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Food Intolerance and Chronic Illnesses

by John Graham and Mark Varey(more info)

listed in nutrition, originally published in issue 38 - March 1999

Intolerance to food has been implicated in playing a role in a wide spectrum of chronic illnesses; however, much of the evidence gathered to date has been from anecdotal clinical case studies, rather than large patient research studies.

Historical Introduction

York Nutritional Laboratory (YNL) had been providing services for GPs and other practitioners for the detection of the adverse reaction of foods since 1982. The original cytotoxic tests conducted by the laboratory required the practitioner to supply a full serum sample (10 ml) for investigations which would identify the foods that were causing problems for the patient. It was known that cytotoxic testing was subjective, although in the hands of a skilled technician the results were found to be successful. There was, however, always a concern about the reproducibility of such tests.

After much consideration it became a straight choice between automated variations of the cytotoxic test or the ELISA (enzyme-linked immunosorbent assay). The ELISA was chosen because it is a proven technique, which has been shown to be accurate, specific and reproducible. The method also had the practical advantage of requiring only a small amount of blood (as little as 50 microlitres) that could be obtained from a finger prick of blood, for instance. This simplification was considered to be of particular relevance to those practitioners who were unable or unwilling to draw blood from patients.

The Argument for a Patient Study

The laboratory had conducted some 22,000 tests over the years for medical practitioners; it was decided to be desirable to validate the results, and for the first time gain a significant level of patient response. The laboratory had read much evidence over the years regarding the important implication of food intolerance for those with chronic illnesses, but in most studies the common problem had always been that relatively small numbers of patients were involved, which was considered to be unsatisfactory from a scientific viewpoint.

Discussions with medical doctors and scientists at the University of York confirmed the value of carrying out a large-scale survey of patients. It was, therefore, decided to conduct a postal survey asking for information from those patients who had previously contacted the laboratory in order to take the ELISA test.

It was estimated that in order to be meaningful it would be necessary to have in the order of 250-300 responses so that a range of ages and the main chronic illnesses could be usefully assessed. It was decided to conduct a survey of all patients from within the UK taking the test in a three-month period, and questionnaires were in all cases posted four weeks after the patient had received the results of the test from the laboratory. The overall number of responses to the questionnaire was surprising but encouragingly high: 463 responses from a total universe of 882 patients. For a postal survey this was an unusually high level of response of 52.5%, which was partly encouraged by a promised payment of £1.50 to two allergy charities for each questionnaire returned and partly by a follow-up letter to non-respondents. (The payment was subsequently made to Action against Allergy and the Hyperactive Children's Support Group.) The last responses were collected in August 1998.

Research Objectives

YNL wanted to learn answers to the following questions:

1 What were the main conditions affecting patients?

2 Which were the main offending foods?

3 What did patients actually do with the results as they obtained them?

4 How much improvement did they experience?

5 How quickly, if at all, did they start to feel better?

6 Did certain groups achieve better success rates than others?

7 Did there exist any differences between those who rigidly adhered to diets compared with those who made limited efforts?

8 How would patients assess the overall value of the service?

9 Were there any significant differences between different age and gender groups?

By gaining a significant level of response it was hoped that information would be obtained which would then be helpful both to future patients and practitioners. A proprietary programme (SNAP 4) for inputting and measuring the responses was used, which meant that all the responses could be cross-tabulated for detailed analysis purposes, and in order that the statistical validity of the results could be established.

The advice of a medical practitioner (Dr M Matthews) was sought to ensure correct categorisation of the results. The conditions reported by the patients, in their own words, were broken down into six main categories.

Key results

The most common conditions reported by the patients were as shown in Table 1.

Table 1:Key Results

 Medical condition








No response


Patients'own words

IBS, diarrhoea,bloatedness,
sickness, cramps

asthma, breathing difficulties, sinusitis

headaches, migraines,tension

hives, eczema,urticaria, rashes, rosacaea

arthritis, fibromyalgia

depression, anxiety,fatigue, panic attack

heart conditions ME,MS, hair loss



% responses









111.9% *

* Some patients disclosed more than one condition.

The main symptoms reported were invariably the so-called chronic, and often intractable, diseases. Respondents were asked to reply using their own words. They reported a wide range of conditions including headaches, migraines, lethargy, skin rashes, stomach cramps, IBS, ulcerative colitis, rhinitis, arthritis, asthma, ME, being overweight as well as being depressed. It was quite evident that stomach and bowel problems dominated with 2 out of 5 people reporting these as being their main problem. Similarly it was noticeable that a relatively small number of patients in the "other" category reported difficult or more acute conditions such as heart problems.

