Commercial tests for food allergy exploit the fears of vulnerable individuals.  None of them has diagnostic value and what’s more, restricting the diet according to the results of the tests may lead to serious health problems.  Those were the damning conclusions from ‘Which’, the consumer organization, in a report released today.     

 

‘Which’ carried out its own research.  Four researchers, one with a serious peanut allergy, another with lactose intolerance and two more who had no symptoms of food intolerance assessed 4 different tests.  None of them was experiencing any symptoms of food intolerance at the time of testing.  

 

The tests used widely differing techniques.  They included analysis of hair samples for vibrational energy (Bionetics) or hair root DNA (Integral Health),  assessment the measurement of changes in muscle resistance caused the proximity of vials containing certain food extracts (kinaesthesiology),  measurement assessment of changes in body conductance when essences of foods are placed in the circuit (Vega),  and analysis of blood samples for circulating antibodies (IgG) to a range of different foods.  They are not cheap.  The cost varies between £45 for the cheapest session of kinaesthesiology to £275 for a full IgG food scan of 113 different substances.      

 

Each test was evaluated by two researchers, who compared results from two different laboratories or practitioners and in some cases sent duplicate samples under an assumed name.  The results were alarming.  Not only were the tests not replicated by the two different laboratories or practitioners, but analysis of duplicate hair and blood failed to achieve agreement.  None of the tests detected the researcher who had peanut allergy and only one detected the person who was intolerant to milk.  The tests did, however, pick up a whole range of other intolerances.  Kinaesthesiology even claimed evidence for a severe peanut allergy in one of the researchers who ate peanuts with impunity.  The diets recommended by the blood tests excluded up to 39 foods, creating the risk of nutritional deficiency.

 

The results for hair analysis, kinaesthesiology and body conductance are hardly surprising.  These are exercises in pseudo-science, they have no evidence base and their exponents deserve to be exposed as confidence tricksters, extorting money from vulnerable people under false pretences.  

 

The data  from the Yorktest and Cambridge Nutritional Services are, however, more worrying.  They measure circulating antibodies to a variety of food substances, their metholodology (ELISA) is scientifically valid, the technicians are trained and, as far is the Yorktest is concerned,  qualified nutritionists are available to offer advice on dietary modification.  The rationale and methods look good, but if they are that good, why is IgG testing not available on the NHS? 

 

 

Antibodies did not evolve to protect us against food – they are essential components in our cell wars system against invasion by microorganisms.  Food intolerance is like injury by ‘friendly fire’.    

 

Antibodies come in various classes.  IgA is secreted into the gut and acts like a fire blanket to immobilize and destroy bacteria before they have a chance to invade.  They are not directly implicated in allergies. 

 

IgG antibodies circulate in the blood stream.  They recognize and combine with the foreign organism,  tagging it, immobilizing it and rendering it  vulnerable to destruction by the body’s white cells.  They work quietly away all the time, ridding our body of invaders that could take over and damage it.  They, too, for the most part are not implicated in allergies.

 

IgE exists in the gut wall and attaches itself to highly reactive white cells called mast cells.  Mast cells function like grenades.  The combination of the IgE with a foreign organism pulls the pin on the grenade and the mast cell explodes releasing a cocktail of powerful chemicals, which causes spasms, secretion, inflammation, diarrhea and vomiting – an immediate reaction, which can make the subject feel very ill.  The battle itself is highly destructive, rather like the destruction of Gori in the recent  conflict in the Caucasus.  It is this damaging reaction – the immediate hypersensitivity – that can cause severe allergies.  NHS allergy clinics and immunological laboratories test for immediate hypersensitivity either by injecting small amounts of the food protein under the skin, where, if positive, it causes a wheal and flare or by examining the blood for specific IgE antibodies. 

 

IgE reactions are highly dangerous and are not deployed often.  Over a lifetime, the body develops a tolerance to most of the foreign substances that it encounters and can deal with these using a quiet combination of IgA and IgG.   The more extreme IgE response is only deployed when the body encounters some rare organism (or protein), that has caused damage before and it has not become tolerant to – like meeting somebody who has previously abused you.  IgE  elicits a rapid protective response that evicts the invader forthwith.  But the body, like a nation state with experience of dealing with other potentially threatening states, usually tends to quieter and more diplomatic means of dealing with the problem. 

 

Allergies might therefore be regarded as failure of tolerance – the persistent activation of an attack response (in immunological terms a Th2 response), even to food proteins that carry no threat to the body.  Allergy is like an extreme or dysfunctional attitude.  The hygiene hypothesis suggests allergies may be becoming more common because in our sanitized environment, we are less likely to encounter and develop tolerance to the whole range of parasites, bacteria and viruses early in life.  In other words we lack experience, see everything as a threat and over-react – even to the food we eat.   Recent research has shown that worms and helminthes turn the IgE system off.  This allows them to exist in symbiosis with us in our guts, but at the same time, they protect us against allergy.  This has led some to advocate administering worms as a treatment for food allergies.     

 

But hospital testing reveals that less than 2% of people with symptoms of food intolerance,  have evidence of immunological hypersensitivity – IgE activation.  So there must be something else going on.  So the focus has again swung to IgG. 

 

The rationale for IgG testing is as follows.  If, for any reason, in a normally tolerant person,  too many proteins get into the body, because – say – the gut has become inflamed and too permeable or the IgA system is defective,  then a  massive IgG response may join with the proteins to produce large clumps which may lodge in the tissues of the joints, the guts, the lungs or the skin causing local inflammation.  An elevation of IgG antibodies to specific foods, therefore, might indicate that enough food proteins are getting across to elicit this type of allergic response.

 

For the most part, however, raised IgG levels probably indicate quite the reverse – that the body is dealing with the invading protein with normal ‘tolerance’.  This would explain why the York and Cambridge tests detect so many ‘intolerances’ to foods that their subjects can eat without any risk at all.  It would also explain why the most common intolerances are to foods that are most commonly eaten  – there’s just more of them about – and why the results vary according to how much has been consumed.  Finally it would explain why subjects with no symptoms of food intolerance have elevated IgG.           

 

Several recent studies have shown that raised IgG levels are associated with the development of tolerance to flour in Baker’s asthma,  eggs in egg allergy and foods reintroduced after an exclusion diet. 

 

The dreadful paradox of all this is that Yorktest and Cambridge Nutritional Services may actually have a test for food tolerance rather than food intolerance.  If that is the case then dietary restriction based on the advice of this test would not only deprive people of what they like to eat but also may risk nutritional deficiency.

Read tomorrow’s blog for a discussion of what food allergies mean.

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