Patients with celiac disease who continued to have irritable bowel syndrome–like symptoms despite a strict gluten-free diet reported sustained symptom improvement five years after trying a low fermentable oligo-, di-, monosaccharides and polyols (FODMAP) diet, according to a follow-up study of a randomized controlled trial.
The study, published in Gastro Hep Advances, found that nearly half of patients originally assigned to the low FODMAP intervention were still fully or partly following the diet five years later, usually in a personalized form after reintroducing tolerated foods. Many also reported better GI symptoms and improved general health compared with before the original trial.
“This study is important because long-term data on the combined low FODMAP- and gluten-free diet is missing, and there are few treatment options for celiac patients with ongoing symptoms despite strict adherence to a gluten-free diet,” one of the study authors, Frida van Megen, PhD, a clinical dietitian in the department of nutrition at the University of Oslo, Norway, told GI & Hepatology News.
The report builds on findings from the group’s 2022 randomized controlled trial, which showed that adding a moderately low FODMAP diet to a gluten-free diet helped reduce persistent symptoms in patients with celiac disease who were in serologic and histologic remission but still had irritable bowel syndrome–like symptoms.
Persistent GI symptoms affect about 38% of patients with celiac disease, even when they follow a gluten-free diet and show healing of the intestinal lining, the authors noted. Before attributing these symptoms to functional GI disorders, physicians should first rule out complications such as enteropathy-associated T-cell lymphoma, they said.
The exploratory follow-up study included all 70 participants from the original trial, which was conducted from 2018 to 2019. A total of 45 patients responded, including 23 from the low FODMAP diet group and 22 from the control group.
In the original trial, patients in the intervention group received individual counseling on following a combined gluten-free and low FODMAP diet for four weeks. Patients who showed improvement were then given guidance on how to gradually reintroduce and personalize foods. Patients in the control group initially continued their usual gluten-free diet but were later offered a group educational session on the low FODMAP approach.
Among patients in the original control group, 41% later tried the low FODMAP diet. Reasons for not trying the diet included that it was considered “too demanding,” lack of motivation, or having only minimal symptoms.
During the restriction phase, 83% of patients in the intervention group reported symptom improvement, compared with 56% of crossover patients who later tried the diet without personalized counseling.
At five years, 48% of the original intervention group and 44% of crossover patients reported fully or partially following the diet. Most participants had moved into the personalization phase, which reintroduces tolerated high-FODMAP foods to increase dietary variety and help maintain nutritional adequacy.
Among patients who reintroduced foods, fructans were the most common symptom trigger, reported by 54% of participants. Mannitol was reported by 38%, while galactans, lactose, and fructose plus sorbitol were each reported by 35%. Other reported triggers included alcohol, carbonated beverages, stress, poor sleep, soy, and oats.
In other findings, 70% of patients in the intervention group said their gastrointestinal symptoms were “a little” or “much” better than before the original trial, compared with 50% of controls. Nearly half of patients in the intervention group also reported improvements in general health.
Patient-reported symptom scores also improved over time. In the intervention group, mean Gastrointestinal Symptom Rating Scale–Irritable Bowel Syndrome scores decreased from 40.7 at baseline to 34.4 at five years, compared with a decline from 36.2 to 34.2 in controls. Celiac Symptom Index scores improved from 40.1 to 32.8 in the intervention group and from 38.5 to 35.8 in controls.
“We were surprised about how many participants still were partly adhering to the low FODMAP-diet after five years,” Dr. van Megen said. “Our study indicates that the combined low FODMAP- and gluten-free diet could be a long-term treatment option for celiac patients with ongoing IBS-like symptoms despite following a strict gluten-free diet and with biopsy-verified remission of celiac disease.”
However, no statistically significant differences were seen between the diet and control groups at long-term follow-up. The investigators said this may have been due to limited statistical power, crossover use of the diet among controls, and the relatively small study population.
The study also raised potential nutritional concerns. Weight loss was reported by 44% of patients in the intervention group, compared with 23% of controls, suggesting that the combined gluten-free and low FODMAP diet may be too restrictive for some patients.
She and her coauthors emphasized the importance of working with a dietitian to help patients safely add foods back into their diet while making sure they get the nutrients they need.
The study was funded by the Norwegian Celiac Association and the Throne Holst Nutrition Research Foundation. The original randomized controlled trial was funded by the South-Eastern Norway Regional Health Authority. The authors reported no conflicts of interest.