I'm vegan. I heard a talk by a very well educated man who's spent his adult life studying this stuff and he said that even accounting for air miles, most of the time, vegan is always a better option for the environment. Obviously chickens in your own bac yard is a bit different, but when talking about cheese for example, he said vegan cheese, even with coconut oil is less carbon intensive than cow's milk cheese, despite the air miles. But of course, you're right about the palm oil and it's always worth weighing up each thing we buy individually. It's so hard to avoid palm oil. It'd be nice if stuff had carbon labelling, but then I suspect that would be open to abuse.