Soy Allergy

Food Allergies

Food Allergies

Peanuts can leave you breathless. Cat dander can lead to itchy eyes, a stuffy nose, coughing and sneezing. And most of us have suffered through those seasonal allergies with horrible pollen counts. Learn more...

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The Dutch Food Intolerance Databank ALBA

ALBA is perhaps the most influential of the food intolerance databanks worldwide. It was established in 1982 by the Agricultural University of Wageningen and became operational in 1984. Since 1988, the databank has been hosted by a division of the government research organisation Netherlands Organisation for Applied Scientific Research (TNO), located in Zeist. ALBA currently holds data on around 500 brands and 11 000 products from 150 manufacturers and retail organisations, representing approximately 25-40 of the total Dutch manufactured food market. The 'free-from' booklets represent just one of the services offered by LIVO - the National Information Centre for Food Hypersensitivity, based in The Hague. As well as distributing over 12 000 'free-from' lists to consumers every year, LIVO provides a telephone enquiry service and produces general consumer information on food allergy and intolerance. ALBA distributes a further 2000-3000 special combination 'free-from' lists to consumers...

False food allergy or pseudoallergy

These types of reaction outnumber the true immunologically mediated ones. Various clinical syndromes are also known to be induced by such reactions, for example chronic urticaria, anaphylactic shock, intermittent diarrhea and irritable bowel syndrome, migraines, rhinitis and asthma. Table 3 lists some of the substances and mechanisms implicated in false food reactions. Table 2 Investigations for the diagnosis of food allergy Table 3 Biologically active substances and mechanisms playing a role in false food reactions Table 3 Biologically active substances and mechanisms playing a role in false food reactions

Principal Mechanisms and Pathophysiology of Food Intolerance

The principal mechanisms resulting in food intolerance and the pathophysiology (where this is understood) are discussed below. Food Allergy Lactase deficiency An example of an enzyme defect causing food intolerance is lactase deficiency. In this condition, which is primarily a disorder that affects infants and young children, there is a reduced or absent concentration of the enzyme lactase in the small intestinal mucosa. Affected individuals are unable to break down ingested lactose, the main sugar found in milk, and which if unabsorbed passes into the large intestine, where there are two consequences. One is an osmotic diarrhea. The other is that some of the unabsorbed lactose is broken down by intestinal bacteria, accompanied by the production of gas (hydrogen) leading to abdominal distension and flatus and the production of organic acids that cause perianal soreness or excoriation. The production of hydrogen, its absorption into the bloodstream, and its excretion in the breath lead...

Nontoxic food reactions

These reactions are either immune-mediated or non-immune-mediated. When the reaction is immune-mediated the term 'food allergy' is applied, and when non-immune-mediated the term 'food intolerance' is recommended. Both types of reactions are reproducible and depend on an individual's susceptibility. Food allergy Food allergy itself can be subdivided into two categories, IgE-mediated food allergy and non-IgE-mediated food allergy (Fig. 1.1). Immunoglobulin (Ig) E, or IgE, is the main antibody involved in induction of immediate allergic reactions. Most of the research evidence available on food allergy has been focused on IgE-mediated food allergy. Indeed, most common food allergies are mediated by IgE antibodies. The mechanism underlying IgE-mediated food allergy is fairly well established. Symptoms of this form of food allergy appear rapidly, are varied and range from anaphylaxis to skin reactions.2 Non-IgE-mediated food allergy is less well understood. Such allergies include reactions...

Food Intolerance and Allergy

According to some surveys, 20 to 25 of people in the U.S. are allergic to certain foods. Self-reported information based on changes in dietary habits to accommodate a food problem is likely to be mostly erroneous. Often, patients who say they have a food allergy avoid a food and never seek medical advice. Diagnosis of food allergies is overworked, poorly defined, and misused. There are many misconceptions about food allergies, such as understanding of the causes of food allergies and their symptoms. A minority of practitioners who have overemphasized the magnitude of the role of food allergies in human illness have greatly contributed to this misconception. The American Academy of Allergy and Immunology has sharply criticized their concepts and questioned their practices. Double-blind placebo-controlled studies indicate that food allergies occur in 2 to 2.5 of the population. It has been estimated that 1 to 3 of children under the age of 6 years have allergies to foods. The frequency...

