Low FODMAP Diet Boosts IBD Relief But Lowers Bifidobacterium longum

Low FODMAP Diet Boosts IBD Relief But Lowers Bifidobacterium longum

Quick Summary: A study tested a low FODMAP diet on people with inactive inflammatory bowel disease (IBD) who still had gut troubles. It helped more people feel better and improved their quality of life compared to a regular diet. But it also lowered levels of helpful gut bacteria like Bifidobacterium longum, without changing overall inflammation.

What The Research Found

Researchers looked at how a low FODMAP diet affects gut symptoms, the microbiome (the community of bacteria in your stool), and inflammation in IBD patients whose disease was under control but who had ongoing issues like bloating or pain.

• More people on the low FODMAP diet (52%) reported good relief from gut symptoms, compared to just 16% on the control diet.
• IBS-like symptom scores dropped more with low FODMAP (by about 67 points) than the control (by 34 points), though the difference wasn't strongly significant.
• Quality of life scores improved significantly on low FODMAP (81.9 vs. 78.3 on control).
• Key change in the microbiome: Levels of beneficial bacteria dropped, including Bifidobacterium longum (down by about 1.2 times the log fold), Bifidobacterium adolescentis, and Faecalibacterium prausnitzii. These bacteria help regulate the immune system.
• No big changes in overall microbiome diversity or blood markers of inflammation, like C-reactive protein or immune cell types.

In short, the diet eased symptoms short-term but altered some good gut bacteria.

Study Details

• Who was studied: 52 adults with quiescent (inactive) Crohn's disease or ulcerative colitis who had persistent gut symptoms, recruited from two large UK gastroenterology clinics.
• How long: 4 weeks of following the assigned diet.
• What they took: No pills or supplements—just dietary changes. The low FODMAP group got personalized advice to cut back on hard-to-digest carbs like fructose, lactose, and polyols (found in foods like onions, wheat, and some fruits). The control group got standard IBD eating tips. Everyone tracked their food in diaries.

The study was single-blind (patients didn't know which group they were in) and randomized to keep it fair.

What This Means For You

If you have IBD in remission but still deal with gut discomfort, a short low FODMAP diet might help reduce symptoms like bloating or irregular bowels and make daily life feel better. It's safe for 4 weeks and could be a tool to try under a doctor's guidance.

But watch the downside: It lowers Bifidobacterium longum, a "good" probiotic bacteria that supports gut health and immune balance. This might affect long-term gut function, so don't stick to it forever without checking your microbiome—maybe through stool tests. Talk to a dietitian to reintroduce foods gradually and consider probiotics to boost these bacteria if needed. Always pair diet changes with your IBD treatment for the best results.

Study Limitations

• Small group (only 52 people), so results might not apply to everyone and some findings (like symptom score changes) weren't fully conclusive.
• Short 4-week trial means we don't know about long-term effects, like if the bacteria drop rebounds or if symptoms stay improved.
• Single-blind setup could lead to some bias, as the control group had less detailed diet help.
• Starting gut bacteria varied among participants, which might influence results, and the study didn't check how these bacteria's functions (like making anti-inflammatory compounds) changed.

For more, see the full study: PubMed Link.