A new dilemma for omnivores.

That headline is part of a proverb or axiom: "One person's meat is another's poison." (When it was coined, it was "One man's meat," but we've amended in the interests of not being sexist.)

It was to do with the impact that raising meat has on the planet -- specifically, the climate.  Raising and eating meat contribute a lot to global warming -- more than SUVs, for example. A couple of ad campaigns address the issue.