Novel and uncommon food allergies

There are a number of foods that are eaten in geographically or culturally quite specific populations and adverse food reactions are limited to these groups. However, with diversification of cultures and diets across the globe, particularly in developed countries, adverse reactions to these foods may be seen in many other countries. A good example is sesame seed, to which allergy in Western countries was rarely reported (Rance et al. 1999). However, there are reports of an increasing number of cases of sesame seed allergy in France coincident with the increase in Middle Eastern food and fast food bread (Kolopp-Sarda et al. 1997). Sesame seed often causes severe clinical allergy hence its importance. In France sesame seed was responsible for 0.6 of IgE-mediated food allergies seen in recent years in an allergy clinic population (Rance et al. 1999). Table 10.12 makes the point that uncommon food allergens are important causes of food allergy in specific countries. In an Israel allergy...

Characteristics of patients with food intolerance

Subjects reported reactions to the common allergenic foods - legumes, tree nuts, crustaceans and fish. Twenty-one out of the 22 subjects in this group had positive skin prick tests to the offending food. The second group reported reactions to food such as sugar, wheat, egg, cured meat and yeasts. Only four out of the 23 subjects in group 2 had a positive skin prick test in this group (evidence of IgE) that supported their reported reactions (chi-squared 24.68, p value 0.0001). The second group's symptoms started at an older age - 28.9 years versus 17.1 years (p 0.0015) - and were related to a much broader range of foods - 25.6 versus an average of 5.5 (p 0.0002).

Definition of Food Intolerance

Food intolerance can be defined as a reproducible adverse reaction to a specific food or food ingredient, and it is not psychologically based. Although this appears straightforward, there are a number of One problem with our definition of food intolerance is the lack of definition of what constitutes an adverse reaction. All eating causes reactions, which include satiety, feeling warm, the urge to defecate (due to the gastrocolic reflex), and weight gain. The definition above does not take into account dosage. Large quantities of certain foods may result in disease in certain individuals, although such disorders are not usually included in the category of food intolerance. Any food, however harmless, can be harmful if taken in excess. Notable examples of this are 3. In those who are genetically predisposed, ingestion of an excess of purine-rich foods contributes to hyperuricemia, leading to gout, a disorder which is not usually regarded as a form of food intolerance.

Mechanisms of food intolerance and food allergy

With regard to underlying mechanisms and trigger factors for food allergy and food intolerance, it is fair to say that our level of knowledge is very much in its infancy. We know, for example, that some individuals are more susceptible than others. Atopy (predisposition to allergic disease) is heritable, so could this What role do food allergens themselves play We know generally that the most common foods implicated in food allergy and food intolerance are egg, milk, peanuts, nuts, fish and soya.5-7 On average, an individual's gastrointestinal tract will process about 100 tonnes of food during a lifetime. Everything we eat is foreign to our body and potentially immunogenic. What is so special about some food allergens Why do only a proportion of people have the ability to sensitise and cause an allergic reaction What is the natural history of food allergy and food intolerance We do not know why with some foods, such as milk, sensitivity is lost with time, while with others, such as...

Background to the European Food Intolerance Databanks project EFID

The European Food Intolerance Databanks project developed as a result of the success of the food intolerance databanks in the Netherlands and the UK. In the early 1990s, the Leatherhead Food RA was aware that, despite the usefulness of food intolerance databanks in the management of food intolerance, the UK and Dutch databanks were the only ones in existence in Europe. After considerable consultation with experts, Leatherhead submitted a proposal to the Commission of the European Communities under the Agriculture and Agro-Industries Research programme for funding, to create a new network of food intolerance databanks across Europe. The project was accepted for funding.

Intervention strategies aimed at preventing adverse food reactions

Most of the work in this area has been directed at preventing allergic sensitisation (primary prevention), rather than the prevention or suppression of clinical disease once sensitisation has occurred (secondary and tertiary prevention respectively). Up to now, no therapy has been shown to be of value in secondary or tertiary prevention of adverse food reactions. Furthermore, whilst some studies show that pharmacological intervention may alter the incidence and natural history of asthma, there are no comparable data regarding adverse food reactions (Bustos et al. 1995, Warner 1997). This section therefore concentrates on the dietary intervention studies set up with the aim of preventing or reducing the occurrence of adverse food reactions. Some of the studies look at children with a high risk of atopy (usually defined as those children with at least one first-degree relative with documented atopic disease), others at unselected children from the general population. Most do not focus...

