CHARLOTTE, NC — Some people with irritable bowel syndrome (IBS) may benefit from eliminating foods deemed problematic by a new diagnostic tool, new research reveals.
The tool identifies increases in immunoglobulin G (IgG) antibody levels caused by food allergies, showing which offenders to remove from the diets of IBS patients. Eliminating problem foods resulted in a significant difference on overall measures of improvement and symptom relief, according to the prospective, multicenter, double-blind study.
The study results were presented at the 2022 American College of Gastroenterology (ACG) Annual Meeting in Charlotte, North Carolina, which will be held in person and virtually.
Whether IgG-based elimination diets help IBS patients is highly controversial, even though more than three-quarters of patients associate their symptoms with eating a meal, study co-lead investigator William Chey, MD, professor of medicine and director of the gastrointestinal physiology laboratory at the University of Michigan at Ann Arbor, said Medscape Medical News.
“This is one of the largest and most rigorous randomized controlled trials to be done on an IgG-based elimination diet,” Chey said.
The researchers chose the most common foods that have caused increased levels of IgG antibodies in previous IBS research.
Milk, corn, eggs, oats, onion, soy, tree nuts, wheat and chicken were most often removed from the diet, said Anthony Lembo, MD, the other lead researcher. of the study, gastroenterologist at Beth Israel Deaconess Medical Center and professor of medicine at Harvard Medical School in Boston, Massachusetts.
study design
Even though food sensitivities are common in people with IBS, “results from self-directed elimination diets are poor,” the researchers note.
To determine whether a new proprietary IgG panel (InFoods, Biomerica) might help improve IBS symptoms, Lembo, Chey and colleagues studied 223 adults with IBS enrolled at six centers.
After a 2-week baseline, those who tested positive for one or more food allergies and had an average daily IBS abdominal pain intensity score of 3 to 7.5 (on a scale of 1 to 10 ) were evaluated.
Participants were randomly assigned to a treatment diet group or a sham diet group for 8 weeks. Those in the treatment diet group were instructed to eliminate foods to which they tested allergic, while the sham diet group eliminated foods to which they tested negative. The groups were balanced in terms of the number of foods eliminated.
People in both groups reported daily bowel habits, bloating, and abdominal pain intensity scores. They also conducted weekly assessments using the IBS Adequate Relief, Subject’s Global Assessment of Relief (SGA), and Global Improvement Scale (GIS) instruments.
Improvement of symptoms
From baseline, the treatment group showed a greater decline in abdominal pain intensity (IBS-API) and bloating scores compared to the sham group, according to an intention-to-treat analysis at 8 weeks. However, these changes did not reach statistical significance.
However, participants in the treatment group experienced significant improvements on GAS (P < .001) and GIS (P < .001).
A subgroup of patients, 149 people with non-SCI diarrhea, showed the greatest decrease in symptoms from baseline on the IBS-API (P = 0.014) and IBS-Bloating (P = 0.021) measurements. They also reported the best improvements on the GIS (P < .001) and SGA (P < .001).
No significant adverse events were noted during the study.
The study offers “credible evidence that this IgG-based elimination diet provides overall symptom benefits in some IBS patients – and this benefit appears to be most robust in IBS patients without diarrhea,” Chey said.
The researchers note that the findings should help guide further studies.
“We need to repeat this study in a larger cohort of IBS patients,” Lembo said. “In addition, the long-term impact of eliminating specific foods needs to be explored further.”
An unexpected discovery
Prior to this study, data suggested that modifying diet based on a patient’s IgG antibody response to food could alleviate IBS symptoms, said Lin Chang, MD. Medscape Medical Newswhen asked to comment.
“This study provides further evidence that dietary IgG panels may provide overall relief of IBS symptoms in at least some patients, but with a less robust effect on abdominal pain and bloating,” added Chang, vice chief of the Digestive Diseases Division at UCLA Health. in Los Angeles, California.
“It’s a bit unexpected to see a greater benefit in non-IBS-D patients,” she said. “I would have expected a greater advantage in IBS-D.”
Chang also noted that more studies are needed.
For more information, see the “AGA Clinical Practice Update on the Role of Diet in Irritable Bowel Syndrome: Expert Review,” authored by Chey, Chang, and colleagues.
The study was independently funded. Chey said he is a consultant for Biomerica, as well as AbbVie, Allakos, Alnylam, Arena Pharmaceuticals, Commonwealth Diagnostics International, Gemelli Biotech, Ironwood Pharmaceuticals, ISOThrive, Nestle, Phathom Pharmaceuticals, Progenity, Redhill, Urovant Sciences and Vibrant Pharma, as well as d to be a consultant and to receive grant/research support from QOL Medical and Salix Pharmaceuticals, and to own stock options in GI OnDEMAND, ISOThrive and Modify Health. Lembo said he is a consultant for Alkermes, Arena, Bayer, Gemelli Biotech, Ironwood, OrphoMed, Salix, Shire, Takeda Pharmaceuticals and Vibrant, as well as an advisor for Vibrant and holds stock options in Bristol-Myers Squibb and Johnson & Johnson. Chang has did not report any relevant financial relationships.
CAG 2022. Abstract #B0274. CAG Presidential Poster Award. Presented October 24, 2022.
Damian McNamara is a Miami-based staff reporter. It covers a wide range of medical specialties, including infectious diseases, gastroenterology and critical care. Follow Damien on Twitter: @MedReporter.
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