"Problem foods" refers to specific types of food that can cause issues or difficulties for certain individuals due to allergies, sensitivities, or other health-related concerns. Full definition
My diet is becoming very limited as I'm now just eating meat, eggs and roast potatoes in order to eliminate problem foods. (supernaturalacnetreatment.com)
Depending on the type of food intolerance you have, you may be able to eat small amounts of problem foods without a reaction. (mayoclinic.org)
Keep a diet journal if you find that helpful for identifying problem foods. (mindbodygreen.com)