Food is complex. Some of the natural chemicals that contribute flavour to fresh foods are the salicylates, amines and glutamates. Manufacturers add preservatives, colouring and flavouring chemicals to food to enhance looks, taste and shelf life.
Both FODMAP and food chemical triggers can impact gut symptoms, but food chemicals can also influence headaches, migraines, sleep, mood, brain fog, skin itch and rashes, to name some. Like FODMAPs an elimination diet and challenge protocol can be followed, or some just dabble with limiting foods categorized in the very high list.