Douglas Wilson has a really nice post on the topic of "all natural" food. Fun and witty. In fact, I have found his recent writings on the topic of Creation & Food to be very, very insightful and edifying reading.
Food faddism has been a hot topic in the Church at least since Paul wrote to the Colossians, and it is making the rounds again these days. It coincides, of course, with the rise of the "green" movement, whose anti-industrialism makes necessary the glorification of the agrarian life. Wilson's essays have had a steady hand on the question of what God thinks of food, and I therefore commend them all to you.