Berry's comments from the Art of the Commonplace, are helpful in describing the benefits of growing your own vegetables and knowing the origins of the meat we eat.
The pleasure of eating should be an extensive pleasure, not that of the mere gourmet. People who know the garden in which their vegetables have grown and known that the garden is healthy will remember the beauty of the growing plants, perhaps in the dewy first light of morning when gardens are at their best. Such a memory involves itself with the food and is one of the pleasures of eating. The knowledge of good health of the garden relieves and frees and comforts the eater.
The same goes for eating meat. The thought of the good pasture and of the calf contentedly grazing flavors the steak. Some, I know, will think this bloodthirsty or worse to eat a fellow creature you have known all its life. On the contrary, I think it means that you eat with understanding and with gratitude. A significant part of the pleasure of eating is in one's accurate consciousness of the lives and the world from which food comes.
I hear people getting into debates about whether organic vegetables are, from the perspective of chemistry, more nutritious. Others debate the financial advantage of growing your own vegetables. Some take a pragmatic view of the politics and say things like, "the corporate agriculture industry would like nothing better than to see us spend all of our free time in our gardens and not in political dissent." And of course we love to debate the mathematics of carbon footprints.
While these perspectives are all important and need to be debated and discussed, none are quite as compelling to me as the one Berry makes in the quote above. Instead of breaking things down to their component parts, which is what our scientific approaches do, Berry is putting the food we eat in context, using words like beauty, memory and contentment. He says that simply knowing the source and conditions of the land and animals that provide our food makes the food taste better (and I would add, in many cases worse.) I can't prove it with a scientific study but I know it to be true from my experience.