chapter 21 Allergies
INTRODUCTION AND OVERVIEW
One problem that has so far limited our ability to successfully treat allergy is what Dr Merv Garrett of the Australasian College of Nutritional and Environmental Medicine refers to as ‘labelling disease’.1 Allergy is a multifactorial problem, attributable to so many causal factors and appearing in so many different ways that labelling all its manifestations as allergy can mislead the practitioner into a narrow pattern of diagnosis and treatment. Any diagnosis of allergy should include a thorough investigation of the influences on that particular case, and investigation into the likely effectiveness and appropriateness of different possible treatments.
DEFINITION OF TERMS
Some people, however, may have many of the symptoms of classical allergy, but reactions, which may occur hours or days after the exposure, involving little or no IgE. While these people may experience delayed skin reactions, their immediate skin reactions and blood tests for allergens may be negative or weak. More than a decade later, there is much wider recognition of the diversity of allergic responses, and of the fact that IgE-mediated responses do not account for all allergies, especially food allergies.2–4
BACKGROUND AND PREVALENCE
It is difficult to obtain solid, consistent, up-to-date statistics on allergy, but throughout the Western world, a significant rise in the incidence of allergy has been reported since the 1950s. A report released by the House of Lords Select Committee on Science and Technology in July 2007 stated that, ‘Allergy in the United Kingdom has now reached epidemic proportions, with new, more complex and potentially life threatening allergies’.5 Allergies are also on the rise in Australia, which has one of the highest rates in the world.
A study by the Australian Centre for Asthma Monitoring revealed that, ‘the number of Australians hospitalised for severe life-threatening allergic reactions has more than doubled in the past 15 years’, particularly among young children.6 In a lecture at the Onassis Foundation in Greece, Dr Daphne Tsitoura said that if something is not done to stem this growth, one in two Europeans will have allergies or allergy-related conditions by 2015.7
Food allergies, many of which do not fit the IgE-mediated reaction pattern, are on the rise globally. In 2001, the US Food and Drug Administration reported that ‘Only about 1.5 percent of adults and up to 6 percent of children younger than 3 years in the United States—about 4 million people—have a true food allergy, according to researchers who have examined the prevalence of food allergies’, but those statistics only included ‘classic’ allergies involving IgE. After surveying 14,948 people about seafood allergies, Sicherer and colleagues concluded that 2.3% of the general population had credible seafood allergy, suggesting that food allergies are much more prevalent than generally allowed for in US government statistics.8
The House of Lords report on allergy noted the adverse effects of allergy on quality of life, especially for children, and on school and workplace performance.5 In addition to this, allergy places an enormous economic burden on society. For these reasons alone, it is not to be taken lightly, even when the allergies are mild. Even more insidious are the less obvious and ‘hidden’ health effects of allergy. It makes life miserable for many sufferers, and has been implicated in a large number of diseases and disorders, including degenerative disease.
AETIOLOGY
OTHER PARENTAL INFLUENCES ON INFANT ALLERGY
ENVIRONMENTAL AND LIFESTYLE FACTORS
External factors can cause allergy in children and adults. In 1998, Dr Stephen Holgate wrote, in the Quarterly Journal of Medicine, ‘While ∼40% of the clinical expression of an allergic disorder can be accounted for by genetic factors, for these to be manifest there is an absolute requirement for interactions with environmental factors’.12 The World Health Organization reported that, ‘convincing evidence demonstrates that a number of environmental factors—environmental tobacco smoke, poor indoor/outdoor climate and some allergens—contribute to the onset of allergic disease. Once the disease is established, these factors may also trigger symptoms’.13
Additional factors linked to the development of allergies include:
In an article on preventing allergies, AB Becker of the University of Manitoba, Canada, wrote: ‘It is increasingly clear that gene-directed environmental manipulation of allergy in a multifaceted manner during a “window of opportunity” is critical in the primary prevention of allergy and allergic diseases like asthma’.14 The ‘window of opportunity’ for most people is in the first year of life, when a multifaceted preventive strategy can help develop the child’s resistance to allergies. Research suggests that in the first year of life, allergies may be prevented by:
THE TWO PATHWAYS TO ALLERGY
Failure of the mucous membranes
One very important example of this is ‘leaky gut syndrome’, which researchers have shown to contribute to the development of allergies.15–18 The mucous membrane lining of the gut wall can be compromised by:
DIAGNOSIS
The practitioner taking an integrative approach to allergies must be willing to look beyond the expected parameters of diagnosis, as allergies have a varied and complex pathology due to the interactions of so many different elements: physiology, psychology, genetic make-up, situation, family and environment. Not only do different people manifest the same kinds of allergies in different ways, and not only are they multifactorial in cause, but one must consider the possibility of cross-reactions, where sensitivity to one substance causes a person to be sensitive to ingredients in several other substances. For example, a person with an allergy to melons may also be allergic to other fruits or even to pollen because of certain similar ingredients. Assessment of cross-reactive food allergens requires careful history, testing and perhaps oral food challenges.19
HISTORY
Through an examination of an infant’s dietary history, for instance, it is easy to establish a relationship between severe colic and cow’s milk, from which the practitioner can surmise that the colic is associated with cow’s milk intolerance (as reported by Iacono and colleagues20 and Hill & Hosking21) without resorting to distressing skin tests, and recommend dietary treatment.
