An exploratory comparative investigation of Food Allergy/Sensitivity Testing in IBS (The FAST Study): A comparison between various laboratory methods and an elimination diet
Introduction
Adverse food reactions are a broad category whose symptoms can be associated with an immune mediated response, either IgE or non-IgE mediated, called food allergy (FA), or non-immune mediated called food intolerance (FI) [1]. Non-IgE mediated FAs (NIMFAs) usually produce delayed reactions that are not life-threatening and are associated with less severe or long-term symptom development such as digestive difficulties or joint stiffness [2].
The gold standard used to confirm a FA is through an elimination/challenge (E/C) diet under controlled circumstances. Many variants of the E/C diet exist [3], [4]. The E/C diet involves the elimination of all major potential allergens for a period of between three to six weeks [4]. The challenge phase, which can be blinded, involves consuming several servings of the suspected food for one day and monitoring for signs and symptoms for up to 72 h. If a food does elicit a reaction, the food is avoided; if no reaction is noted, the food can be consumed.
A high degree of compliance and commitment is required to adhere to an E/C diet and may take months to complete. Efforts to accurately identify NIMFAs and provide patients with specific treatment strategies sooner have spawned the development of more objective and achievable methods to identify NIMFAs [5]. Some of these methods include cytotoxic assays, serum IgG antibody assessment, electrodermal screening (EDS) and applied kinesiology. Evidence for and acceptance of these methods is variable and limited [5], [6], [7].
Our current understanding of irritable bowel syndrome (IBS) suggests that FAs may indeed play a role in IBS symptomatology [8], [9]. A high percentage of IBS sufferers report symptom exacerbation after the ingestion of various food(s) [10], [11]. However, many are not able to pinpoint the specific food(s) or adhere to an E/C diet [11]. Theoretically, increased gastrointestinal (GI) barrier permeability may lead to an increased activation of the immune system as part of the IBS pathogenesis [12]. Studies investigating NIMFA testing in IBS sufferers have found an improvement through the elimination of food(s) identified on these tests [13], [14], [15], [16], [17], [18], [19], [20]. However, no study has compared the predictability of each method to the results of an E/C diet [5]. An understanding of the relative agreement between these tests may help patients and practitioners make better decisions around how to best investigate NIMFAs for IBS.
The objective of this study was to explore whether NIMFA test methods would be helpful in predicting whether foods would elicit an exacerbation of symptoms in IBS sufferers.
Section snippets
Methods
This was a correlative, hypothesis generating study conducted from February 27, 2013 to April 24, 2013. The study was funded by a grant from the Canadian CAM Research Fund through the Canadian Interdisciplinary Network for Complementary and Alternative Medicine Research and registered at ClinicalTrials.gov (NCT01791621).
Recruiting occurred between January–February 2013, using online advertisements through the Canadian College of Naturopathic Medicine's (CCNM) website and social media channels;
Results
Participants were recruited between January 9, 2013 and February 14, 2013. Interested participants were screened for the inclusion criteria and their commitment to following an E/C diet. Participants were initially excluded because they failed to meet the inclusion criteria or were not prepared to commit to the study. Supplementary Data Figure 1 provides the details of the selection process. Table 1 summarizes the characteristics of the participants. A 90% compliance threshold was established
Discussion
This is the first study to examine the correlation between the results from several different NIMFA tests with GI symptoms in IBS sufferers after a standardized 4 week elimination diet. The results of our pilot study suggest that these laboratory tests may not be helpful in the identification of the specific foods that exacerbate the GI symptoms in IBS sufferers. The immune based evaluation of the NIMFAs demonstrated the lowest sensitivity. The testing method with the highest sensitivity was
Conclusion
None of the NIMFA tests evaluated in this study were found to be diagnostically predictive in the identification of specific foods that exacerbate the gastrointestinal symptoms in our small sample of IBS sufferers. Diet would appear to have a role in IBS symptomatology, since an elimination diet was found to reduce symptom severity. Further investigation into the role of diet and food choices in IBS is warranted.
Conflict of interest
The authors have no conflict of interest to declare.
Acknowledgments
We thank our participants for their participation and dedication to the study, Hind Hussien, BSc, MSc, CMLTO, CSMLS for her amazing laboratory support in obtaining all of the blood samples for this study, CCNM and IHC for the study consultation space, and Jonathan Prousky, MSc, ND, Chief Naturopathic Medical Officer, The Canadian College of Naturopathic Medicine for assistance in collating lab results. This study was funded by a grant from the Canadian CAM Research Fund through the Canadian
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