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Individualized IBS diets reduce symptoms better than placebo
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Individualized elimination diets guided by leukocyte activation tests reduced symptoms of irritable bowel syndrome better than a sham diet in a randomized controlled trial.
Researchers concluded that this dietary strategy may enable patients with IBS to alleviate their symptoms with less food restrictions than those required by the low FODMAP diet, which could improve long-term adherence.
“We didn’t expect results like this,” Ather Ali, ND, MPH, MHS, assistant professor of pediatrics and of medicine at Yale School of Medicine, said in a press release. “The people who consumed the diet consistent with the test did significantly better than people on the sham diet.”
In a parallel-group, double-blind trial, Ali and colleagues analyzed blood samples from 58 adults with IBS (mostly white women) using a leukocyte activation test to measure immune response to individual foods. Then they randomly assigned participants to adhere to a diet restricting foods consistent with the test results, or to a sham diet restricting foods inconsistent with the test results, for 4 weeks.
An average of 13 foods were eliminated among all participants out of a possible 200 that were tested, the most common of which included strawberries and cinnamon (low FODMAP foods) followed by almonds, apples, onions and pears (high FODMAP foods).
Additionally, overall diet adherence rates were statistically comparable, and patients reported no adverse effects related to the intervention.
Patients on the individualized diet showed significantly greater increases in IBS Global Improvement Scale (GIS) scores compared with those on the sham diet, which served as the primary endpoint. At 4 weeks, the mean difference in scores between groups was 0.86 (95% CI, 0.05-1.67), and at 8 weeks it was 1.22 (95% CI, 0.22-2.22).
Both groups showed significant improvements in IBS Symptom Severity Scale scores, but those on the individualized diet showed significantly greater reductions relative to the sham diet. At 4 weeks, the mean difference in score change from baseline between groups was –61.78 (95% CI, –4.43 to –119.14), and at 8 weeks it was –66.42 (95% CI, –5.75 to –127.09).
Both groups experienced statistically comparable changes in mean IBS Adequate Relief and quality of life scores.
Further analysis of plasma samples from strong responders showed that reduced levels of a single protein (neutrophil elastase) were associated with reduced symptoms.
The investigators concluded that this study provides novel data supporting the strategy of using leukocyte activation testing to develop individualized diets for IBS.
“If these intriguing results can be replicated in larger and more diverse samples they can provide insight into another way to treat a condition that can often be very frustrating,” Ali said in the press release. “It can be debilitating and patients are often looking for dietary approaches to it.” – by Adam Leitenberger
Disclosures: The researchers report no relevant financial disclosures.
Perspective
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William D. Chey, MD
Several companies have marketed leukocyte activation tests or mediator release tests for some time, based on the idea that you can identify patients with sensitivities through activation of immune cells after exposure to different types of food antigens. However, up until this point, the use and marketing of these tests have been founded only on some animal data, intuitive reasoning, and even desperation. Because there is no clear explanation for their symptoms, and often patients associate their symptoms with eating a meal, many patients with IBS are attracted to the hypothesis that a blood or stool test can identify food sensitivities and allow the development of a tailored diet based on the test results in the hopes of achieving symptom improvement.
This mixture of faith, belief and desperation has really been driving the behavior of both patients and providers, so this is an exciting study because it actually lends some evidence to the notion that these tests might be of benefit. However, I emphasize the word “might,” because the reality of this study is that it’s small, it’s from a single center, and some of their outcomes show benefits while others don’t.
There have certainly been small studies of interventions for IBS that appeared beneficial in some outcomes and not as beneficial in others that have turned out to not be helpful, but the opposite is also true. So, to me, the take home message here is that these tests might work, but we clearly need further research from large, well-designed studies to validate whether leukocyte activation testing is beneficial in IBS patients or not. This is a great start, it’s incredibly encouraging, but by no means does this provide a definitive answer, and in fairness to the authors, they don’t suggest it provides a definitive answer either. I think they’re appropriately circumspect regarding what they found, what it means, and what needs to get done going forward.
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