Reading Professor Jonathan Brostoff’s riposte to my article, ‘Allergy: A Clash of Cultures’ (Foods Matter, June 2003 and August 2003), I was reminded of the rather exciting public debate in Oxford that we both took part in several years ago. We did not agree, of course, but I like to think we both took something away from the experience. Debate is valuable if it results in change.

Professor Brostoff makes the important point that an acute hypersensitivity reaction to food substances can take place in the lining of the gut without any evidence in blood or skin tests. I was not familiar with the paper he quoted and I thank him for drawing my attention to it. I did read, however, that the study group had responded positively to double-blind placebo-controlled food challenges, 6/14 had lifelong food hypersensitivities, 11/14 had had allergies in childhood and 7 were atopic; in other words they were a proven allergic group.(Lin et al. 2002) Food challenges, in which the food is concealed in a capsule that is swallowed by the patient, are probably the nearest we get to a gold standard for food allergy, yet strangely they do not seem to have been conducted very often. Hunter’s group in Cambridge advocate a minimum intake of 100g daily for four days to identify a ‘slow’ intolerance that may not have been mediated by any classical immunological mechanism (Parker et al. 1995). No challenges were carried out in the Oxford study (Nanda et al. 1989). Elimination diets were effective in over 50% of IBS patients from those two groups, but other groups using similar methodology could not reproduce anywhere near the same response rates (Farah et al. 1985;McKee, Prior, & Whorwell 1987). If we assume that there were not crucial differences in the methodology among these studies, the different results may relate more to the success of different groups in recruiting the patients expectation and belief.

Expectation and belief plays an enormous role in the therapeutic response to IBS, so much so that they often confound the testing of new drugs. Indeed when patients faith is recruited by hypnosis or psychotherapy, 80% of them improve (Guthrie et al. 1991;Whorwell, Prior, & Faraghar 1984). And as Ian Wickramasekere has pointed out using biofeedback techniques, the convincing demonstration of an abnormal physiological response coupled with a logical treatment that rectifies it, recruits faith and promotes recovery (Wickramasekere 1998). Food allergy is a powerful focus of belief. Most of us tend to assume that we have eaten something that has disagreed with us when we get gut symptoms. So if our prejudice is confirmed by food challenges and elimination diets, then recovery rates will be very good, irrespective of whether or not there is any objective evidence of food allergy. There is nothing inherently wrong with this, in my opinion. It is essentially the effect of ‘healing’ and modern medicine would probably achieve better effectiveness and patient satisfaction by harnessing the power of healing to the efficacy of the specific treatment.

Unfortunately, western, evidence-based, scientific medicine can seem to dismiss recruitment of belief and expectation as quackery with all the negative connotations of deception and exploitation. So what may be a very effective healing response has to be dressed up as scientific fact in order to pass muster. The Pimental studies that Professor Brostoff refers to are a case in point (Pimental, Chow, & Lin 2000). They hinge on the assumption that a double peak of breath hydrogen following a drink of the unabsorbable sugar, lactulose, indicates overgrowth of fermentative bacteria in the small intestine. That assumption is false. Studies in which a radio-labelled dose of lactulose is tracked down the small intestine by means of a gamma camera shows that both peaks are produced when the sugar enters the colon (Riordan 2001). Reinforced with convincing pseudoscience, it is not surprising that administration of antibiotics makes people feel better. Another example is the candida hypothesis, which not even the Cambridge group could find the evidence to support (Middleton, Coley, & Hunter 1992) .

Professor Brostoff evokes the philosopher, Karl Popper, to criticize psychological theories of IBS on the grounds that they cannot be proved or disproved (Popper 1934). I don’t really think that is a fair comment. Not only do patients with IBS tend to have more anxiety and depression than healthy people or patients with organic gut diseases (Dinan et al. 1991;Whitehead, Palsson, & Jones 2002) and show hormonal evidence of biological stress responses , there is a strong association between IBS and life situations causing threat (Bennett & Kellow 2002) and as I described in my article, prospective studies have shown that anxiety, depression and threatening life events at the time of an an attack of gastroenteritis are important predictors of IBS. By application of the same Popperian logic, hypotheses implicating ‘candidiasis’ and ‘abnormal bugs’ pale by comparison. In any case, doesn’t the notion of allergy as the major cause of IBS appear vague and diffuse when so many different theories and diets are recruited to support it?

But it is not my intention to score points in an ongoing and probably never-ending debate, it is to find a way in which our perspectives, each based on extensive clinical experience, can come together. In recent years, there has been an ever more rapidly accumulating body of evidence showing that emotional stress can trigger allergic rhinitis, atopic eczema and gastrointestinal allergies (Frieri 2003). Stress releases the cytokines that induce inflammatory responses, it activates the sympathetic nervous system and it can reduce the activity of the hypothalamo- pituitary adrenal axis. All of these changes excite immune responses, increasing mast cells, enteroendocrine cells and all the other immune components referred to by Professor Brostoff. It also increases the sensitivity and reactivity of the gut. So it stands to reason that things that cause alarm, like the bells in Professor Beinenstock’s experiment (MacQueen et al. 1989), would excite allergic responses while anything that recruits the confidence and trust of the patient and induces a state of relaxation might well damp down the immune response. This would explain why many patients report that intolerance of certain foods can wax and wane according to how they are feeling in themselves.

