IgG-guided elimination diet effectively reduces IBS-related abdominal pain
Key takeaways:
- More than half of the adults with IBS on an IgG-guided elimination diet reported reduced abdominal pain.
- Those who had IBS with constipation or mixed bowel habits benefited most from the experimental diet.
Adults with irritable bowel syndrome who followed an IgG-guided elimination diet were more likely to experience a reduction in abdominal pain than those on a sham elimination diet, according to a study published in Gastroenterology.
“Because patients with IBS generally associate food as one of their main triggers for IBS symptoms, they’re very interested in dietary therapies,” Prashant Singh, MBBS, assistant professor of internal medicine in the division of gastroenterology and hepatology at Michigan Medicine, told Healio. “Existing dietary therapies such as low-FODMAP are very complex and restrictive for patients. Although past studies have looked at IgG antibody-based diets for IBS, they have had serious limitations.”
To assess the efficacy of an IgG-based elimination diet vs. a sham elimination diet, Singh and colleagues conducted a multicenter, randomized, double-blind trial of 223 adults aged 21 years or older with IBS who were enrolled from eight academic centers in the U.S. between June 21, 2018, and Dec. 31, 2021.
Eligible participants had an average daily abdominal pain intensity score between 3 and 7.5 on an 11-point Likert scale during a 2-week run-in period. The researchers randomly assigned them to an experimental diet group (n = 118; mean age, 39.5 years; 76.3% women) or sham diet group (n = 105; mean age, 40.7 years; 81% women). Those in the elimination diet group eliminated foods that received a positive result on a novel IBS-specific IgG assay (inFoods IBS, Biomerica), whereas those in the sham diet group did not eliminate the food they tested positive for but instead eliminated foods from the same food group.
The primary outcome of the study was at least a 30% reduction from baseline in mean daily abdominal pain score for 2 or more of the last 4 weeks of the treatment period.
Secondary outcomes included change from baseline in abdominal pain intensity, bloating, stool consistency, IBS Symptom Severity Score (IBS-SSS), among others.
Overall, 59.6% of participants who followed the experimental diet met the primary outcome vs. 42.1% of those on the sham diet (P = .02), according to the researchers.
They noted this improvement appeared more robust in subgroup analyses specifically looking at participants who had IBS with constipation (IBS-C; 67.1% vs. 35.8%) and those with IBS with mixed bowel habits (IBS-M; 66% vs. 29.5%).
“One thing that was a bit unexpected was that the elimination diet seemed to work a lot better for patients with IBS-C and IBS-M than those who had IBS with diarrhea, or IBS-D,” Singh told Healio. “This was surprising because most of the previous diet studies have been done in patients with IBS-D and even found it more effective for these patients.”
Lastly, the researchers found that changes from baseline in abdominal pain intensity, bloating and IBS-SSS were numerically greater among those who followed the experimental diet vs. those on the sham diet.
Singh and colleagues acknowledged several study limitations, including the lack of detailed information on compliance and the fact that the study was not powered for the subgroup analysis.
“The next step for our research is probably to conduct a larger phase 3 study focusing on IBS-C and IBS-M patients,” Singh said. “If it holds true that IgG-based diets work better than sham diets in these subgroups of patients, we may have a new way to approach nutrition therapy in patients with IBS.”
For more information:
Prashant Singh, MBBS, can be reached at singhpr@med.umich.edu.
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