It's an interesting question because it informs where we draw arbitrary lines about what's ok to eat and what's not.

Honestly, and not to just be a smart-ass, but what are the acceptable life forms to eat? We've drawn the arbitrary line that "humans aren't ok to eat," but that's really about the only nearly-unanimous thing we can agree upon.

If we move the line further, to say, "no intelligent animals," then we're stuck defining what "intelligent" means, or how complex a nervous system needs to be before we classify it as intelligent.

Ok, we could say "no animals," but why do, say, sponges deserve protection that we don't extend to algae?

Don't get me wrong: I'm fully in favor of re-examining our modern diet and how other living organisms are included in that. It's just an interesting discussion when we move the line further than "no humans".