I shall preface this by saying that if you want to read a sensible guide to food allergies, intolerances and sensitivities then you would be well advised to read Dr. Adrian Morris’ site. Dr. Morris distinguishes these conditions and gives a good overview of their mechanism of action, where known, such as IgE mediation in allergy. He also presents a helpful overview of supervised elimination diets for children to assess whether foods are linked to a reaction.
If, however, you have no interest in learning the crucial differences between allergies, intolerances and sensitivities, and the implications for your child and family life, then read the Food for the Brain Guide to Understanding Food Allergies. As a pre-emptive strike against the need for consistency (as Emerson remarked, the hobgoblin of little minds), we learn:
The classic definition of an allergy is ‘any idiosyncratic reaction where the immune system is clearly involved’.
However, we are not really that interested in vague definitions that have no clinical meaning and would make it impossible to diagnose a condition and implement some form of treatment. Helpfully, the Food for the Brain Guide guide explains IgE mediated food allergies and then goes on to tell us about IgG food allergies, ignoring the convention that the latter is more usually referred to as food intolerance, rather than food allergy.
All of these ‘IgE-mediated’ reactions are immediate and severe and may be life-threatening. If your child has this type of allergy, you probably already know about it and are strictly keeping your child away from the offending food.
The most common type of food allergy involves a different marker called IgG. The difference here is that IgG reactions may take anywhere from an hour to three days to show themselves, are often less immediately dramatic in nature and are therefore much harder to detect. [Emphasis added.]
So, according to this, the commonest type of food allergy involves the IgG immunological mechanism. What about food intolerances and sensitivities?
Food intolerances and sensitivities are reactions to food where there is no measurable antibody response. Examples of these include lactose intolerance, where a child lacks the enzyme to digest lactose (milk sugar), usually resulting in digestive symptoms such as diarrhoea and abdominal discomfort or intolerance to the flavour enhancer MSG, which makes some kids hyperactive. [Emphasis added.]
So, allergies produce immunological markers but intolerances and sensitivities don’t produce a measurable antibody response. You will be relieved to learn that there are blood tests available that can take all the hard work out of having to run an elimination diet protocol to discover which foodstuffs your child is allergic to.
If your child has a history of infantile colic, eczema, asthma, ear infections, hayfever, seasonal allergies, digestive problems (including bloating, constipation and diarrhoea), frequent colds and any behavioural or learning problems, then you should suspect a delayed food allergy. In which case, you should have him or her tested to identify which foods are the culprit. The best test is called IgG ELISA and uses a finger-prick blood sample and a home test available from Yorktest. [Emphasis added.]
But, if you look at Patrick Holford’s own site and his associated ones that are trying to convince you of the benefits of the IgG ELISA YorkTest, and want you to buy one, it seems that the YorkTest IgG is a food intolerance test rather than a food allergy test. IgG tests don’t measure IgE; you typically measure IgE if you are performing a blood panel for allergy testing. If you wanted to run a blood panel for food allergy, then you would need to purchase an IgE test panel.
Yet, Food for the Brain told us that food intolerances don’t produce a “measurable antibody response”: if that is true, then why is Holford also recommending a test whose purported diagnostic rationale lies in the measurement of an antibody response? E.g., the YorkTest IgG test for food intolerance is measuring IgG antibody levels to identified foodstuffs.
I don’t know who wrote the Food for the Brain Guide to Understanding Food Allergies: despite the impressive number of professors on the Scientific Advisory Board (although, this does seem much reduced from earlier lists), nobody seems to have proofed this guide for legibility or commonsense before publication. It is confusing, misleading and potentially dangerous if this guide were to lead a parent to believe that they could confirm/disprove a food allergy by running an IgG test. It may be boring to state your definitions upfront in a piece, but this guide needed a much clearer definition of allergy, intolerance and sensitivity that would also make sense if parents followed-up on any of the advice such as reading about IgG food allergy tests that suddenly become food intolerance tests.
Ironically, there is an excellent test for lactose intolerance that is not mentioned in this Food for the Brain Guide guide. It is not a blood test, it is not something that you can purchase from one of Patrick Holford’s sites but it is a good diagnostic test that you can talk to your GP about if you suspect that your child has lactose intolerance: it is the hydrogen breath test.
