[Xantar]

Well, in a way we do eat people. You see, when people die, we either bury them or cremate them (or dump them into the sea). In any case, the body decomposes and eventually becomes a part of the soil or sea. And plants use those decomposed bodies to form their own bodies.

So, the chances are in fact very good that some of the atoms you have eaten were part of a human being at one point. But then again, some of the atoms that make up your own body used to be part of a plant.