Food Intolerance - commonly caused by an inability of a person to produce a certain digestive enzyme, which makes them unable to process some foods.
Intolerance to lactose can cause bloating, cramping, diarrhea and excess gas. After eating dairy products people should monitor their reaction to the food to see whether they are intolerant of the food.
Many people are gluten-intloerant. Gluten is a protein found in bread, pasta, cookies, and many other foods containing wheat, barley or rye.