Causes and Symptoms of IBS

Irritable bowel syndrome (IBS) is one of the most common—and frequently misunderstood—digestive disorders. One in five adults in the United States has symptoms of IBS, yet only a small number of people with symptoms seek treatment.

The good news is that:

• IBS can often be effectively managed once an accurate diagnosis is made—although you will require a number of tests to rule out other diseases; and

• It appears that the disorder does not cause long-term damage to the digestive tract or lead to serious complications.

Causes of irritable bowel syndrome

The cause of IBS is not well understood. Some researchers have pro- posed that IBS may result from malfunctions in the rhythmic muscle contractions that propel food through the small and large intestines. Contractions that are too strong can push food contents through the intestines too quickly, causing diarrhea and bloating; weak contractions can lead to constipation.

Because women develop IBS two to three times more often than men, some experts hypothesize that symptoms may be related to hormone levels. Other proposed causes include hypersensitivity to pressure in the small and large intestines, an imbalance in neurotransmitters (chemicals found in both the brain and digestive tract) and infection. A number of studies have associated IBS with an overgrowth of intestinal bacteria.

Psychological factors may also play a role. IBS and mental stress appear to be closely related, and people with depression or anxiety tend to be more susceptible to IBS. Studies also show an increased risk of IBS in women who have been physically or sexually abused.

Recent research has focused on a specific cluster of carbohydrates that may trigger IBS symptoms, with findings indicating that patients who avoid foods containing these carbohydrates may be able to get their symptoms under control. The carbohydrates—fermentable oligosaccharides, disaccharides, monosaccharides and polyols, collectively referred to as FODMAPs—are found in a wide variety of plant-based foods.

A low-FODMAP diet is quite restrictive, however, requiring the elimination of wheat and most dairy products, as well as many common and popular fruits and vegetables such as apples, peaches, broccoli, and sweet corn. Guidance from a nutritionist or dietitian may be needed to follow this type of diet correctly.

Symptoms of irritable bowel syndrome

The symptoms of IBS usually first appear during the teenage years or young adulthood, although the condition can develop at any time, even in older adults. One of the most common symptoms is abdominal discomfort or pain, accompanied by diarrhea, constipation or alter- nating bouts of constipation and diarrhea. Other symptoms include abdominal bloating, a feeling of incomplete emptying of the bowels after passing stool, and mucus in the stool.

If you have IBS, you may find the symptoms distressing and disruptive to your life. The severity of symptoms varies: Most people experience mild symptoms, although they can become more severe and even disabling at times. Some women report that IBS symptoms are worse before and during their menstrual periods. The symptoms may even awaken some people in the middle of the night.

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HealthAfter50 was published by the University of California, Berkeley, School of Public Health, providing up-to-date, evidence-based research and expert advice on the prevention, diagnosis, and treatment of a wide range of health conditions affecting adults in middle age and beyond. It was previously part of Remedy Health Media's network of digital and print publications, which also include HealthCentral; HIV/AIDS resources The Body and The Body Pro; the UC Berkeley Wellness Letter; and the Berkeley Wellness website. All content from HA50 merged into in 2018.