It's my people's biological makeup. It's of opposite chirality to humans. [Would a demon from several hundred human years ago have any idea what chemical chirality is? The questions she has to ask herself these days... Just in case, she keeps going:] It's like trying to put your left glove on the right hand. They're oriented the wrong way - same with our biology.

So if a quarian or a turian - like Garrus - ate human food, we might be fine. It wouldn't have any nutrition we could use, but we'd be fine. Or he might have a major allergic reaction and die, I don't know.

[She quirks her head, grinning ironically.] But quarians don't have immune systems that work, so we're not allergic... although if we kept eating it, we might get allergic. [She makes a vague sort of gesture.] It's just not a good idea.

[Biology is dumb. Who would have thought.]