It is accepted that a washout period would be ideal but this would have extended the study inordinately. Also, it was considered that by omitting the last three days of each week of consumption of a food, the carry-over effect was minimized. This meant that during the assessment period no new food had been consumed within 96 h. During a food challenge week the patient was asked to eat the particular food freely throughout the week.

Throughout this period diary cards were kept and completed on a daily basis and if problems arose or inane food challenge caused a reaction the patient contacted the research nurse who instructed them to stop and return to the elimination diet until the next challenge was due. After the full 14 weeks of dietary manipulation, the patients were assessed by a clinician and a research nurse, the diary cards were examined and compliance discussed. The end of this period represented the end of the study and a global assessment was made as to whether these were associated with non-compliance.

The clinical symptoms following food challenge were analyzed by dividing the data into two classes: ‘negative’ foods where the Alcat Test score was 1%-9% and ‘positive’ foods where the change was greater than 13%. As a result of analyzing symptom scores of 120 separate double-blind food challenges using an analysis of variance, 43 out of 60 positive foods on the Alcat Test produced symptoms whereas 11 out of 60 negative foods produced symptoms, which is statistically significant (p <=0.5). The symptom scores were significantly higher in the positive food group (p=0.02) and this group also needed more drugs than those weeks where they were eating foods which were negative on the Alcat Test (p=0.01). A wide range of drugs were used for these patients but it was not considered necessary to make a long list of the different of treatment that they received, but included were fibre products,- anticholinergic, anti-inflammatory and anti-spasmodic agents plus, in many instances, nystatin. It is also interesting to note that most patients were able to continue their challenge for a full week. In those patients (n=5 ) who stopped their challenges before the end of the full week ( nine food challenges ), the majority (eight out of nine ) were positive on the Alcat Test. Thus the Alcat Test classed as positive or negative and, omitting borderline values (9%-13%), was associated with an appropriate symptom score during blind challenge in 72% of positive foods and 81% of negative foods. The 9%-13% has been considered borderline based empirical on results from the Alcat Test accumulated so far. This again was a comparison between the healthy volunteers from the Miami football club and those attending Dr Sandberg’s clinic [6, 7]. Considering individual symptoms as shown in Table 2, there is a significant increase in symptom score following relevant challenges for all symptoms (p < 0.05). There was one exception-Backache, which was not improved but also confined to three patients so it was considered insufficient to record. All these sums were aggregated from the last three days of challenge versus the last three days of elimination. Means are not recorded because like most diary card keeping, the results skewed. At the end of the further six week elimination period, ten out of the 20 (50%) patients had maintained improvement and were still symptom free. Though we have no statistical evidence of this we consider the most likely cause of failure in 50% of the patients was due to lack of compliance. The diary cards in several indicated this.

TABLE 2. Results comparing three days diary cards accumulated scores. Food challenge for three days versus three days during elimination diet

A recent review of treatment for IBS Klein [8] concluded that “not a single study offers convincing evidence that any therapy is effective in treating the IBS symptom complex”. Yet, in none of the 43 trials reviewed was diet considered an important factor. There is now increasing evidence that diet should be considered to be important in this syndrome. The work of Hunter’s group [3] shows a definite link and a recent report by Nanda has also described good responses to food elimination diet in IBS with a 48% overall success rate during the 14 month follow-up period [4]. If this period could be cut short, compliance would improve and the overall success rate might increase. The problem of unusual foods causing reactions still remains, perhaps accounting for some of the failures in the Oxford series.

The underlying mechanism of the Alcat Test is not understood. Lymphocyte activation to food proteins has been shown with beta-lactoglobulin [9, 10] and rice protein [11], although others have not been able to confirm the clinical relevance of these results [12, 13]. Lymphokine production, especially leukocyte migration inhibition factor (LIF) has also been investigated for the diagnosis of food intolerance and good clinical correlations with positive tests have been shown [14]. However, the cell culture time has been considerably longer than the 90 min used in are experiments. The mechanism of change in cell size in the Alcat Test awaits elucidation. Certainly damage to cells when in contact with foreign protein has been demonstrated by other workers [13-15]. Autocytotoxic phenomenon (ACT) is seen in bronchial asthma and is not always IgE mediated or the consequence of a priming action by antigens and antibody.

The direct toxic effect of food antigens on specific cells may be a reassuring action to protect the immune system from infancy. However, some food lectins contribute to cell damage at the level of the gastro-intestinal tract [18] and may even cause cell death indirectly by the mechanisms that are unclear [5, 16]. Furthermore, many foods contain known pharmacologically active or toxic chemicals which may directly act on cells [16, 19].

Whichever mechanism pertains, whether of actively toxic agents, immunologically driven or not, and identified by the final common pathway of cellular change, swelling, vacuolation, degranulation or destruction, the Alcat Test provides useful results as the consequence of this final common pathway.

The data from are trial and others [3, 4] clearly show that a proportion of IBS patients have a food sensitivity and an exaggerated colonic motility response to a stimulus that has no psychological significance [14]. It is therefore unreasonable to consider that psychopathology is the main cause of the disorder [1].

If our results are confirmed in a larger series of patients, then clearly this test would be useful adjunct in a busy gastro-enterology clinic where a considerable proportion of patients will be suffering from IBS. The development of ‘tailor-made diets’ designed for each patient must be better than the hit or miss methods currently available.