I knew of plenty of CO's that had specific dietry requirements, and none of them where medically sound.
We had one guy that could not eat bread, another who could not eat food cooked in various different oils, also most had the usual dairy complaints, but they loved their icecream!
The funniest and hypocritical one I heard was one who couldn't eat red meat due to producing excessive iron in his blood, but he loved eating nuts and mushrooms (which contain high amounts of iron in them).
I remember one sister was told by the CO's wife that they would not be eating at her place as they were going some other place straight after the morning witnessing group, but they would like their lunch meal packed for them so that they could take it with them. This was told to her at the service group that very day. I know what I would have said to her!