by James M Stewart, MD
The gastrointestinal tract is designed to break apart food so that we absorb the nutrients we need while leaving behind the material in food we don’t need. To do this, our body secretes digestive enzymes from the pancreas and water from the body to liquefy the food we eat so that it can mix around in the intestines. Once the nutrients are absorbed, the remaining liquid with the non-absorbed food material enters the large intestine.
The role of the large intestine is to remove as much of the remaining liquid that was added to the food so that we don’t waste water. It is a very slow process and usually takes about 24 hours. Through very slow movements, the liquid waste is slowly turned into solid waste until enough has accumulated. At this point, most of us will feel the need to have a bowel movement and push the solid waste out of the body.
Constipation is when that process takes too long or there is something not functioning correctly with the muscles that coordinate bowel movements. When one meets with a physician, it is important to be very clear what one means by constipation because there are multiple symptoms that are called constipation. Constipation can mean that you have very infrequent bowel movements (less than 3 per week) or that it can very difficult to pass stool (straining while having a bowel movement). For the purposes of this article we will discuss infrequent bowel movements.
Most constipation in the United States is related to slow movement through the large intestine which results in infrequent bowel movements or hard bowel movements. There are many things that slow down the movement through the large intestine and most of them are harmless and do not impact one’s health but can affect one’s wellbeing. Pain medications containing opiates are one of the most common causes of drug-induced constipation. Stress, anxiety, and depression can also alter the function of the large intestine causing things to slow down. Certain diets, particularly those that are low in fiber, can cause temporary constipation. In some cases, the large intestine just doesn’t move as quickly as we would like.
Discussing symptoms with a physician can usually uncover some of the causes of constipation. Blood testing can sometimes help. Colonoscopy can sometimes be useful if there is any suspicion for narrowing in the intestines causing a blockage which can sometimes occur with colon cancer or large polyps.
Once the dangerous causes of constipation have been ruled out, treatment for constipation usually consists of increasing physical activity, dietary changes to increase fiber, using fiber supplements, and sometimes medications. Light to moderate exercise has been shown in multiple studies to help stimulate bowel function to have more regular bowel movements. Fiber supplements like psyllium husk (Metamucil) contains natural fibers which are non-digestible plant products. Other fibers include bran as well as semi-synthetic fibers such as Benefiber and Citracel.
Medications, or laxatives, can be divided into four categories.
• Osmotic laxatives, such as Miralax and lactulose, function much like fiber and help hold more water in the large intestines. These are extraordinarily safe medications because they do not alter any chemical receptors or nerves in the body but just change the osmotic gradient in the large intestine. These medications are not absorbed into the body and are eliminated with a bowel movement.
• Stimulant laxatives, such as Senna or bisacodyl, stimulate the large intestine to have a bowel movement. These medications are available over the counter and are safe for short-term and long-term use. Older versions of these medications were found to be unsafe and were removed from the market many decades ago, but the current medications are safe for long-term use.
• Secretory laxatives, such as Linzess, Amitiza, and Trulance, encourage the body to secrete more fluid into the small intestine to act as a “flush” and push the bowel movement out. These are available as a prescription and are very well tolerated and safe for long-term use.
• Opiate blockers, such as Relistor and Movantik, are only indicated for those using opiate containing pain medications. These medications will block the opiate effect in the intestines while still allowing the anti-pain effect of the opiates.
In summary, most constipation in the United States is caused by a variety of things that can slow down the large intestines. Discussing these symptoms with a gastrointestinal expert can help identify some of the causes of constipation and find ways to reverse them. Also, some constipation can be caused by serious conditions such as colon cancer so further testing may be required. Once the causes of have been identified, there are many safe and sensible therapies to treat constipation and improve one’s quality of life.
