FOOD ALLERGY: TRIALS INVOLVING IBS- SEVERAL MAJOR DRAWBACKS TO THIS STUDY
Unfortunately, there are several major drawbacks to this study. Firstly, the number of patients involved was very small, and they were probably what doctors call ‘a highly selected group’: that is to say, they were not representative of IBS patients as a whole, for reasons that have already been discussed. Secondly, 59 per cent of the patients studied refused to undertake a full elimination diet, and according to the authors ‘wheat was not excluded in all these patients’. Thirdly, and most seriously, the method used for double-blind testing was highly questionable. In order to disguise the taste of the foods being tested, the Manchester team used dried, powdered foods and placed them in gelatine capsules. It has been calculated that a single tablespoonful of food would fill 12 such capsules, yet only one capsule was used for each test. It is widely accepted, by orthodox and unorthodox doctors alike, that food intolerance reactions do not occur with such small amounts of food. Food allergy reactions can, of course, and the test procedure was probably designed with these sort of reactions in mind. It is significant that the three patients who showed consistent positive reactions also had a range of atopic symptoms – asthma, eczema, urticaria or hay-fever. In other words, the double-blind test was probably detecting those with IgE-mediated allergic reactions to food and missing others with food intolerance. As the authors themselves admit ‘… even patients with clear evidence of immunologically mediated sensitivity may not react every time they are exposed, particularly if the dose is limited.’
Another trial of IBS patients, carried out two years later by a different group of doctors, produced similar results. In this study, only three out of 49 patients were found to be food intolerant. Unfortunately, this study followed a similar procedure to that of the Manchester group – wheat and citrus fruits were not excluded, and capsules were used for double-blind testing.
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