History and other investigations are critical, even when the symptoms seem to indicate one kind of allergy. Food allergies or sensitivities, for instance, can lead to lung disease, asthma, eczema, and rhinitis, wheezing and other respiratory symptoms. Asthma can show up as food allergies and gastrointestinal symptoms. Food allergy or sensitivity is, in fact, often overlooked as a cause of asthma, especially because food allergies do not always show up in standard skin tests. Multiple chemical sensitivity with its complex combination of factors can also be missed by standard tests, and is usually diagnosed by history.22
Dietary and environmental history
Exposure to toxins
Clues to environmental factors are also to be found in the patterns of presentation of symptoms, and also in chemical testing, such as hair or urinary testing to identify environmental pollutants such as arsenic or mercury.22 Because a person can be allergic to just about anything, everything with which the person comes into contact should be considered, including common household chemicals such as:
SIGNS AND SYMPTOMS
INVESTIGATIONS
Most information will come from the history, and tests may also be administered, to identify or confirm major allergies and allow strategies to be precisely targeted. Various diagnostic procedures are available to test allergies and IgE-mediated allergies. Allopathic medicine uses various testing modalities to identify allergens and allergic reactions in sensitive individuals. Other diagnostic approaches include allergy symptom-rating questionnaire, food avoidance test, food challenge test, scratch test, elimination and challenge diet, rotation diet,23 pulse difference test,24,25 patch test, skin prick test (SPT), radioallergosorbent test (RAST), provocative neutralisation testing, immunoglobulin studies (IgE, IgA, IgM, IgG) and IgE-specific antigen studies.
Scratch or prick test
A drop of concentrated antigen is placed on the skin, usually on the inner forearm, which is then pricked or scratched so that a minute amount of antigen is absorbed. The size of a wheal surrounded by erythema compared with the control indicates a response to a problem substance. Generally, a wheal diameter of 3 mm × 3 mm is considered positive. However, there are several complexities and pitfalls in interpreting SPTs. If a sensitive person has high IgE levels, the scratch or prick test can accurately determine allergy to pollens, moulds, dust, dust mite and animal dander. However, if IgE levels are low, a wheal may not develop even if the person tested is sensitive to these inhalants. There is no standard battery of allergens tested—the history guides which allergen extracts are used.
Blood tests
Several allergy testing methods use the person’s blood. The radioallergosorbent test (RAST) is a blood test in which IgE and IgG antibodies are labelled with a radioactive substance. The amount of antibody found in the blood in response to a given food, pollen, mould, dust and so on can be measured with a Geiger-counter type of instrument. RASTs are useful when SPTs cannot be performed. The RAST can test for sensitivities to a large number of substances in a short period of time. It works only with immunological antibodies; it cannot identify problem substances for which there is no antigen–antibody response, but it does have the advantage of measuring IgG antibodies, confirming an IgG-mediated immune response to milk in milk-intolerant individuals.26
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