[Well, that's a rather unpleasant thing to tell a little girl, but Konan isn't one to shy from harsh truths. Instead, she gives a slightly toned down one.]

There are some people in my world who are experts in poisons and drugs that will try to use them against their enemies for an easy victory. So if you don't trust what the person is trying to feed you, that's one way of testing if there actually is something wrong with it.