Testing How Food Affects Gut Bacteria and Belly Pain in IBS

Plain-English translation of NCT07688044 on ClinicalTrials.gov ↗ · Source last updated July 2026 · How we translate trials

What is this trial?

This study explores how certain types of carbohydrates called FODMAPs — found in many everyday foods — trigger belly pain in people with irritable bowel syndrome (IBS). Researchers will have you follow a low-FODMAP diet for 6 weeks, then gradually reintroduce different carbohydrates one at a time to see which ones cause your symptoms to flare up. They'll also study your gut bacteria through stool samples to understand whether the bacteria themselves are responsible for your pain.

About 1 in 20 Canadians have IBS, and while avoiding FODMAPs helps roughly half of patients feel better, it's hard to stick to for long because these carbohydrates are in so many foods. This research aims to pinpoint exactly which FODMAPs hurt the most and why, so doctors can give patients more personalized, easier-to-follow dietary advice.

Do you qualify?

You likely qualify if…

you are between 18 and 70 years old
you have been diagnosed with IBS based on standard diagnostic criteria
you have significant belly pain (a score above 12 on a standardized pain scale)
you do not have other digestive conditions like celiac disease or inflammatory bowel disease

You likely don't qualify if…

you have had major digestive surgery like bowel removal or gastric bypass
you have taken antibiotics or probiotics in the past month, as these can change your gut bacteria
you are pregnant, breastfeeding, or being treated for an eating disorder or serious mental health condition
you have a body mass index above 35, as this may affect how your gut responds to the diet
you are allergic to any ingredients in the study foods or have taken new medications in the past 4 weeks

What participation looks like

You will follow a low-FODMAP diet for 6 weeks total. If your symptoms improve by at least 50% after the first 2 weeks, you'll move into the challenge phase, where you'll add back one type of carbohydrate at a time for 4 days, rest for 3 days, and repeat this cycle with three different FODMAP types plus a control carbohydrate. Throughout the study, you'll provide stool samples so researchers can track changes in your gut bacteria and see which carbohydrates — and which bacteria — are linked to your pain.

Testing How Food Affects Gut Bacteria and Belly Pain in IBS

What is this trial?

Do you qualify?

What participation looks like

Trial locations(1 site)