Add as bookmark

Testing for Food Sensitivity

by Dr PJ Fell Lond.(more info)

listed in allergy testing, originally published in issue 28 - May 1998

Whether one believes in evolution or creation it would be misguided to think that the great variety and very efficient mechanisms for detoxifying chemicals in the body were put in place because man would be clever enough in the twentieth century to discover a vast array of new chemicals called drugs. No, they have been in place for millions of years to enable man to adapt to the environment, eat food, extract the nutrition from it without being poisoned by the chemicals which naturally occur in all food – the xenobiotics. This has been extended somewhat by the food industry which adds more chemicals or by industry which has polluted the environment, but these represent only a small proportion of the daily chemical load processed by the body.

The Alcat Process Chart

An individual may vary as much as threefold in their ability to detoxify at various times and under changing circumstances and different individuals vary several fold so there may be a rate difference detoxifying as much as eleven times between individuals. Thus one person may drink a cup of coffee after dinner and be happily asleep three hours later whereas another still suffering the effects of caffeine may still be awake in the early hours.

When food is put in the mouth the process of digestion begins and this consists of extraction of the nutritionally valuable products while at the same time resisting or neutralising the poisons which are an integral and natural part of food. Plants and animals also want to survive and not be eaten by hostile predators so whether it's the chemicals in plants or the toxins in fish or the protective coatings of progeny they are all there to resist being ingested and digested. While these processes are continuing in the gut they are in reality outside the body until they cross the gut wall and are absorbed into the animal, in this case the human. It is not surprising therefore that all along the gut wall from start to finish there are systems to enhance the absorption and utilisation of nutrients and others to resist or neutralise xenobiotics.

Alcat test equipment

Test Equipment

There are enzymes and hormones to degrade the toxins or modify them for quick elimination, there are proteins to bind on to them so they may be transported safely to the liver for detoxification and there are a host of different white cells manufacturing these, manufacturing local antibodies for defence and transporting toxins for elimination themselves. These white cells are often specific for certain molecules and in performing their tasks alter in size, and that alteration can be detected.

The main stay of detoxification is an enzyme system known as the cytochrome P450 system and this is versatile in the extreme detoxifying a wide range of chemical structures, but it has one drawback and that is it works at a set rate and cannot accelerate as concentrations of toxins increase. The result is the body may be overwhelmed acutely or chronically if a high intake of specific toxins occurs and it is this situation that leads to food sensitivity. It is not allergy, it is not necessarily permanent and it is not always the case that illness ensues. Consider alcohol which if imbibed too quickly or in too large an amount will lead to drunkenness, the next day to a toxic 'hangover' and the next day back to normal.

Some individuals who are susceptible to these xenobiotics may have symptoms varying from the mild to the severe and even to death. The symptoms may be acute or chronic – so diarrhoea, vomiting, headache, joint pain and skin irritation may be temporary or may develop into a continuing illness. Thus irritable bowel syndrome, migraine, rhinitis, urticaria (hives), wheezing and a host of other symptoms may lead the individual to associate food with their symptoms. In some instances the individual is quite clear as to what causes the problems, eliminates the food from their diet and suffers no more, perhaps occasionally or inadvertently ingesting it and experiencing the same symptoms as before. However, many people though suspicious that it is a food or foods causing the problem, cannot identify the likely candidates. It is even more difficult if it is a constituent or chemical or multiples of these in which case simple elimination techniques simply do not work. Compounding this is the fact that different substances cause problems with different times of onset, some in minutes others in days.

For some individuals the symptoms and severity are such that they ruin their lives; for others they are less but they still interfere with the individual's lifestyle or causes them at times to perform badly.

Feeling very tired after eating, having a low grade headache several days per week or waking stiff and fatigued may be vague in medical terms but they are nonetheless quite clear and debilitating to the patient. These can all be food related. Things become more serious when some of the syndromes become permanent, such as irritable bowel syndrome where the individual is either in great discomfort because the bowel will not move or faces the opposite situation of several painful bowel actions every day. Frequent migraine headaches or severe skin irritation and swelling, though not life threatening, are still to the patient serious and distressing. Thus food, while most of the time, giving the majority of us great pleasure, for a few it is the cause of great concern and ill health.