I would like to set the scene for rapprochement. There is not only a very large body of evidence that supports the importance of psychological factors in IBS, but there is also substantial data that supports the involvement of food allergy/ intolerance. It is not a case of either one or the other; we need to understand how both food and mood might interact to bring about the patients symptoms. We all have the potential to develop allergy, but whether that potential is realized and whether we suffer from mild or severe symptoms depends in part on exposure and in part on how we feel. Similarly treatment should not just be seen as a case of putting people on an elimination diet, it also requires us to address what has happened in the person’s life to make him ill. In suggesting this, I do not seek to blame the patients or their parents for the way they are, but more to provide a framework of understanding that would allow the patient to seek the best route to recovery. This is truly an area where different specialists can achieve more for their patients by working together.

References

Bennett, E. & Kellow, J. E. 2002, "Relations between chronic stress and bowel symptoms," in Irritable Bowel Syndrome: Diagnosis and Management, M. Camilleri & R. Spiller, eds., W.B.Saunders, Edinburgh, pp. 27-36.

Dinan, T. G., O'Keane, V., O'Boyle, C., Chua, A., & Keeling, P. W. 1991, "A comparison of the mental status, personality profiles and life events of patients with irritable bowel syndrome and peptic ulcer disease", Acta Psychiatrica Scandinavica, vol. 84, pp. 26-28.

Farah, D. A., Calder, I., Benson, L., & Mackenzie, J. F. 1985, "Specific food intolerance:its place as a cause of gastrointestinal symptoms.", Gut, vol. 26, pp. 164-168.

Frieri, M. 2003, "Neuroimmunology and inflammation: implications for therapy of allergic and autoimmune diseases", Annals of Allergy, Asthma and Immunology, vol. 90, pp. 34-40.

Guthrie, E. A., Creed, F., Dawson, D., & Tomenson, B. A. 1991, "A controlled trial of psychological treatment for the irritable bowel syndrome", Gastroenterology, vol. 100, pp. 450-457.

Lin, X. P., Magnusson, J., Ahlstedt, S., Dahlman-Hoglund, A., Hanson, L. A., Magnusson, O., Bengtsson, U., & Telemo, E. 2002, "Local allergic reaction in food-hypersentive adults despite a lack of systemic food-specific IgE", Journal of Allergy and Clinical Immunology, vol. 109, pp. 879-887.

MacQueen, C., Marshall, J., Purdue, M., Siegel, S., & Bienenstock, J. 1989, "Pavlovian conditioning of rat mucosal mast cells to secrete mast cell protease", Science, vol. 243, pp. 83-85.

McKee, A. M., Prior, A., & Whorwell, P. J. 1987, "Exclusion Diets in irritable Bowel Syndrome: Are they worthwhile?", Journal of Clinical Gastroenterology, vol. 9, pp. 526-528.

Middleton, S. J., Coley, A., & Hunter, J. O. 1992, "The role of faecal candida albicans in the pathogenesis of food-intolerant irritable bowel syndrome", Postgraduate Medical Journal, vol. 68, pp. 453-454.

Nanda, R., James, R., Smith, H., Dudley, C. R. K., & Jewell, D. P. 1989, "Food Intolerance and the irritable Bowel", Gut, vol. 30, pp. 1099-1104.

Parker, T. J., Naylor, S. J., Riordan, A. M., & Hunter, J. O. 1995, "Management of patients with food intolerance in irritable bowel syndrome: the development and us of an exclusion diet.", Journal of Human Nutrition and Dietetics, vol. 8, pp. 159-166.

Pimental, M., Chow, E. J., & Lin, H. C. 2000, "Eradication of Small Intestinal Bacterial Overgrowth reduces symptoms of Irritable Bowel Syndrome", American Journal of Gastroenterology, vol. 95, pp. 3503-3506.

Popper, K. 1934, The Logic of Scientific Discovery Hutchinson Press.

Riordan, S. M. 2001, "Small Intestinal Bacterial Overgrowth and the Irritable Bowel Syndrome", American Journal of Gastroenterology, vol. 96, pp. 2506-2507.

Whitehead, W. E., Palsson, O., & Jones, K. R. 2002, "Systematic Review of the Comorbidity of Irritable Bowel Syndrome with other disorders: What are the causes and implications?", Gastroenterology, vol. 122, no. 4, pp. 1140-1156.

Whorwell, P. J., Prior, A., & Faraghar, E. B. Controlled trial of hypnotherapy in the treatment of severe refractory irritable bowel syndrome. Lancet 2, 1232-1234. 1984.

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Wickramasekere, I. Secrets kept from the mind but not the body or behaviour: the unsolved problems of identifying and treating somatisation and psychophysiological disease. Biofeedback and Self-Regulation 14, 81-132. 1998.

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