Elimination diets guided by leukocyte activation tests reduced symptoms in patients with irritable bowel syndrome (IBS) in a parallel-group, double-blind, randomized controlled trial.

Study participants were randomized to a 4-week diet with individualized guidance to either eliminate foods with positive assay results and to allow foods with negative assay results (intervention group), or to eliminate foods with negative assay results and allow foods with positive assay results (comparison group). The 29 patients in the intervention group had significantly greater increases in mean IBS Global Improvement Scale scores at 4 weeks and 8 weeks vs. the 29 patients in the comparison group (mean between-group differences, 0.86 and 1.22 points, respectively), reported Ather Ali, ND, of Yale University, New Haven, Conn., and colleagues (BMJ Open Gastro. 2017;0:e000164. doi: 10.1136/bmjgast-2017-000164 ).

Mean IBS Symptom Severity Scale Score reductions were also significantly greater in the intervention group at 4 and 8 weeks (mean between-group differences, –61.78 and –66.42, respectively), the investigators wrote.

Improvements were seen in IBS Adequate Relief and Quality of Life scores in the intervention group, but the differences between the groups were not statistically significant. No adverse effects related to the intervention were reported, they said.

Of note, strong responders in the intervention group experienced significant reductions in neutrophil elastase.

IBS is a prevalent, costly, and often disabling condition, but assessing food intolerance in clinical practice is challenging, the investigators said, adding that while a number of commercially available blood tests claim to diagnose food intolerance – including leukocyte activation tests, which are among the most widely used for this purpose – no rigorous studies of the tests have been published.

For the current study, adults aged 18-75 years who met Rome III criteria for any subtype of IBS and had active symptoms were enrolled from an academic health center in Connecticut. The leukocyte activation test was used to culture peripheral blood leukocytes with standardized individual food extracts, producing either a positive or negative result, which then guided the food elimination.

The findings demonstrate that “a diet guided by leukocyte activation testing results in demonstrable clinical improvement in IBS,” they wrote, noting that dietary changes based on a leukocyte activation test may be less restrictive than those associated with a low–fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (low FODMAPs) diet (which has also shown promise as “an efficacious, although burdensome, dietary intervention for IBS”), and may result in better long-term adherence.

“These clinical results, associated with a reduction in plasma neutrophil elastase, have implication for better understanding the role of food intolerance and the pathophysiology of IBS,” they said, adding that “future studies, ideally multisite and in larger samples, can assess comparative effects of other dietary interventions in IBS, the effects of restricting specific foods, and whether dietary changes guided by leukocyte activation testing affect other conditions.”

Cell Science Systems funded the study. The authors reported having no disclosures.


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