The couple in the city recommended me the movie: Food, Inc. by Robert Kenner
I watched it in the morning and it is more like a documentary about the food industry, especially farming in the US. If you have time, you should definitely watch it. We should know and be aware of what we eat and how it is produced.
I found this web page and here is some advice how to change your habits relating to nutrition
Very interesting as well:
An inconvenient truth by Davis Guggenheim