The Mishna in Kiddushin tells us that a person cannot be mekadesh a women using issurei hana’ah, as these items have no value. The Mishne l’Melech (Ishus perek 5) raises an interesting question: if a person is mekadesh a women who is deathly ill with issurei hana’ah that she needs for her illness, is the kiddushin valid? On the one hand, for this particular woman the issur hana’ah does have value; on the other hand, for the mekadesh and for the rest of the world, the prohibition of using such an item renders it valueless.
Achronim raise a similar question with regards to mishloach manos. If one were to give an item which is assur b’hana’ah to someone who is deathly ill, has one fulfilled the mitzvah of mishloach manos? Does mishloach manos need to be something of value to begin with (and if so, how much value)? Can it have to be something which the recipient alone values, or something of value to the sender as well?
Shu”t L’Horos Nasan (vol 2 # 54) suggests that this question may hinge on a famous dispute between the Terumas haDeshen and the Manos haLevi regarding the purpose of mishloach manos. The TH”D holds that the purpose of mishloach manos is to add to and enhance seudas Purim. Therefore, if a person is deathly ill and is permitted to eat a seudah of issurei hana’ah, these foods can serve as mishloach manos. The Manos haLevi, however, holds that the purpose of mishloach manos is to create a sense of friendship and camaraderie. Support for such an idea can be found in the Ritv”a’s chiddush (Meg 7) that if one gives a mishloach manos of insignificant value to a wealthy important person, one has not fulfilled the mitzvah. Since the gift makes no impression on the recipient and does not foster any feeling of friendship, it cannot count as mishloach manos. Perhaps one can apply the same chiddush in reverse to our case. Since giving away issurei hana’ah costs nothing and is something the giver would want to get rid of anyway, it does not convey that feeling of friendship that mishloach manos is supposed to foster and would therefore not fulfill the mitzvah.