Because I realize that the words "intolerance" and "allergy" are often used interchangeably when it comes to food (though technically they are different, I am told), my question applies to either situation. In other words what food(s) definitely cause your body to react in a way that can be considered negative or undesirable?
My major problem food is anything in the allium family (garlic, onion, shallots, leeks, chives); even a small amount will trigger an adverse stomach reaction for hours -- so I avoid all those like the plague. Onions/shallots etc were always an issue even as a child but it got worse with age; garlic was fine until age 35 at which point it suddenly became pure poison! (just one too many orders of Caesar salad, maybe)
Wine or any other alcoholic drink will bring on a killer sinus headache in minutes (obviously that was discovered in adulthood, LOL!). No idea what the culprit is so I just completely avoid.
Kiwi, cantaloupe, honeydew, and raw banana (although cooked bananas, as in pies, breads and muffins are fine; go figure) all cause a moderate reaction (itching) so I avoid those as well. Kiwi is definitely the worst of that bunch, reactionwise; good thing it's not a favorite but it appears in a lot of mixed fruit salads in restaurant settings.
What foods are Bad Guys for you?