Commonly reported food allergies 1031 Cows milk

Cows' milk is an important weaning food in many countries. In recent years it has become practically ubiquitous, being found in an increasing range of commercially produced foods (Sampson 1998). There is extensive cross-reactivity between milks of different species (Businco et al. 1995, Carroccio et al. 1999). Cows' milk is one of the first foods to enter an infant's diet and therefore is often the first to cause problems. Adverse reactions to cows' milk can be divided into two main groups, immunological (IgE or non-IgE mediated) or non-immunolo-gical (Host et al. 1997, Host and Halken 1998). This latter group is mainly due to lactase deficiency and may be difficult to differentiate clinically from non-IgE mediated cows' milk allergy (Host et al. 1997, Bruinjzeel-Koomen et al. 1995). Cows' milk allergy gives rise to a spectrum of disease from immediate symptoms ranging from urticaria to anaphylaxis (Goldman et al. 1963, Sampson et al. 1992) and late symptoms which may not develop for...

Fish and Shellfish Allergies

Seafood is a common source of food allergies. About 250,000 Americans experience allergic reactions to fish and shellfish each year. If you suspect that you have any food allergies, see an allergist for a careful evaluation. This generally includes a medical history, physical examination, and skin or blood testing. If you are found to have a fish or shellfish allergy, the best advice is to avoid fish or shellfish altogether. That may be harder than it sounds. You may not be aware that seafood is an ingredient in a dish that you are eating. Be sure to check the labels of any product you buy. In addition, make sure that persons close to you are aware of the potential for this kind of allergic reaction. Many people with a food allergy wear medical alert bracelets. Another important safety note is that shellfish are a common trigger of allergic reactions in some people (see sidebar Fish and Shellfish Allergies, page 317).

Igemediated Food Allergies

In IgE-mediated food allergies, allergen-specific IgE antibodies are produced in the body in response to exposure to a food allergen, usually a protein. These IgE antibodies are highly specific and will recognize only a specific portion of the protein that they are directed against. Occasionally, IgE antibodies produced against one particular protein in a specific food will confer sensitivity to another food either because the food is closely related or because it shares a common segment with the allergenic protein. Some food proteins are more likely to elicit IgE antibody formation than others. Although exposure to the food is critical to the development of allergen-specific IgE, exposure will not invariably result in the development of IgE antibodies even among susceptible people. Many factors, including the susceptibility of the individual the immunogenic nature of the food and its constituent proteins the age of exposure and the dose, duration, and frequency of exposure, are...

Drug Treatment in the Management of Food Allergy

At present, drug treatment has little part to play in the management of food allergies. There are two exceptions. First, there are a very small number of cases in which the reaction to a food is exclusively gastrointestinal, and in whom the reaction can be blocked by taking the drug sodium cromoglycate by mouth 20min before the trigger food is swallowed. Second, there are a small number of individuals who develop the life-threatening reaction, of anaphylactic shock when exposed to a trigger food. There are three ways in which anaphylactic shock may prove fatal. First, rapid swelling of the soft tissues in the pharynx may completely obstruct the airway the treatment is to bypass the obstruction, either by passing an endotracheal tube, or by performing a tracheostomy. Another mechanism is severe shock, with a profound drop in blood pressure the life- A number of new approaches to the treatment of IgE-mediated food allergy are being examined. In a double-blind placebo-controlled study of...

Introduction the law and food intolerance

The results of a food intolerance condition can vary from mild discomfort through severe pain to tragedy. How can the law help to regulate this situation and protect the consumer whilst providing a framework in which business can operate How successful is it in achieving this objective Throughout history laws have existed to protect the consumer against the adulteration of food, whether deliberate or accidental. Watering down of milk and the contamination of food with heavy metals have long been the subject of investigation and prosecution. How does this translate into modern life and the problems of food intolerance The first point to be clear about is that with a few minor exceptions, the law does not specifically recognise or refer to the problem of food intolerance and allergic reactions. It is therefore necessary to examine the legal provisions that do exist in order to see where they can be of help to the sufferer and provide protection against inadvertent consumption of a food...

