Why does eating the same food provoke different physical responses when you have disorders of the gut-brain interaction (DGBI)?

I hear some variation of this story really often. It’s so frustrating because it feels like it’s impossible to stay on top of which foods are really safe. 

Let’s first allow space for this very frustrating situation; it’s not in your head, and it’s not your fault. 

It’s easy for me to say, and much harder for you to feel, but…there aren’t safe or unsafe foods. Short of you having a true allergy or intolerance from an enzyme abnormality, disorders of the gut-brain interaction are not really provoked by a specific food; it’s more about your nervous system finding comfort in a food that you associate with being safe. We are looking to regulate your internal state, not perfectly regulate your environment. DGBI symptoms often respond to your homeostatic state, not the food you ingest.