This is where some of the new laboratory tests help. I use one imported from the USA and provided by OATS Ltd and called the ALCAT test. I have had good results in many hundreds of patients over the past few years. There are several others providing similar information but essential to all of them is the correct interpretation and application to the specific medical conditions. The ALCAT test simply measures a change in the size of white cells after they have been incubated with individual foods, food constituents and food chemicals.The test ranks the foods etc. as a percentage shift from the control values giving the worst i.e. the highest percentage shift to the least reactive i.e. the lowest percentage shift. This is only the first step because the results are then fed into a computer database which identifies where those offending items can be found in the diet. Using it it is possible to quickly construct a tailor made elimination diet.

The next step is to ensure the elimination diet is nutritionally sound and if it is lacking, which dietary supplements will be necessary. It must then be followed for a period of not less than six weeks. Sometimes this time course needs to be longer depending on the frequency of symptoms. Some conditions such as angioedema (swelling of the face, lips and tongue) may be less frequent so an adequate time course must be allowed. Other conditions such as attention deficit disorder, where the food element may be only one component, also need other expert input if an assessment of improvement is to be made.

Once an improvement is noted by the patients, they then act as their own benchmark by reintroducing foods in a structured and controlled fashion ultimately ending up, hopefully, with a few foods identified and linked to their symptoms. It also enables the individual to have a socially acceptable diet which is enjoyable and free from what are often quite debilitating symptoms.

This test was initially applied to a group of patients in a double blind controlled study. The patients chosen were those where food might be implicated in their illness, migraine, urticaria, eczema and irritable bowel syndrome. The results were encouraging and showed the predictability of the test was statistically significant. Over 200 individual food challenges were conducted and there were approximately 30% false positives and 18% false negatives. The next series of patients were controlled more stringently and limited to irritable bowel syndrome only. They had all been symptomatic for 3 years and this publication was published in the Journal of Nutrition. The target symptoms, tiredness, bloating, number of motions, abdominal pain, headache and nausea were significantly different during the challenge period. A difference in score was statistically significant.[1]

There then followed a number of studies reported by other workers in other fields demonstrating the usefulness of this test.

Two carefully controlled studies by Dr Lene Hoj of Copenhagen showed excellent results. One study on 92 patients, highlighted the usefulness of the ALCAT test in predicting positive result with challenge, this time using chemicals, used as food additives and probably not via any immune mechanism. The test was shown to have a .96 efficiency.[2,3]

Another study in San Antonio on dieting supported by information on food sensitivities from ALCAT tests, showed a change in weight following an ALCAT diet.[4]

By the time this work was carried out in the 1990s we had noticed that in many of our patients being treated for food sensitivity with diets predicted by the ALCAT test there was a loss of weight as well as an alleviation of symptoms. This study embraced this observation and in a controlled fashion measured the weight loss and proved that this was a secondary beneficial effect. It opened up the possibility that some types of obesity might be treated by diets predicted by the ALCAT test and this work is continuing in several centres, already having been confirmed by Dr. Cabo-Soler in Spain.

During the past ten years we have continued to use the ALCAT test and presented a number of papers on various medical topics besides using the test on well over two thousand patients.

But my major interest during the last few years has been directed towards the mechanism of action that is demonstrated by the test, as I believe we are not witnessing the results of immune mechanisms but are seeing the result of pharmacological or toxic phenomenon. The white blood cells are capable of a number of actions when in contact with non- nutrients- xenobiotics and there is a wide and varied support for this hypothesis.

Cells may react in a number of says when bought into contact with xenobiotics, if soluble they may be engulfed and vacuolated and thus increase in size. The cells may degranulate and release substances that act on blood vessels and thus diminish in size or be exposed to such an extreme reaction that the cells disintegrate and the cell count falls. It can be demonstrated that certain cells will commence proliferation and an increase in DNA may be demonstrated, at this point the cells swell then divide and produce 2 small cells. The lining of the gut is loaded with cells capable of this series of reactions but if overwhelmed then peripheral cells become involved and it is almost certainly this phenomenon that the ALCAT test is detecting. Many of these reactions are directly chemical as can be demonstrated by subjects who are sensitive to such chemicals as Benzoic acid. Increasing challenges to the skin will produce increasing urticarial reactions until cells are depleted and high doses then fail to produce a reaction. These are not histamine mediated as the process cannot be blocked by anti-histamines.

