How Do Diet and Stress Affect IBS?

The potential for abnormal function of the colon is always present in people with IBS, but a trigger also must be present to cause symptoms. The most likely culprits seem to be diet and emotional stress. Many people report that their symptoms occur following a meal or when they are under stress. No one is sure why this happens, but scientists have some clues.

Eating causes contractions of the colon. Normally, this response may cause an urge to have a bowel movement within 30 to 60 minutes after a meal. In people with IBS, the urge may come sooner with cramps and diarrhea.

The strength of the response is often related to the number of calories in a meal and especially the amount of fat in a meal. Fat in any form (animal or vegetable) is a strong stimulus of colonic contractions after a meal. Many foods contain fat, especially meats of all kinds, poultry skin, whole milk, cream, cheese, butter, vegetable oil, margarine, shortening, avocados, and whipped toppings.

Stress also stimulates colonic spasm in people with IBS. This process is not completely understood, but scientists point out that the colon is controlled partly by the nervous system. Stress reduction (relaxation) training or counseling and support help relieve IBS symptoms in some people. However, doctors are quick to note that this does not mean IBS is the result of a personality disorder. IBS is at least partly a disorder of colon motility.