Patients were asked to state how long the condition had concerned them. The results indicated that, in the main, respondents had experienced their symptoms for many years:

0-1 months        0%
1-6 months     5.0%
7-35 months   24.4%
3-10 years     28.3%
10 years plus 32.2%
NR                    9.9%
Total            100.0%

• 61% had suffered for three years or more and the largest single group was the nearly one third who had suffered from their illness for more than ten years. In many cases these patients reported that they had had the symptoms for nearly all their lives. Many patients were contacting YNL for help after many years suffering from intractable conditions. A large number also reported that taking the test was "a last resort".

• YNL carried out a simultaneous analysis to learn how often patients had reacted to different foods. This showed that patients had on average a strong reaction to 4.7 foods, and a significant reaction to a further 8 foods. [Figure 1]

Food Intolerances

• The top ten most common offenders were cow's milk and derived products (inc. cheese and yoghurt), wheat, yeast, goat's milk, blackcurrant, kidney beans, eggs, prawn, sunflower seed and soya.

• A cross-check on the degree of improvement obtained showed a significantly higher rate of improvement when the GP or adviser became involved compared with when the patient relied on the guidebook alone. A clear majority of patients reported the highest improvement in condition when the doctor or adviser became involved.

• When asked how much improvement they had obtained, 67% of the patients involved reported scores of 3, 4 or 5 out of a potential score of 5. Nearly half of the sample (48%) gave scores of 4 and 5, which indicates a relatively high degree of perceived improvement.

• More than half (58%) of the respondents reported that they had benefited within as few as 20 days. This increased to 72% who felt that they had benefited within 60 days. As these were predominantly patients with illnesses that had endured for several years, this can be considered to be a useful record of success.

• 70% of patients responding were female whilst 29% were male. This corresponded fairly well with the proportions taking the test which were 66% female and 34% male. The range of ages was between three months and 80 years old. Men tended on average to take the test later in life than women with the average age of men being 58 years whilst the average age for women was 52. 73% of all patients were between 30 and 70 years old. The numbers of boys and girls below the ages of 9 years was equal, and 15 such children were involved. The youngest child was a 3-month-old baby with multiple allergies and symptoms.

• One of the main conclusions of the survey is that the majority of patients taking the test and altering their diet reported that they had found significant improvements in their condition. Sometimes these improvements were spectacular with one fifth of all patients giving the highest score possible.

• The degree of benefit was found to be particularly strong when patients reported rigorously altering their diet, though benefit was still noted when diet was only moderately altered. Improvements were noted in around 72% of cases, and 86% of those responding stated that they would recommend, or already had recommended YNL to other people.

• Those patients who had consulted with their doctor or medical adviser also reported considerably more benefit than those who did not.

General Conclusions

A significant proportion of those suffering from a wide range of apparently intractable chronic illnesses appeared able to obtain significant symptom relief by testing for delayed food allergies and altering their diet in an appropriate manner. Those consulting with their practitioner or health adviser obtained the best results, and around 70% to 75% of respondents reported significant improvement in their condition.

The overall findings of the research work have encouraged further research work to be carried out. This is at two levels:

1 An in-depth study whereby Dr M. Matthews and the author of this report will be further analysing the responses from the gastrointestinal, dermatological and neurological cases. This will be reported in Issue 42 (July '99) of Positive Health.

2 York Nutritional Laboratory intends to carry out further research and is establishing a partner relationship with two academic organisations in order that full clinical trials may be conducted.


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About John Graham and Mark Varey

John Graham BSc (Hons), DipM MCIM is Commercial Director and Mark Varey Technical Director of York Nutritional Laboratory.  John Graham has a B.Sc.(Hons) degree from Aston University and more recently a masters degree in business administration from Leeds Business School. Prior to joining the laboratory he carried out previous research studies in other fields.

Mark Varey MIScT is a food technologist with more than 16 years' experience of laboratory testing for food allergies and sensitivities.

York Nutritional Laboratory is one of Europe's leaders in testing for classical allergies and food intolerances. The laboratory has experience in working with medical practitioners for over 16 years in the UK.  More than 24000 patients with a wide range of chronic illnesses have been assisted within that period. York Nutritional Laboratory now called YorkTest Laboratories, may be contacted on Tel: 0800 074 6185 / +44 (0)1904 410 410;

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