The best way to identify a possible food sensitivity or intolerance is through the use of an elimination diet. This is not a "diet" in the traditional sense, but a way to systematically find out if certain foods are causing symptoms in your body.
Time Required: Minutes per day
Make an appointment with your physician to rule out an intolerance to lactose or gluten. Don't skip this step! It's importance is more fully explained in this article: "Before You Go Gluten Free for IBS".
Start an elimination diet. Eliminate any suspect foods for a period of two weeks. Many people start by eliminating all dairy, gluten and soy products.
At the end of the two weeks, slowly re-introduce one food group at a time back into your diet. Pick one food group and eat foods containing that item on the first day. Don't eat the food for the next two days, but look for symptoms. If you experience symptoms, then you have identified a food trigger. If your symptoms do not return, you can consider that food group to be non-reactive for you.
- Once you have a clear sense of whether one particular food group is a trigger for you, you are ready to repeat the three day process with the next food group.
Heizer, W., Southern, S. & McGovern, S. "The Role of Diet in Symptoms of Irritable Bowel Syndrome in Adults: A Narrative Review" The Journal of the American Dietetic Association 2009 109:1204-1214.