeal.info portal devoted to social dialogue on food service lets you share and create networks between all participants before and after the event "Eating Cities".
The city eats. Not only food, but also all the land necessary to produce these foods. The flow towards large cities do not relax, it becomes intense and of course inevitable. Sustainability encompasses all aspects from production, processing, distribution and logistics. The problem arises not only in terms of quantity of food required, but also in terms of impacts generated such as emissions of greenhouse gas emissions.

We get the food, made thousands of miles away. Give more value to local production means certainly reduce GHG emissions and promote the local economy, but in the other hand it will limit our choices and our knowledge of other food crops. What is better, kilometer zero and / or a variety of products?