People with irritable bowel syndrome with diarrhea (also called IBS-D) often suffer from symptoms like stomach pain and frequent, loose bowel movements.
Many of them say their symptoms get worse after eating certain foods.
In a new study, scientists found that a special eating plan called the low FODMAP diet can do more than just reduce symptoms—it may also help repair a problem called “leaky gut.”
The study was led by Dr. Prashant Singh, a stomach doctor at Michigan Medicine. The results were published in the journal Gastroenterology. This is the first study to show that the low FODMAP diet can actually improve the gut lining and reduce activity of certain immune cells in people with IBS-D.
The gut lining acts like a protective wall. It keeps harmful things inside the intestines from leaking into the rest of the body. But in some people, this wall becomes too “leaky.” This is what’s known as “leaky gut.”
When this happens, harmful substances from bacteria can pass through and irritate the nerves in the gut. This can cause pain and other symptoms in people with IBS-D.
The low FODMAP diet removes certain types of sugars that are hard to digest. These sugars are found in foods like onions, garlic, beans, apples, and milk. When people with IBS eat these foods, their symptoms often get worse.
In this study, 48 people with IBS-D followed a low FODMAP diet for four weeks. They were given all their meals as part of the study. By the end, 42 people completed the diet. Out of those, 34 people saw a clear improvement in their symptoms. They had less diarrhea and stomach pain.
Before and after the diet, the researchers checked how well the gut barrier was working. They also looked at immune cells called mast cells. These cells can become very active in IBS-D and cause inflammation. The study found that after the diet, the gut barrier was stronger, and there were fewer active mast cells in the lining of the colon.
To better understand how this works, the scientists also did experiments on mice. They gave mice stool samples from the IBS-D patients before and after the diet. Mice that received samples from people who were on the high FODMAP diet had more gut problems.
Their gut barriers were weaker, and they had more signs of inflammation. One substance the scientists studied was called LPS, which comes from gut bacteria.
Too much LPS can trigger the immune system and make the gut barrier leakier. The mice had higher levels of LPS when exposed to stool from patients on a high FODMAP diet.
This shows that diet changes the gut bacteria, which can then affect the immune system and the gut barrier. These findings help explain why the low FODMAP diet works, not just by easing symptoms but by healing the gut itself.
Doctors might now think about using medicines that calm mast cells, especially for patients who can’t follow the low FODMAP diet. “Our study shows diet is not a quick fix—it’s a real solution for some patients with IBS,” said Dr. Singh.
The team hopes future studies will include more people, especially those who don’t get better with the low FODMAP diet, and explore other types of IBS as well.
In summary, this study adds strong evidence that the low FODMAP diet helps people with IBS-D in more ways than one. It doesn’t just make people feel better—it may also fix one of the root problems in their gut. This is important news for both patients and doctors looking for long-term solutions.
For more information about gut health, please see recent studies about the crucial link between diet, gut health, and the immune system and results showing that Low-gluten, high-fiber diets boost gut health and weight loss.
For more information about gut health, please see recent studies about Navigating inflammatory bowel disease (IBD) with diet and results showing that Mycoprotein in diet may reduce risk of bowel cancer and improve gut health.
The study is published in Gastroenterology.
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