Harvard Health Letter

Best ways to battle irritable bowel syndrome

Get to know your triggers and ways to prevent flare-ups.

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Irritable bowel syndrome may be due to an overgrowth of bacteria in the small intestine or nerve problems.

Cramping, abdominal pain, bloating, diarrhea, and constipation are tough to handle at any time. But if a combination of these symptoms occurs over three or more months, you may have a condition called irritable bowel syndrome (IBS). It's the most common diagnosis made by gastroenterologists, accounting for as many as 3.5 million physician visits per year. "I see someone with this condition every day," says gastroenterologist Dr. Jacqueline Wolf, associate professor of medicine at Harvard Medical School.

Causes

There are many theories about what exactly causes IBS: problems with the nerves or muscles in the gut, an overgrowth of certain bacteria in the small intestine or a change in bacteria in the colon, an inability to digest certain foods, or stomach or bowel inflammation. Some people have symptoms every day, while others experience long symptom-free periods. IBS does not lead to serious disease, but it does significantly affect your quality of life. "People say it's ruining their lives or that they have a constant ache after they eat," says Dr. Wolf.

While we don't know what causes IBS, we do know that flare-ups are often triggered by food, caffeine, stress, carbonated drinks, artificial sugars, or infectious diarrhea. The more IBS episodes you have, the more sensitive your gut becomes to triggers.

Fighting back

Dr. Wolf uses a number of different strategies to help people battle IBS. She recommends trying dietary changes first. You may be unable to digest insoluble fiber found in the skin of fruits and vegetables, or a sugar in dairy products called lactose. "It's different for everyone," says Dr. Wolf. She suggests a diet approach that eliminates foods with poorly digested sugars and fibers known as FODMAPs (see "The IBS buzzword: FODMAPs").

Dr. Wolf also recommends probiotics, which are colonies of good bacteria that are typically freeze-dried. You can find them in most drug stores and supermarkets, as capsules or tablets to swallow and loose powder to sprinkle on food. You'll want a product that's labeled for viability through the end of shelf life, not at the time of manufacture. "The type of bacteria in the probiotic is very important," says Dr. Wolf. Her research shows that a type of bacteria called Bifidobacterium is often effective at relieving the symptoms of IBS.

Another supplement she suggests is enteric-coated peppermint capsules, which are available over the counter. "It can't be used in people with heartburn, but otherwise it decreases cramping just as well as a common antispasmodic medication, and it also decreases bloating," says Dr. Wolf.

Next steps

Finding a strategy that works may take time and experimentation. Once you do develop a routine that relieves symptoms, you'll have to keep it up in order to avoid flare-ups.

If dietary changes, peppermint, and probiotics don't give enough relief, Dr. Wolf may prescribe a medication for cramping, bloating, or diarrhea. And if symptoms still persist, she says a blood test, CT scan of the colon, or a colonoscopy may be necessary to check for other potential causes of the symptoms. Women may need pelvic exams as well. 

The IBS buzzword: FODMAPs

The hot topic in flare-ups for irritable bowel syndrome (IBS) is a group of poorly digested sugars and fibers called FODMAPs. (That abbreviation is shorthand for a technical term referring to molecular structure.) The most common food sources of FODMAPs are wheat, rye, onions, garlic, legumes, dairy products, honey, apples, watermelons, peaches, apricots, blackberries, high-fructose corn syrup, and artificial sweeteners. These molecules are digested by gut bacteria, which produce gas and bloating. It's worth it to reduce these foods to see if your symptoms improve.

Increasing evidence, including a study in the January 2014 Gastroenterology, shows that a diet low in FODMAPs helps to tame IBS symptoms. "I've definitely seen this work. In fact, I've been using it to help people for a long time," says gastroenterologist Dr. Jacqueline Wolf, associate professor of medicine at Harvard Medical School. Other research shows that FODMAPs may even be the reason why diets low in gluten (which are also low in FODMAPs) help relieve symptoms of people who believe they have gluten sensitivity—digestive problems triggered by gluten, a protein found in some whole grains such as barley, rye, and wheat.

Unfortunately, some of the foods that are high in FODMAPs—like many fruits and vegetables—also contain health-promoting chemicals. That's why it's best to work with a dietician to develop a low-FODMAP menu that fits your lifestyle.