@MaterS Good point, some are that sensitive, and yes, my S has asked people if they could hold off on eating their peanuts. He has also asked the flight attendant for help in swapping seats when his neighbor could not postpone his peanut consumption.
@jazzymomof7 What snacks he takes is a function of where he is going. Last week he flew San Francisco to Dallas to Washington Dulles (a full day of flying). The connection in Dallas was tight so picking up food there was not an option. Additionally, his arrival time in Washington was 1 AM, so food options then were problematic. He ate at SFO just before his first flight, and he took a few of his regular snacks: Pop Tarts, Goldfish, and Doritos. BTW, he always (always, always, always) reads the complete ingredient list even on snacks he has used in the past as ingredients sometimes change and what was once safe is no longer safe). On longer (vacation) flights we have taken much more: fresh fruit, cheeses, dried salami, etc. Some of the food can not be imported into your destination, but some can. Check import rules.