Wendell Berry famously said "eating is inescapably an agricultural act [...] how we eat determines how the world is used."
It is one of my favourite quotations. It captures a few concepts worth keeping in mind.
1. That producing food necessarily requires using natural resources (like soil and water) and natural habitats of other animals and creatures. This is (currently) an inescapable fact. Everything you eat, and most clothes you wear, come from raw ingredients grown in a place. And therefore how they are produced has an impact on that place - the health of that field, farm, river, lake or sea.
2. In today's age this link is often international, distanced and obscured. Whether that's by intermediary companies like supermarkets labelling meat that actually comes from abroad with fake UK farm names to deliberately obscure and mislead, or by processing; some foods don't come from one place but are made of ingredients that come from all over the world (think high-fructose corn syrup).
3. Often, the more obscured the link, the harder it is to know the impact of our choices. We can't walk onto the farm, visit the workers, see the wildlife. And the more obscured the less we know about and can control other conditions such as food hygiene, worker conditions and animal welfare.
Wendell Berry's words can be paraphrased by borrowing from the 17th century french philosopher, Descartes, into "I eat therefore I farm". The choices you make about my food determine what farms and farming methods you are supporting, and which you are not supporting, even though you may no longer be doing the farming yourself.
When people argue against the merits of local food systems, they are too quick to overlook the inescapable fact that they themselves are farmers so long as they keep eating. And it's easier to determine how their local farm is used, compared to a farm they don't know on another continent under regulations they can't control.