Interpreting data on the natural history of food allergy

Table 10.9 Epidemiology of adverse food reactions to food additives - key studies Table 10.9 Epidemiology of adverse food reactions to food additives - key studies (a) egg, milk or soy allergy (a) egg, milk or soy allergy Figure 10.2 Natural histories of different food allergies. Figure 10.2 Natural histories of different food allergies.

The need for hypoallergenic foods

Food proteins are essentially foreign proteins capable of eliciting immunological responses. Any food protein may be allergenic if it can be absorbed intact or as substantial fragments, through the gut mucosa, and then evoke an immune (allergic) response. Some foods, such as rice and vegetables, are less allergenic than others, such as milk, egg and nuts. The intrinsic properties of the protein, the overall composition of the food, and the processing (especially thermal processing) all have an effect on the allergic potential. In the management of food allergy it is possible to exclude the food responsible for symptoms and to replace it with less allergenic foods. In certain situations it is not possible simply to eliminate the food, e.g. milk during infancy. Up to 2.5 of infants are affected by cow's milk allergy (CMA) in the first two years of life, although most of these children will outgrow their reactivity within 2-3 years. However, during the interim period an alternative milk...

Food allergyintolerance

Food allergy in the cat may be associated with concurrent flea bite, inhalant or flea-collar hypersensitivity (White 8c Sequoia, 1989). Food allergy as a disease is a well-recognised cause of feline dermatological problems (Carlotti et al, 1990 Rosser, 1993), the prevalence of which varies from rare to common according to different authors. The pathophysiology of this syndrome is not completely understood. Adverse reactions to food may be either toxic or nontoxic if they are non-toxic they may be either due to intolerance or to immunological (allergic) reactions. Food allergy may be defined as an immunologically mediated excessive reaction to food substances, to be distinguished from food intolerance where enzyme deficiencies, pharmacological factors and toxic reactions, among others, may be implicated. The diagnosis of food allergy is achieved with a diet trial using a source of protein and carbohydrate to which the cat has had no or minimal exposure. This may be home cooked or, more...

Documenting Possible Food Allergies

The diagnosis of food allergy is made from the history, supported by investigations and by responses to avoidance of specific food triggers. Since the value of investigations is limited, it is especially important to obtain a clear history. There are a number of practical points to be made Failure to seek inconsistencies such as these is one factor that is responsible for the overdiagnosis of food allergy.

Cellmediated Food Allergies

Cell-mediated food allergies are sometimes called delayed hypersensitivity reactions, because the symptoms of these reactions typically appear 6 to 24 hours after consumption The T lymphocytes responsible for cell-mediated allergies abound in the gut-associated lymphoid tissue. Intestinal T lymphocytes are likely to be very critical in food-related, delayed hypersensitivity. However, the inaccessibility of these lymphocytes has hampered experimental studies of the role of cell-mediated reactions in food allergies. As a result, the prevalence and importance of cell-mediated food allergies remains unknown. Celiac disease is triggered by the ingestion of the protein fractions, specifically the gliadin proteins, of wheat and related grains. Other grains, such as corn and rice, do not contain similar gliadin proteins. As with IgE-mediated food allergies, most consumers do not react adversely to the ingestion of these particular grain proteins. In susceptible individuals, a particular...

Common food allergies

Table 10.10 compares clinical reactions to foods, and Table 10.11 compares skinprick specific IgE reactions to foods, between allergy clinic populations from different countries. As such they deal with a selected population and some studies involve small numbers. They show that cows' milk and egg are among the 2-3 commonest foods causing allergy in most countries. Peanut, fish, soy, wheat and shellfish are among the next most common groups of foods causing allergy, although significant variations occur between countries. Thus, for example, shellfish allergy appears to be more common in countries such as the Philippines, Thailand and Singapore where it is a part of the staple diet from early infancy, than in many other countries where it is consumed later and less commonly. In contrast, clinical peanut allergy which is a big problem in Western countries appears to be less common in most Asian countries, and also in Spain (Crespo et al. 1995). Thus in Japan it is very rare (Hill et al....

Unreliability of Self Reported Food Allergy

Reports of food allergy from individuals or parents of children are notoriously unreliable. Such reports have to be treated with scepticism. It is common for parents to believe that foods are responsible for a variety of childhood symptoms. Double-blind provocation tests in children with histories of reactions to food only confirm the story in one-third of all cases. In the case of purely behavioral symptoms, the proportion that could be reproduced under blind conditions was zero. The same is true of adults' beliefs about their own symptoms. If unnecessary dietary restrictions are to be avoided, one has to be sceptical, and it may be necessary in some cases to seek objective confirmation of food intolerance. The gross overreporting of food allergy has to be borne in mind when examining data on prevalence that are based on unconfirmed subjective reports.

