IBS affects one in five Australians. What’s the best way to treat it?

Irritable bowel syndrome is one of the most common and perplexing conditions gastroenterologists treat. It affects around one in five people in Australia, with more women diagnosed than men, and causes symptoms so debilitating they can be hard to ignore, including abdominal pain, bloating, diarrhoea and constipation.

Scientists don’t know exactly what causes IBS, and there is no cure, so the condition is often difficult to manage. But a new study in the journal The Lancet Gastroenterology and Hepatology offers clues for how best to find relief.

IBS affects around one in five people in Australia.Credit: iStock

What is IBS? How is it usually treated?

The telltale symptoms of IBS are chronic abdominal pain, along with diarrhoea, constipation or both, said Dr. Brian Lacy, a gastroenterologist at the Mayo Clinic in Jacksonville, Florida. Bloating is also a common complaint, he said.

Treatments often include managing the symptoms with changes to your diet or taking medications, which can include over-the-counter laxatives and antidiarrheals; certain antidepressants; and other prescription medications, including linaclotide and lubiprostone, both of which can increase fluid in the gut and the movements of your intestines. Yet few studies have examined whether dietary changes or medications are best for relief.

The most robust research available on dietary strategies has found that following a low-FODMAP diet — which involves avoiding foods including wheat-based products, legumes, some nuts, certain sweeteners, most dairy products and many fruits and vegetables — can reduce IBS symptoms in most people, said Dr. William Chey, a gastroenterologist at Michigan Medicine.

Treatments often include managing the symptoms with changes to your diet.Credit: iStock

But a low-FODMAP diet is challenging to follow; it’s restrictive and requires carefully reintroducing foods to identify the ones you can’t tolerate, Chey said.

Some research also supports simpler tweaks, such as eating more slowly; having regular, smaller and more frequent meals; and limiting coffee, tea, carbonated beverages, alcohol, and fatty or spicy foods, said Sanna Nybacka, a dietitian and postdoctoral researcher at the University of Gothenburg in Sweden, who led the new study.

After noticing that some of their patients also found relief with a low-carbohydrate diet, Nybacka and her colleagues decided to develop a trial to compare several treatment options.

What did the new study find?

The trial, conducted at a hospital clinic in Sweden, included 241 women and 53 men with moderate to severe IBS. Participants were randomly assigned to one of three treatment groups for four weeks.

In the “medication” group, researchers gave each of the participants one of eight IBS medications based on their main symptoms, Nybacka said. If their primary complaint was constipation, for example, researchers gave them a laxative called sterculia; if their main symptom was diarrhoea, they gave them an antidiarrheal called loperamide (also sold as Imodium).

A second group was given groceries and recipes to help them follow a low-FODMAP diet, which included foods such as rice, potatoes, quinoa, wheat-free bread, lactose-free dairy products, fish, eggs, chicken, beef and various fruits and vegetables. Nybacka said they were also encouraged to eat slowly, have regular, small meals, and limit other foods and drinks that could trigger symptoms.

The last group received groceries and recipes to follow a low-carbohydrate, high-fat diet, which focused on foods including beef, pork, chicken, fish, eggs, cheese, yoghurt, vegetables, nuts and berries.

After four weeks, 76 per cent of those in the low-FODMAP group and 71 per cent of those in the low-carbohydrate group reported significant reductions in IBS symptoms; 58 per cent of those in the medication group reported significant improvements, too. Among all participants who noticed improvements, those in the diet groups reported much greater symptom relief than those in the medication group, Nybacka said.

Because the low-FODMAP diet had been considered the most effective diet for managing IBS, Nybacka said she was surprised to find that the low-carbohydrate diet had worked essentially as well.

What’s the bottom line?

Chey said the study was well done and provided “real data” to support what many doctors have observed: That “diet therapy is at least as good and probably better” than medication, he said.

But the trial had some limitations. Because it was conducted on a relatively small group of people at just one medical centre in Sweden, it will need to be replicated with larger and more diverse groups of people, he said.

It is also possible that the trial underestimated the value of medications. Some IBS drugs may need to be taken for more than four weeks before they provide a full benefit, said Dr. Lin Chang, a gastroenterologist at UCLA Health. And some medications, such as plecanatide, tenapanor and rifaximin, which can be effective for some people and are available in the United States, were not included in the study, she said. So it’s hard to make a blanket statement about how effective all medications are.

For some, a combination of diet and medication may work best, Chang said, but that wasn’t tested in this study.

Researchers also gave trial participants a lot of support in adopting the diets, so it’s unclear if everyone trying them on their own will have the same success, Nybacka said.

Still, the findings confirm that dietary changes can be an important option for treating IBS, Chey added.

People should talk with their doctors before adopting either diet, Nybacka said. In the trial, there was a small increase in blood cholesterol levels among participants in the low-carbohydrate group, suggesting a reason for caution for those at risk of heart disease, Nybacka said. And both the low-carbohydrate and low-FODMAP diets can be quite restrictive, Chey said, and may not be appropriate for those who have or are at risk of developing an eating disorder.

But for everyone else, it can be encouraging to know that you can manage your symptoms simply “by eating differently,” Nybacka said. The more researchers learn about which diets work best for people with IBS, she said, the better.

The New York Times

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