🟢 Strong clinical evidence (randomised controlled trial)

Study at a glance

• Participants: 150 adults
• Condition: Irritable Bowel Syndrome (IBS)
• Study type: Randomised, double-blind, sham-controlled trial
• Duration: 12 weeks

What was done

Participants took a food-specific IgG blood test. They were then randomly assigned to follow either:

• A diet removing foods identified by the test, or
• A sham diet (removing unrelated foods)

Neither the participants nor researchers knew which diet they were on until the end of the study.

What improved

After 12 weeks:

• People following the IgG-guided diet had greater improvement in IBS symptoms compared to the control (sham) diet
• The difference between groups equated to around a 10% greater reduction in overall symptom scores

Importantly:

• Participants who strictly followed the diet experienced around twice the improvement compared to those who did not fully follow it
• Improvements included abdominal pain, bloating and bowel symptoms

In practical terms, this means participants following the IgG-guided diet experienced meaningfully greater symptom relief than those following a non-targeted diet.

Key takeaway

Following a diet based on IgG test results led to greater symptom improvement than a control diet, with the largest benefits seen in those who followed the diet closely.

What this means

This study provides strong clinical evidence that removing foods identified by IgG testing may help reduce IBS symptoms. The use of a blinded control group strengthens confidence that the improvements were not simply due to expectation or placebo.

🟢 Evidence strength

Strong clinical evidence (randomised controlled trial)

Full citation

Atkinson et al. 2004 IBS IgG trial

Atkinson W, Sheldon TA, Shaath N, Whorwell PJ.
Food elimination based on IgG antibodies in irritable bowel syndrome: a randomised controlled trial.
Gut. 2004;53(10):1459–1464.

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