Common Sources of Food Intolerance 

Common triggers among both allergies and food intolerances are nuts, fish, dairy products, eggs, soy and wheat. Syrup, corn and fruit sugar (fructose) also can be problematic. Fructose intolerance and lactose intolerance are among the most prevalent and the easiest to diagnose. Avoiding these foods is one way to minimize the painful symptoms associated with the condition. 

With 7 to 20 percent of adults experiencing symptoms like irritable bowel syndrome, researchers in the March 2011 issue of Gastroenterology Clinics of North America noted that many people with IBS report symptoms shortly after eating. They report that as many as 93 percent of patients fell ill within three hours of eating, citing another study. The study found that people who experience food intolerance symptoms often receive the wrong treatment when what they really need is dietary intervention and counseling. 

The best way to identify the problem is to journal about your diet and reactions after eating certain foods. By tracking how you feel, you may be able to see a pattern and learn which foods cause you trouble. When that food is removed from your diet completely, you should feel better and lose the symptoms associated with food intolerance.