Milk Intolerance Lactose Intolerance

The majority of children can tolerate lactose during a diarrheal episode. A small proportion of children with diarrhea may not be able to digest lactose and are therefore not tolerant of milk- and lactose-containing formulas. This is more likely to occur among young children who only receive animal milk or formula in their diet and who have persistent diarrhea, and it rarely occurs in children on a diet of breast milk. In a lactose-intolerant child, milk- and lactose-containing formulas result in a significant increase in stool output. Stool output reduces dramatically when the milk- or lactose-containing formula is stopped. The warning signs of lactose intolerance include deterioration of the child's clinical condition, signs of dehydration, and an increase in the stool volume when milk feedings are given. However, only when the child is not gaining weight, eating less, and not fully alert is this a real cause for concern. This condition can be managed by continuing breast feeding....

Food intolerance databanks

Many countries throughout Europe have food intolerance databanks managed by a central group, with information provided by companies. They collate information from various food manufacturers and produce comprehensive lists of products free from the key allergens. In many cases the booklets they produce (milk free, egg free, etc.) are available to health professionals, especially dietitians, who are then able to work with sufferers of food allergy to help them select suitable foods and also meet their nutrition requirements. The lists provide useful compilations of products suitable for particular diets, but are not without their pitfalls. Often they are updated only on an annual basis and risk becoming out of date even whilst they are still being issued. Additionally, they are not suitable for information on nuts and peanuts, as such information can quickly become outdated and is more dangerous than useful, for the reasons outlined above.

Diagnosing adverse food reactions

Different studies vary considerably in their working diagnostic criteria for food allergy. This has an important influence on the resultant measurement of prevalence and incidence in a population. In looking at IgE-mediated allergic problems, there are three levels of diagnostic criteria (1) questionnaire-based histories, (2) specific IgE and or skinprick testing and (3) food challenges (see Chapter 3). If, for example, we compare two population studies defining the prevalence of cows' milk allergy, one using skin testing and the other questionnaire-derived data, a higher prevalence will emerge in the latter study design. Double-blinded, placebo-controlled food challenges represent the gold standard but can not be practically used in large population-based studies where a combination of skinprick testing and questionnaire-based histories is more applicable.

Methodological issues 1021 Defining adverse food reactions

There are internationally agreed definitions for adverse food reactions, as have been discussed in Chapter 1. Unfortunately, terms such as 'food intolerance' are still used inconsistently. Thus the term 'intolerance' according to internationally agreed definitions is taken to mean physiological reactions to foods that do not have an immunological mechanism. However the term 'cows' milk protein intolerance' is often used to describe an immunological reaction to cows' milk that is non IgE-mediated (Host et al. 1997). It is not uncommon for authors to use several definitions of food allergy or food intolerance within a single publication. Any critical analysis of epidemiological studies must begin with a detailed understanding of the definitions used (for example, Table IV in Zeiger et al. 1999). This is of critical importance in comparative studies where like must be compared with like. The international definitions of adverse food reactions exclude food aversion. Such aversions have a...

Measuring the frequency of adverse food reactions and relating this to the natural history

There are a number of ways of measuring the degree to which a population is affected by a disease process such as food allergy. The best approach depends on the question being asked. Investigators usually measure either the incidence or the prevalence. The incidence is the number of new cases of adverse food reactions developing over a specified time. This is a useful measure when studying causality and possible preventative strategies but it gives little idea of the proportion of the population affected by the problem. The prevalence is the proportion of a specified population who suffer from adverse food reactions at a particular time. This figure is useful for gauging the health burden imposed by the problem in a population. Prevalence rates reflect two dynamic processes the acquisition of new cases of allergy in a population (incidence) and the simultaneous loss of allergy in that population (either due to death or clinical remission). Therefore a static prevalence between two...