Four patients were selected who had positive IgE negative ALCAT to foods, a second group were the reverse, ALCAT positive IgE negative and a control group who were negative to both. The patients produced a resting sample of urine, were then challenged with an individual food, and urine collected hourly over 12 hours. The results were analysed looking at the first 6 hours versus 6–12 hours. The IgE positive group were noted to have an increase in metabolite immediately falling off by hour 6, whereas the ALCAT positive group produced metabolites later, their peak being between 6 and 12 hours. The control group produced no histamine metabolites.

The last series of experiments were designed to show again the predictability of the ALCAT test but this time with substances known to be pharmacologically active in the body, and, as many of these have been incriminated in migraine we chose to look at healthy volunteers and patients suffering from migraine. The substances we tested were: gluten, tryptamine, octopamine, dopamine, lectin and chloragenic acid (naturally occurring substances), all produced a significantly positive result in migraine sufferers versus healthy volunteers, whereas histamine and tyramine produce similar results in healthy volunteers.

These series of experiment encouraged us that as important as food sensitivity may be, it is likely that both natural and man made chemical xenobiotics may be equally if not more important in some syndromes. Therefore, we now adapt the ALCAT test to embrace this possibility.

There are often associated with the food problems, other aspects which need attention; there may be disruption of the gut flora – the bacteria in the gut, essential for providing 25% of our energy needs and tests are necessary to determine what is the problem and how it should be treated. Some individuals are allergic to certain foods and this requires quite different tests to determine if allergic antibodies are being produced and this would lead to quite different treatment. Nutritional advice, sometimes psychological support, general medical examinations and investigations may be essential, so it is important that if illness is being caused by food then it should be managed by professionals who are knowledgeable about these matters and not simply dismissed. "I am afraid you will just have to learn to live with it" is of no use to the patient and reflects badly on the person giving this advice as there are now plenty of opportunities available for these individuals to improve, they should be investigated.


1. Peter J Fell M.D., Sally Soulsby S.R.N., et al Cellular Responses to Food in Irritable Bowel Syndrome, an Investigation of the ALCAT test. Journal of Nutritional Medicine 2: 143–149. 1991.
2. Lene Hoj M.D. Diagnostic Value of the ALCAT Test in Intolerance to Food Additives Compared with Double-Blind Placebo-Controlled Oral Challenges. Journal of Allergy, Asthma and Immunology 97 (1) Part 3. January 1996.
3. Lene Hoj M.D. Food Intolerance in Patients with Angioedema and Chronic Urticaria: An Investigation by RAST and ALCAT Test. European Journal Allergy & Clinical Immunology 50: 375. 1995.
4. Gilbert Kaats, Dennis Pullin and Larry Parker The Short Term Efficacy of the ALCAT Test of Food Sensitivity to Facilitate Changes in Body Composition and Self-reported Disease Symptoms: A Randomised Controlled Study. The Bariatrician. Spring: 18–23. 1996.


  1. No Article Comments available

Post Your Comments:

About Dr PJ Fell Lond.

Dr P J Fell is a Director of the Oxford Allergy Centre. He can be contacted on 01869 337323.

  • Water for Health

    Specialist online health store focused on hydration, body pH balance and quality nutrition.

  • nutrition and cancer

    by Sandra Goodman PhD The latest scientific research regarding Nutrition and Cancer. Full details at

  • mycology research MRL

    MRL markets mushroom products food grade US & Netherlands GMP standards. Health Professional Videos

  • June Sayer Homeopathy

    Training Academy Homeopathy Nutrition Reiki, Distant Learning. Diet, Health Screening, Detox, Stress

  • Liposomal Nutrients

    Optimum system for nutrient delivery to cells - fully bioavailable vitamins absorbed and metabolised

  • Seaweed as Superfood

    Comprehensive nutrient balance found in no other natural food but seaweed: colon health, weight loss

  • College of Ayurveda UK

    Diploma in Āyurvedic Medicine, 4-year self-paced distant learning program in Āyurvedic medicine.

top of the page