Constipation is one of the most common gastrointestinal complaints in the United States. More than 4 million Americans have frequent constipation, accounting for 2.5 million physician visits a year.  But what is constipation and how can we realistically define a healthy frequency of bowel movements?

What is constipation?
Constipation is the infrequent and difficult passage of stool, or waste products, from the body. The frequency of bowel movements among healthy people varies greatly, ranging from three movements a day to three a week. However, since more than 98% of people have at least 3 bowel movements per week, less is often viewed as abnormal.

To understand constipation, it helps to know how the colon, or large intestine, works. As food moves through the colon, the colon absorbs water while it forms stool. Muscle contractions in the colon then push the stool toward the rectum. By the time stool reaches the rectum it is solid, because most of the water has been absorbed.

Constipation occurs when the colon absorbs too much water or if the colon's muscle contractions are slow or sluggish, causing the stool to move through the colon too slowly. As a result, stools can become hard and dry.