Consider the following cases:
- Reuven is deathly ill. He is instructed by doctors to eat pork in order to save his life, so, obviously, he does. But Shimon is a healthy individual and therefore cannot eat pork.
- Shimon is deathly allergic to peanuts, but Reuven has no problem with them.
Can Shimon give the pork or nuts to Reuven? Since Reuven can eat them, is it okay, or since Shimon cannot eat them, is it a problem?
What about the opposite case, where Shimon is able to eat them but Reuven is not?
What if Shimon asks Levi to give the Shaloch Manos? Does Levi have to be able to eat the foods?