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Why Do I Have IBS?

4 potential sources of trouble, and strategies for dealing with the number 2 blues


spinner image cartoon view of the digestive system with germs and bacteria in the intestines and doctors examining the contents of the stomach
Kathleen Fu

Marianne Sarcich, of Wilmington, Delaware, was in her mid-40s when she began to experience uncomfortable bloating and ­diarrhea. An avid runner, she had to dramatically scale back: “If I ran more than a few miles, I’d get an intense case of the runs,” she says.

A gastroenterologist diagnosed her with irritable bowel syndrome (IBS). Then, going through menopause a few years later, Sarcich was surprised that her condition morphed and constipation took its place. Today, at 58, she says her symptoms flip back and forth. “It’s such a strange, puzzling condition,” she muses. “Why me?”

The yuck factor

IBS symptoms include recurrent abdominal pain, bloating and changes in bowel movements (diarrhea, constipation or both). It’s known as a disorder of gut-brain interaction, which means it’s related to how your brain and gut work together. 

“IBS can cause brain hormone changes that cause your gut to be more sensitive, which can lead to symptoms like abdominal pain and bloating,” as well as changes in bowel movements, explains ­William Chey, M.D., a gastroenterologist at the University of Michigan.

“While IBS is most common in your 30s and 40s, people over age 50 represent a substantial proportion of those with IBS,” says Anthony Lembo, M.D., vice chair of research for Cleveland Clinic’s Digestive Disease Institute. And those symptoms often change with age. “As you get older, the nerve endings in your gut become less sensitive,” Lembo says. As a result, abdominal pain and discomfort are less severe. However, chronic diarrhea and constipation remain common and may increase with age.

If you have recurrent abdominal pain or a change in your bowel habits that lasts for more than a couple of weeks, see your doctor right away. They may want to evaluate you for other conditions, such as lactose intolerance, celiac disease, infections and even some serious conditions such as colon cancer or inflammatory bowel disease. Blood and stool tests and in some cases a colonoscopy may be recommended. IBS is likely the culprit if there is no other explanation.

4 IBS causes and solutions

Among the many factors that may lead to IBS:

1. Infection

About 1 in 10 people develop IBS after a bout of gastroenteritis, a.k.a. the stomach bug, explains Yuying Luo, M.D., a gastroenterologist at Mount Sinai Center for GI Physiology and Motility in New York City. Food poisoning can also trigger an inflammatory response in your GI tract.

What you can do: Research results are mixed but suggest that some probiotic strains may improve IBS symptoms, including bloating and gas. The probiotic Bifidobacterium bifidum MIMBb75 has been shown in clinical trials to alleviate IBS symptoms. A 2022 review of studies found that strains of another probiotic, Bacillus coagulans, also significantly helped to improve symptoms.

2. Food sensitivities

“As we age, we have less enzymes to break down disaccharides, a type of sugar found in carbohydrates,” Lembo explains. A 2020 study of patients with IBS symptoms found that about half had a disaccharidase deficiency. Ultraprocessed foods, which include multiple chemical additives, can exacerbate symptoms, Luo adds.

What you can do: Your doctor may suggest that you try what’s called a low-FODMAP diet. This is a diet that, under medical supervision, reduces foods that some people find hard to digest, including certain fruits and veggies, dairy, beans and some grains and nuts. Typically, you follow this elimination diet for two to four weeks, then gradually add these foods back in under the guidance of your doctor. Luo also recommends patients try a Mediterranean diet — with lots of vegetables, fish and olive oil — and avoid processed foods.

3. Genetics

You’re two to three times more likely to develop IBS if it’s part of your family history, Chey says. Researchers in a 2021 study found six gene mutations that raise the risk of IBS; they also found that the same genetic makeup increases the risk for depression and anxiety. “It makes sense, since we know IBS involves both your brain and your gut,” Chey says.

What you can do: The first step is usually to make dietary changes — a low-FODMAP diet, for instance. If that isn’t enough, a laxative or antispasmodic may be prescribed. Tricyclic antidepressants such as nortriptyline (Pamelor) and desipramine (Norpramin) can help with abdominal pain and symptoms of diarrhea by slowing your GI tract.

4. Emotional trauma

“A lot of research suggests that abuse or trauma early in life raises the risk to develop IBS later on,” says Douglas Drossman, M.D., founder and CEO of the Rome Foundation, a nonprofit organization dedicated to education and research on disorders including IBS. Drossman’s research looked at the brain MRIs of abuse survivors with irritable bowel syndrome and found that the part of their brain that controls pain doesn’t work as well as it does in people who have IBS alone.

What you can do: Behavior interventions can help to manage symptoms, especially if yours stem from stress or trauma, says Frank Sileo, a psychologist in Ridgewood, New Jersey. These include:

  • Cognitive behavioral therapy (CBT). This is a type of talk therapy that works to change how you react to certain situations.
  • Hypnosis. More than 30 published research studies show this treatment can help ease the symptoms of IBS.
  • Mahana IBS, a prescription-only digital CBT treatment that’s been cleared by the Food and Drug Administration.

Whatever the cause of your IBS, most people find relief through a combination of dietary changes, behavioral techniques and sometimes medications, Chey says.

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