Food Allergy

More recently, the discovery of IgE imrnuno globulins by Ishizaka has considerably increased our understanding of immediate type I hypersensitivity. Having a more accurate means of measuring IgF-mediated reactions, it soon became evident that only a modest part of all the intolerances due to food could be verified by these new in vivo and in vitro procedures. Consequently, the concept of false food allergy (pseudoallergy) gained in importance and now, besides IgE-mediated reactions, a large variety of mechanisms has been proposed and sometimes verified by appropriate techniques. 3. Food intolerance or pseudoallergy pharmacologic, enzymatic and undefined reactions.

Toxic food reactions

Classification Adverse Reactions

In principle, these are reactions which could occur in any individuals if the dose is high enough to trigger a reaction. They are usually caused by direct action of food components without involvement of immune mechanisms. Toxic compounds which trigger such reactions can occur naturally, such as from eating a puffer fish complete with its poison sac Or they can be contaminants of food. Although such reactions are fairly distinguishable from non-toxic food reactions in terms of mechanism, one has to be careful when diagnoses are made, since some of the symptoms may be similar.

Lactose Intolerance

As many as 50 million Americans are estimated to have lactose intolerance an inability to adequately digest ordinary amounts of dairy products such as milk and ice cream. As obvious as the symptoms of lactose intolerance may be, it is not easily diagnosed from the symptoms alone. Many other conditions, including stomach flu and irritable bowel syndrome, can cause similar symptoms. Persons with milk allergies should avoid milk, but those with lactose intolerance often do not need to follow a diet that is completely lactose-free. The following suggestions may help

Nonimmunological mechanisms

Enzymatic food intolerance is due to an enzyme defect which could result from an inborn error of metabolism or could be secondary to a number of disorders. The most common food intolerances in this category are disaccharide deficiencies, galactosemia and phenylketonuria. Amongst disaccharide deficiencies, lactose intolerance is the most common. Lactose deficiency can be congenital, persisting in the neonatal period, or can be acquired where it presents later.19 These deficiencies are genetically based and not due to an environmental factor. Secondary lactase deficiency often occurs following an episode of gastroenteritis. Many foods contain pharmacologically active components. A pharmacological food intolerance is usually evident soon after eating the food responsible. The amount of food ingested to elicit a reaction varies from person to person and may even vary in the same individual over time. The pharmacological components can either initiate a reaction directly themselves or...

Collaboration with governments

For many years, food allergy and intolerance had a poor public image. Despite the progress made in this field by a small number of dedicated scientists and physicians, allergy found itself on the fringes of medicine, dismissed altogether by some doctors, who regarded it as a convenient scapegoat for undiagnosed conditions that had other, unknown causes. People who claimed to suffer adverse reactions to food were accused of jumping on to an allergy bandwagon. Perhaps these accusations were justified in some cases, but many doctors threw out the baby with the bathwater. The cause was not helped by articles published by lightweight glossy magazines, which made extravagant claims about food allergy which plainly had little basis in science but were merely sensationalist. Soames was an honourable man who would be unlikely to have a hidden agenda and indeed this proved to be the case. He said he was 'staggered' by the scale of the problem of potentially fatal food allergy and announced that...

The Food and Chemical Allergy Association

The Food and Chemical Allergy Association, based at 27 Ferringham Lane, Ferring, West Sussex BN12 5NB, came into being as a result of a letter sent to a daily newspaper in 1976 by its founder, Ellen Rothera. She had been ill for eight years and came to believe that food allergies due to a malfunctioning immune system were the root cause. She managed to stabilise her condition and make a recovery. Ellen's letter to the Daily Express was not only published, but given a leading position. As a result she was inundated with letters and telephone calls from people desperately seeking answers to their own medical conditions. A small group gathered for a meeting and formed an association, which set out to find doctors with knowledge of allergy, learn from them and continue in a self-help role. A committee was formed and a secretary appointed to answer all enquirers. The FCAA continued in this manner for some years but eventually its role was changed to that of an advisory service. Today the...

Handling food allergens in retail and manufacturing

Food allergies can be uncomfortable, severe or potentially fatal to those who suffer them, depending on the nature of the reaction. The most common advice to sufferers is to avoid consumption of the trigger food in the diet. On the surface this seems a relatively simple and straightforward means of avoiding reactions. However, the fact that some individuals can react to minute amounts of the trigger food combined with the fact that the most common triggers of food allergies (milk, egg, wheat and nuts) can be widespread throughout a host of different foods means that avoiding allergens can be a time-consuming process. All food manufacturers have an overriding legal responsibility to ensure that their products are safe and fit for the purpose intended. They must also comply with the relevant labelling legislation. The first step is to identify the key allergens. These are the allergens that are the most common causes of food allergies. Following this, a comprehensive evaluation of...

