Is there anything in particular you feel you might be intolerant to? For example Dairy?Wheat?
The most reliable way to determine this is through following an elimination diet and cutting the food out completely for a few weeks then introducing a small amount of it. I have ulcerative colitis and my gastro specialist along with a dietician both insisted it was the best method to determine which foods I was intolerant to and triggered my flare ups.
If however you are getting allergic reactions such as mouth or face swellings, hives or severe vomiting with certain foods then I'd see your GP for a referral where the hospital can do a rast test (pin prick with various allergens that may produce wheals) or the food challenge test where small amounts of potential allergen are given to you to ingest in a controlled environment with medication on hand)
Hope this helps?