My holiday to Tunisia is booked and because of health issues plus CD I have been given 5Kgs of extra luggage for my foods (classed as medical supplies) this goes in a separate case and goes in the hold. Because of other issues I also get extra leg room and already provided with the seat numbers. I take nibbly bits into the cabin and do not have meals on the flight.
If you are booking a holiday do not be afraid to ask for these extra's,( not all carriers allow it), the more that ask the more awareness to the condition is raised.