The catering industry

Chartwell, the school catering company, has devised a code of practice for its catering managers entitled 'A positive approach to managing food allergies in educational establishments'. This eight-page document explains in depth what anaphylaxis is and what causes it. More importantly, it outlines a series of steps that managers are expected to take, including collecting information from students or parents, recording this information and reviewing it regularly, communicating thoroughly with all staff, and identifying and training key members who will be responsible for having a full knowledge of recipes and ingredient information.

Peanuts and tree nuts

Over the last few decades, peanuts have become a ubiquitous part of the Western diet as they are a versatile form of easily digested protein (Lucas 1979). In a study looking at the use of dietary manipulation to prevent the development of food allergy, all infants in the control group were exposed to whole peanuts by their second birthday (Zeiger et al. 1989) occult exposure probably occurs even earlier. Adverse reactions to peanuts and tree nuts are generally IgE mediated, occurring rapidly with subjects presenting with dermatological, respiratory and gastrointestinal manifestations (Hourihane et al. 1997). Peanuts and tree nuts are responsible for a third of all admissions with anaphylaxis (Bock 1992). Peanuts are part of the legume family, they are more closely related to peas, beans, soy and lentils than the tree nuts. It has been suggested that there is extensive cross-reactivity between peanut and tree nuts in terms of sensitisation but not clinical reactivity (Sampson and...

Collaboration with the food industry retail and manufacturing

Because public attention had been focused on peanuts and nuts - those foods most commonly implicated in severe reactions - there is a danger that food companies may overlook problems presented by other ingredients. Those occasionally implicated in the UK in serious incidents include milk, egg, sesame seeds and shellfish. The most frequent problems appear to be caused by minute amounts of milk products, quite legally undeclared under the 25 rule. A few examples are as follows. A 12-year-old boy with severe milk allergy suffered a moderately serious reaction when he ate an individual apple pie manufactured by a major UK company. Quite openly, the company said milk was present in a minute quantity - believed to be 0.006 of the finished product. The same boy suffered a reaction when he ate a cereal product made by a major manufacturer. Two other children reacted to small quantities of milk at around the same time -one to a sausage, the other to a crisp-type snack. In all these cases, the...

Avoidance therapy 521 General principles

The diagnosis of food-related symptoms should not be taken lightly, as food avoidance can be difficult, expensive, disruptive and even harmful to the health of the patient, especially in infants and young children1 (Table 5.1). The increasing complexity of our food intake and a higher proportion of packaged cooked foods in our diet make the avoidance of a particular food difficult (Table 5.2). The food industry has become increasingly important in the lives of patients with food allergy and intolerance.2 Those involved in the processing and packaging of foods should be aware of the basic principals of food intolerance and how changes in the food processing packaging might affect the lives of millions of people with food intolerance3 (Table 5.3). (Report of the FAO Technical Consultation on Food Allergies. Rome, Italy, 13-14 November 1995, Food and Agriculture Organisation of the United Nations, 1995.) All ingredients, particularly highly allergenic foods, should be clearly stated...

Occupation and smoking

These diseases are not all Type I, IgE-mediated reactions. Some cases of occupational asthma and some of contact dermatitis occur as a result of irritation.12 Hypersensitivity pneumonitis occurs as a result of a Type III or possibly a Type IV hypersensitivity reaction.13 As with non-industrial food allergy or intolerance, the pathophysiological mechanism affects the choice of diagnostic tests.

How common is anaphylaxis

A French study28 supports Bock's findings from Colorado. This multi-centre study investigated the presentation rate of food-induced anaphylactic shock to 46 emergency departments, 29 dermatology units and 19 internal medicine departments. In 794 reported cases of anaphylaxis, food was implicated in 81 cases (10 ). Unusually, only 19 patients (23.4 ) had known food allergy. The presence of the causative allergen in 'hidden form' contributed to 25 cases (31 ) of food-related anaphylaxis. An enhancing factor, such as alcohol consumption or exercise,29 was present in 221 cases (27.8 ).

