Back in the 70's when the airlines offered "No Frills" flights, you could bring your own food on board and even have the F/A heat it up for you. The very next summer there were lots of outbreaks of food poisionings on airplanes. What was happening was that people were bringing their own food on board from home and they weren't taking proper care of it and in the summer heat the food was spoiling due to lack of refrigeration. And if the F/A complied and heated the food this usually accelerated the growth of toxic bacteria. My sister was a F/A with TW at the time and she remembers the memo that came out instructing all F/A's to immediately stop heating up food that was not airline supplied. Shortly thereafter the food poisionings stopped.
Fly North Central Airlines..The route of the Northliners!