For people with irritable bowel syndrome (IBS), food can feel like the enemy. Certain meals trigger bloating, diarrhea and abdominal pain. But a dietary approach known as the low FODMAP diet has long been a trusted tool for relief.
The diet limits certain types of carbohydrates called FODMAPs, short-chain sugars found in foods like wheat, beans, onions and some fruits, that are difficult for some people to digest. By reducing these fermentable carbs, the diet can help ease IBS symptoms.
Now, new research suggests it may do more than ease symptoms. It could help repair the gut itself.
In a study published in Gastroenterology, researchers at Michigan Medicine found that people with diarrhea-predominant IBS (IBS-D) who followed a low FODMAP diet for four weeks had improved gut barrier function, commonly referred to as “leaky gut.” The diet also reduced the number and activation of mast cells, a type of immune cell that drives inflammation in the gut.
“Diet and microbiome have been believed to be related to leaky gut, but the reasons why were not well understood,” said senior author Dr. Prashant Singh, a gastroenterologist at Michigan Medicine. “This research illuminates the mechanism of how food can interact with the gut microbiome and gut immune system to influence colonic barrier dysfunction — and validates the low FODMAP diet as a treatment option that not only improves symptoms but underlying dysfunction in IBS.”
The trial included 48 people with IBS-D, 42 of whom completed the study. Participants ate only low FODMAP meals provided by the researchers during the four-week restriction phase. Of those who completed the trial, 34 reported less diarrhea and abdominal pain.
Further analysis offered clues to how the diet works. Using mice treated with stool from participants, researchers showed that a high FODMAP diet can raise levels of lipopolysaccharides (LPS), molecules made by gut bacteria that can trigger mast cells and make the intestinal barrier more permeable. The low FODMAP diet appeared to reverse this effect, lowering LPS levels and calming mast cell activity.
The findings support using the low FODMAP diet as a first-line approach for IBS-D and point to mast cell-targeting treatments as an alternative for patients who cannot follow the diet.
“Our study shows diet is not a quick fix — it’s a real solution for some patients with IBS,” Singh said.
This study was supported by the National Institute of Diabetes and Digestive and Kidney Diseases.