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Large study finds no link between gluten, IBD risk



Among women without celiac disease, dietary gluten intake was not associated with the risk of developing either Crohn’s disease or ulcerative colitis, investigators reported.

The findings spanned subgroups stratified by age, body mass index, smoking status, and whether individuals primarily consumed refined or whole grains, said Emily Walsh Lopes, MD, gastroenterology clinical and research fellow at Massachusetts General Hospital in Boston. She and associates reported the combined analysis of the prospective Nurses’ Health Study and Nurses’ Health Study II in an abstract released as part of the annual Digestive Disease Week.®

“Avoidance of dietary gluten is common, and many patients attribute gastrointestinal symptoms to gluten intake,” Dr. Lopes said in an interview. “Though our findings warrant further study, the results suggest to patients and providers that eating gluten does not increase a person’s chance of getting diagnosed with inflammatory bowel disease.”

Prior studies have found that many individuals with inflammatory bowel disease avoid gluten and report subsequent improvements in gastrointestinal symptoms, even if they do not have celiac disease. However, it remains unclear whether dietary gluten is a risk factor for new-onset inflammatory bowel disease.

To address this question, Dr. Lopes and associates analyzed data collected from 165,327 women who took part in the Nurses’ Health Study (1986 to 2016) or the Nurses’ Health Study II (1991 through 2017). None of the women had a preexisting diagnosis of celiac disease or inflammatory bowel disease. Dietary gluten intake was estimated based on food frequency questionnaires completed by the women at baseline and every 4 years. The researchers also reviewed medical records to confirm self-reported cases of new-onset ulcerative colitis and Crohn’s disease.

Over 4.02 million person-years of follow-up, 277 women developed Crohn’s disease and 359 developed ulcerative colitis. Gluten intake was not associated with the risk of either type of inflammatory bowel disease, even after the researchers controlled for multiple demographic and clinical risk factors.

After submitting their abstract, Dr. Lopes and coinvestigators expanded the dataset to include a large cohort of men from the prospective Health Professionals Follow-up Study. The final pooled cohort included more than 208,000 women and men followed for more than 20 years. Through the end of follow-up, the researchers documented 337 cases of Crohn’s disease and 446 cases of ulcerative colitis. “Inclusion of the male cohort in the pooled analysis did not materially change our estimates,” Dr. Lopes told MDedge. “That is, no association was seen between gluten intake and risk of either Crohn’s disease or ulcerative colitis in the final cohort.”

She noted that the findings cannot be extrapolated to individuals who are already diagnosed with inflammatory bowel disease. “It is possible that different mechanisms exist to explain how gluten intake impacts those already diagnosed with IBD, and this topic warrants further study,” she said. Also, because the three cohort studies were observational, they are subject to bias. “While we tried to account for this in our analyses, residual bias may still exist.”

Dr. Lopes reported having no conflicts of interest.

SOURCE: Walsh Lopes E et al. DDW 2020, abstract 847.

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