Constipation is defined as having a bowel movement fewer than three times per week. With constipation stools are usually hard, dry, small in size, and difficult to eliminate. Some people who are constipated find it painful to have a bowel movement and often experience straining, bloating, and the sensation of a full bowel.
Some people think they are constipated if they do not have a bowel movement every day. However, normal stool elimination may be three times a day or three times a week, depending on the person.
Constipation is a symptom, not a disease. Almost everyone experiences constipation at some point in their life, and a poor diet typically is the cause. Most constipation is temporary and not serious. Understanding its causes, prevention, and treatment will help most people find relief.
Who gets constipated?
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. Those reporting constipation most often are women and adults ages 65 and older. Pregnant women may have constipation, and it is a common problem following childbirth or surgery.
Self-treatment of constipation with over-the-counter (OTC) laxatives is by far the most common aid. Around $725 million is spent on laxative products each year in America.
What causes constipation?
To understand constipation, it helps to know how the colon, or large intestine, works. As food moves through the colon, the colon absorbs water from the food while it forms waste products, or 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. Common causes of constipation are
- not enough fiber in the diet
- lack of physical activity (especially in the elderly)
- irritable bowel syndrome
- changes in life or routine such as pregnancy, aging, and travel
- abuse of laxatives
- ignoring the urge to have a bowel movement
- specific diseases or conditions, such as stroke (most common)
- problems with the colon and rectum
- problems with intestinal function (chronic idiopathic constipation)
Not Enough Fiber in the Diet
People who eat a high-fiber diet are less likely to become constipated. The most common causes of constipation are a diet low in fiber or a diet high in fats, such as cheese, eggs, and meats.
Fiber—both soluble and insoluble—is the part of fruits, vegetables, and grains that the body cannot digest. Soluble fiber dissolves easily in water and takes on a soft, gel-like texture in the intestines. Insoluble fiber passes through the intestines almost unchanged. The bulk and soft texture of fiber help prevent hard, dry stools that are difficult to pass.
Americans eat an average of 5 to 14 grams of fiber daily,* which is short of the 20 to 35 grams recommended by the American Dietetic Association. Both children and adults often eat too many refined and processed foods from which the natural fiber has been removed.
A low-fiber diet also plays a key role in constipation among older adults, who may lose interest in eating and choose foods that are quick to make or buy, such as fast foods, or prepared foods, both of which are usually low in fiber. Also, difficulties with chewing or swallowing may cause older people to eat soft foods that are processed and low in fiber.
Not Enough Liquids
Research shows that although increased fluid intake does not necessarily help relieve constipation, many people report some relief from their constipation if they drink fluids such as water and juice and avoid dehydration. Liquids add fluid to the colon and bulk to stools, making bowel movements softer and easier to pass. People who have problems with constipation should try to drink liquids every day. However, liquids that contain caffeine, such as coffee and cola drinks will worsen one's symptoms by causing dehydration. Alcohol is another beverage that causes dehydration. It is important to drink fluids that hydrate the body, especially when consuming caffeine containing drinks or alcoholic beverages.
Lack of Physical Activity
A lack of physical activity can lead to constipation, although doctors do not know precisely why. For example, constipation often occurs after an accident or during an illness when one must stay in bed and cannot exercise. Lack of physical activity is thought to be one of the reasons constipation is common in older people.
Some medications can cause constipation, including
- pain medications (especially narcotics)
- antacids that contain aluminum and calcium
- blood pressure medications (calcium channel blockers)
- antiparkinson drugs
- iron supplements
Changes in Life or Routine
During pregnancy, women may be constipated because of hormonal changes or because the uterus compresses the intestine. Aging may also affect bowel regularity, because a slower metabolism results in less intestinal activity and muscle tone. In addition, people often become constipated when traveling, because their normal diet and daily routine are disrupted.
Abuse of Laxatives
The common belief that people must have a daily bowel movement has led to self-medicating with OTC laxative products. Although people may feel relief when they use laxatives, typically they must increase the dose over time because the body grows reliant on laxatives in order to have a bowel movement. As a result, laxatives may become habit-forming.
Ignoring the Urge to Have a Bowel Movement
People who ignore the urge to have a bowel movement may eventually stop feeling the need to have one, which can lead to constipation. Some people delay having a bowel movement because they do not want to use toilets outside the home. Others ignore the urge because of emotional stress or because they are too busy. Children may postpone having a bowel movement because of stressful toilet training or because they do not want to interrupt their play.
Diseases that cause constipation include neurological disorders, metabolic and endocrine disorders, and systemic conditions that affect organ systems. These disorders can slow the movement of stool through the colon, rectum, or anus.
Conditions that can cause constipation are found below.
- multiple sclerosis
- Parkinson's disease
- chronic idiopathic intestinal pseudo-obstruction
- spinal cord injuries
Metabolic and endocrine conditions
- poor glycemic control
Problems with the Colon and Rectum
Intestinal obstruction, scar tissue—also called adhesions—diverticulosis, tumors, colorectal stricture, Hirschsprung disease, or cancer can compress, squeeze, or narrow the intestine and rectum and cause constipation.
Problems with Intestinal Function
The two types of constipation are idiopathic constipation and functional constipation. Irritable bowel syndrome (IBS) with predominant symptoms of constipation is categorized separately.
Idiopathic—of unknown origin—constipation does not respond to standard treatment.
Functional constipation means that the bowel is healthy but not working properly. Functional constipation is often the result of poor dietary habits and lifestyle. It occurs in both children and adults and is most common in women. Colonic inertia, delayed transit, and pelvic floor dysfunction are three types of functional constipation. Colonic inertia and delayed transit are caused by a decrease in muscle activity in the colon. These syndromes may affect the entire colon or may be confined to the lower, or sigmoid, colon.
Pelvic floor dysfunction is caused by a weakness of the muscles in the pelvis surrounding the anus and rectum. However, because this group of muscles is voluntarily controlled to some extent, biofeedback training is somewhat successful in retraining the muscles to function normally and improving the ability to have a bowel movement.
Functional constipation that stems from problems in the structure of the anus and rectum is known as anorectal dysfunction, or anismus. These abnormalities result in an inability to relax the rectal and anal muscles that allow stool to exit.
People with IBS having predominantly constipation also have pain and bloating as part of their symptoms.
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