If you suspect that your child has food allergies then you should talk to your GP about a referral to a clinical allergist. A clinical allergist will take a thorough medical history, order appropriate tests, and use both of these to arrive at a diagnosis: by themselves, direct-to-consumer tests, such as the ones recommended by Food for the Brain and Holford, may be a source of misdiagnosis and inappropriate allergen avoidance. It is entirely possible to have a positive result in a test but no clinical history of any reaction: if you were to act on the basis of the test result, it might result in needless allergen avoidance, considerable inconvenience, social difficulties and expense.
Some time ago, Sandy wrote: Fear of foods, contaminants and modern life. She quotes some disturbing findings:
Rona and Chinn found that around one half of parents who thought that their child was food allergic or intolerant altered their child’s diet, but only one third sought medical advice, and that some children were 4 cm shorter than controls. Unnecessary environmental and chemical avoidance, creating a perception of organic illness where none exists, or advising physical interventions when psychosocial factors are the source of symptoms, can impact on employment and social functioning. [Emphasis added.]
The parents highlighted in the Rona and Chinn took their power into their own hands because they couldn’t obtain formal help for their children’s perceived food intolerances; as a consequence, those primary school children are shorter than their non-food-intolerant peers by an average 1.5 cm.
If you suspect that your child has food intolerances or sensitivities, then you should talk to your GP and request a referral to an NHS dietitian. An appropriately qualified dietitian can take a medical history and give guidance on how to implement an elimination diet and monitor a child for symptoms. The dietitian will make sure that you know how to make up any missing nutrients from a child’s diet while, say, dairy is eliminated. If you can’t obtain a timely referral, then rather than pay for dubious tests or supplements, consider the following:
- if a GP is unable/unwilling to make a referral to an NHS Allergy Clinic, then ask for a private referral to a Clinical Allergy specialist. Even in London, for the cost of a YorkTest 113 foodSCAN test for intolerances, it is possible to purchase:
- a consultation and tests at a well-regarded allergy clinic
- a consultation with a leading consultant and researcher plus several tests
- a consultation with a leading consultant and researcher, but tests would be an additional cost
- outside London, I would expect people might be able to have a consultation with an expert and comprehensive and relevant testing
- several consultations with a dietitian (NB, appropriately qualified dietitian, not a nutritionist) who can guide and support the enquirer through an elimination diet.
If a parent suspects that a child might have a mix of allergies and intolerances and requires both (say) the YorkTest Allergy UK MAST (multi allergy screening test) and the 113 foodSCAN test, then the price comparison with the cost of seeing a relevantly qualified and experienced Clinical Allergy Consultant is even more favourable. Any of these suggestions are more likely to result in a more relevant outcome for the parent and child than an IgG test or following the advice in the Food for the Brain guide.
It can be psychologically gruelling, physically tiring and very expensive for families to have a child with a restricted diet: don’t implement one unless it is clinically necessary and you have been well-advised by appropriately qualified clinicians.
Edited: May 9, 14:00
Claire has usefully commented that it can be unwise/dangerous for parents to pursue elimination diets for children and then re-introduce the foodstuff: this is a particularly risky undertaking when the child has a history of asthma or eczema. It would be inappropriate to name them but there have been tragic instances where children have developed an anaphylactic reaction when their parents performed an at-home food challenge, following an elimination diet. It seems as if there are occasions when elimination of an allergen, followed by its re-introduction, produces an overwhelming allergic reaction in the form of anaphylaxis.
The Allergy Working Group has a number of recommendations for the provision of appropriate allergy services on the NHS (scroll down for pdf download). The following are quoted from their recommendations:
The following conditions should only be seen or procedures performed in Specialist Allergy Centres:
- Anaphylaxis, general anaesthetic allergy, local anaesthetic allergy, severe or multiple drug allergy, aspirin/NSAID intolerance, opioid intolerance, multiple food allergy, bee and wasp allergy, hereditary angioedema, occupational allergy, severe latex allergy
- Excluding allergy as a cause of disease (this is required by commissioners as funding is often sought for treatment in alternative allergy centres)
- Patients who require allergen immunotherapy (desensitisation): initiation, until maintenance therapy then supervision
- Any type of challenge testing
- When the diagnosis of allergy is in doubt, for example discordance between the history and objective skin/RAST tests
Multiple food allergy and intolerance in infancy and early life should be referred to a specialist paediatric allergist. [Emphasis added.]
