Food Elimination Based on IgG Antibodies Helpful in Irritable Bowel Syndrome

Food Elimination Based on IgG Antibodies Helpful in Irritable Bowel Syndrome

News Author: Laurie Barclay, MD

CME Author: Désirée Lie, MD, MSEd

Sept. 16, 2004 — In irritable bowel syndrome (IBS), food elimination based on IgG antibodies reduced the symptom score by 26% in fully compliant patients, according to the results of a randomized, controlled trial study published in the October issue of Gut.

"Patients with irritable bowel syndrome (IBS) often feel they have some form of dietary intolerance and frequently try exclusion diets," write W. Atkinson, MD, from the University Hospital of South Manchester in the U.K., and colleagues. "Tests attempting to predict food sensitivity in IBS have been disappointing but none has utilised IgG antibodies."

The authors suggest that adverse reactions to food in patients with IBS might be caused by some form of immunologic mechanism other than dietary allergy, particularly one mediated by IgG antibodies.

In this study, 150 outpatients with IBS were randomized to receive, for three months, either a diet (the "true diet") excluding all foods to which they had IgG antibodies based on enzyme-linked immunosorbent assay (ELISA) test or a "sham diet" excluding the same number of foods but not those to which they had antibodies. Primary outcome measures were change in IBS symptom severity and global rating scores, whereas secondary outcomes were noncolonic symptomatology, quality of life (QOL), and anxiety-depression. Analysis was based on intent-to-treat using a generalized linear model.

After 12 weeks, there was a 10% greater reduction in symptom score in the true diet group than in the sham diet group (mean difference, 39; 95% confidence interval [CI], 5 to 72); P = .02). In fully compliant patients, reduction in symptom score was 26% (mean difference, 98; 95% CI, 52 to 144; P < .001).

As a whole, the true diet group also had significant improvements in global rating (P = .048; number needed-to-treat [NNT], 9). These improvements were even more pronounced in compliant patients (P = .006; NNT, 2.5). The NNT for each group is considerably better than the NNT of 17 achieved after three months of treatment with tegaserod, a drug that has been recently licensed for use in IBS.

The true diet group also fared better than did the sham diet group in all other outcomes. In the true diet group, relaxing the diet led to a 24% greater deterioration in symptoms (difference, 52; 95% CI, 18 to 88; P = .003).

"Food elimination based on IgG antibodies may be effective in reducing IBS symptoms and is worthy of further biomedical research," the authors write. "Many patients with IBS would prefer a dietary solution to their problem rather than having to take medication, and the economic benefits of this approach to health services are obvious. It is well known that patients expend large sums of money on a variety of unsubstantiated tests in a vain attempt to identify dietary intolerances."

Gut. 2004;53:1459-1464

Medscape Medical News 2004. © 2004 Medscape

http://www.medscape.com/viewarticle/489349

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