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Women are no strangers to vague abdominal symptoms such as bloating, gas and bowel irregularities. For the most part, these symptoms occur monthly and are short lived. But for women with irritable bowel syndrome, known as IBS, these symptoms can be constant and interfere with everyday life.

At least twice as many women as men have IBS, a gastrointestinal condition marked by chronic abdominal pain, diarrhea and/or constipation. IBS is most often diagnosed in women in their 20s, and its symptoms can be experienced on and off throughout adulthood. Although it's not fully understood why IBS is more common in women, there are a number of biological and cultural theories. Below, Dr. Lin Chang, an associate professor of medicine at the University of California, Los Angeles School of Medicine, discusses IBS and its impact on women.

What is IBS?
IBS is known as a functional bowel disorder because there is no particular abnormality that causes it. Instead, patients have a cluster of symptoms. The major symptom of IBS is abdominal pain or discomfort. Patients have either diarrhea or constipation, or they might alternate between the two. Other common symptoms are bloating, a sensation of incomplete evacuation, urgency, particularly in patients with diarrhea and sometimes mucus in the stool.

How common is IBS?
Worldwide, the prevalence is between 10 and 20 percent. What's interesting is that about two-thirds of individuals who have IBS don't see a doctor for their symptoms. “I think some people don't realize that they have a condition that their doctors can diagnose or treat,” says Chang. In other situations, people may feel that doctors will think it's “all in their head” because there are no objective tests to diagnose IBS.

What are some reasons for the gender difference?
There are many different reasons why there might be a gender difference. “I think that they include how women and men perceive themselves in society,” says Chang, “and whether they are willing to complain of GI symptoms like gas or diarrhea and constipation.” There are also probably a lot of biologic mechanisms that may have to do with estrogen, the female sex hormone, that affect the gut. So there is a whole host of biologic and psychosocial differences between men and women that may play a role in IBS.

What are the main factors that contribute to the development of IBS?
The mechanisms, or processes, underlying IBS aren't completely understood, but in general, there are three important inter-related factors. One factor is altered gut motility, or motor function. It will either be too fast, so a stool passes too quickly, or it will be too slow, so a stool passes slowly. People can also have increased secretions. The second factor is enhanced gut sensitivity, where the patients will have a heightened sensitivity to contents in the gut, such as stool or gas. So they'll feel bloated, or feel pain or discomfort. The third factor is communication between the brain and the gut. There will be changes in bowel function if the brain and gut are out of sync.

One of the important neurotransmitters, or brain chemicals, that helps with brain/gut interactions is serotonin. Serotonin is produced in the brain and the gut and mediates gut sensation and gut motility. So changes in serotonin can lead to changes in gut motility and sensation and cause IBS symptoms.

Can you explain the relationship between stress and IBS?
Chronic stress plays a predominant role in IBS. It's associated with the onset and exacerbation of symptoms. Usually, these are stressors that have been going on for at least six months, rather than just day-to-day type of stressors. Long-term stressors include a history of verbal, physical or particularly sexual abuse, divorce, moving to a different place to live, changing your job. Such chronic stressors may lead to changes in gut motility and gut sensitivity.

Do men and women handle stress differently?
“I think men and women handle stress differently,” says Chang, “and that definitely plays a role in IBS.” These gender differences have to do with a concept called biobehavioral stress that is based on evolution. Men typically have a fight or flight response, while women respond to stress in a more nurturing way. Women internalize the stress because their role in evolution is to protect their offspring, and not necessarily to get up and fight. Their internalized response leads to enhanced pain sensitivity, while men may respond with enhanced gut motility and an increased heart rate.

How does IBS affect people's quality of life?
Typically, people with IBS will have to miss work or school. They won't be able to go to their usual social activities because they have pain, or they have to run to the bathroom. In addition, other aspects of their life can be affected, such as sleep and sexual function, specifically pain with intercourse. IBS also has an impact on emotional and psychological aspects of life.

How is IBS treated?
There is a whole host of treatments for IBS. They range from pharmacologic therapy with medications to non-pharmacologic treatments, such hypnosis, behavioral training or relaxation therapy. There are some new medications that can treat multiple symptoms of IBS, but typically doctors try to target the most bothersome symptom and then treat that.

What are treatments for constipation?
For the treatment of IBS with constipation, patients typically take some type of laxative. There are many different types of laxatives that a patient could take, either over-the-counter or prescribed, but it doesn't really help their pain. Fiber may also help ease of stool passage, but it doesn't really help any other symptoms.

People with constipation may benefit from medication that works specifically on certain serotonin receptors in the gut. By acting on those receptors, it stimulates gut function and moves stool along the colon much more rapidly. It also causes increased secretion of chloride; fluids make the stool less hard. It also acts on nerves that are involved in transmission of pain.

What are the medical therapies that are available for abdominal pain and diarrhea?
Many patients with IBS and diarrhea, will take anti-diarrheal medications, which you can get over-the-counter. There is also a medication that acts on different serotonin receptor subtypes than the one for constipation. It slows transit of stools in the colon. It was withdrawn from the market, but has been re-approved for release under restricted use.

How can behavioral changes improve the symptoms of IBS?
The relationship between diet and IBS is somewhat complex: It's not so much that there are certain foods that cause IBS symptoms, but some people may have their individual triggers. If patients have an intolerance to dairy products, which is seen often in patients with IBS, they should try to avoid those products. Sometimes fatty foods, caffeine and alcohol can stimulate IBS symptoms. Taking some time to relax and doing timed breathing or relaxation exercises during the day can be very useful. Exercise and drinking plenty of fluids are other simple lifestyle modifications that can minimize IBS symptoms.