The legal background labelling

The practical protection which individuals with food allergy and intolerance can expect from the law is information rather than elimination. To this end, comprehensive food labelling requirements have developed. Throughout the European Union these requirements are largely harmonised and stem from EC Directive 79 112 on the labelling and presentation of foodstuffs. The provisions are enacted within the UK as the 1996 Food Labelling Regulations. Although it originated two decades ago, the Directive and its enactments in EU Member States have been progressively updated over the years. The legislation requires that all foods are labelled with either a legally provided name or a customary name which is well understood by purchasers in the place of purchase, or a true name which accurately describes the food. A list of ingredients is required for most foods which details what they contain, including any additives. Notice the emphasis on the word 'most' as with many requirements, there are...

Sources of further information and advice

The Ministry of Agriculture, Fisheries and Food has produced information packs for the catering industries on how to anticipate the problems that might arise from allergic individuals in their restaurants. The Anaphylaxis Campaign, the British Allergy Foundation and their American counterpart, the Food Allergy Network, are excellent sources of rationally prepared and non-hysterical advice for individuals affected by food allergy and intolerance. The American Academy of Allergy, Asthma and Immunology has a website that has free patient information available, links to other sites and access to American physicians who may treat individuals. The Anaphylaxis Campaign has recently gone online. The British Allergy Foundation website is rather rudimentary at present.

Prevention of allergy

There is general consensus that the prevalence of asthma and other atopic diseases, including food allergies, is increasing. A history of allergic disease in the immediate family (atopic heredity) is the most important risk factor. Recent studies indicate that exposure to allergens in utero and in the first few months of life is critical in the development of allergic disease in children with an atopic heredity. In children at high risk, reduction in exposure to allergen should lead to a decline in disease prevalence. Food proteins are important allergens in early childhood. A hypoallergenic diet has therefore been suggested as a means of preventing the development of allergy. Experimental evidence indicates that the child can be sensitised in utero. It is sometimes advised that an atopic mother should avoid highly allergenic foods during pregnancy. However, there is concern that this might adversely affect the growth of the foetus. Avoidance of allergens during early infancy has been...

Other nonIgE antibodies

The body also is capable of producing other types of antibodies such as IgM, IgG and IgA against foods. Some studies have claimed a role for IgA-secreting cells, which have been shown to rise after ingestion of a particular foodstuff, or IgG4 that is said to correlate with clinical hypersensitivity. No studies have been able to demonstrate the role of these antibodies in the pathophysiology of food allergy. Food-specific non-IgE antibodies seem to be much more likely to reflect the particular diet of the individual, a normal phenomenon rather than diagnostic of disease.

Inappropriately applied laboratorybased tests

There are laboratory-based tests, some in common usage, which have not been shown to identify food allergies or intolerances with any accuracy. Lymphocyte subset counts and lymphocyte function assays are useful for diagnosing congenital or acquired lymphocyte cellular immunodeficiency states, but not allergic disease. Cytokines and their receptors are involved at many levels of the immune response. The correlation of assays with disease, and in particular their diagnostic value, is yet to be established.

The accuracy of diagnostic tests

Every disease has a rate of prevalence and incidence within both the general population and specific populations. The term 'prevalence' is a statistic based upon a particular point in time. It refers to the number of cases of a particular disease divided by the total number of people within the population and is usually represented as a percentage. 'Lifetime prevalence' is the number of people within a population who may have a particular disease at some time in their life, expressed as a percentage of the total population. The term 'incidence' refers to the number of new cases of a disease occurring over a specified period of time. The two terms are useful for different kinds of disease. The prevalence of a disease is often useful for more chronic diseases - those diseases which people rarely recover from, but also rarely cause death. A useful example is an estimate of the lifetime prevalence of peanut allergy within a given population. Diseases with high recovery rates or with high...

The diagnostic pathway

Diagnostic tests for food allergy, as with all medical tests, cannot be discussed in isolation. They are only one part of the whole diagnostic pathway. When an individual presents a particular problem to a health professional, a diagnostic pathway is embarked upon. This pathway starts with the professional taking the individual's medical history, the story of their particular problem. This is often complemented by an examination. The pathway may or may not conclude with particular tests. All diagnostic tests should be seen within the context of this pathway. Tests only serve to add further pieces of information to that already gleaned from the history and examination. They very rarely alone give a definitive answer. This chapter will start with an explanation of how to judge any test's 'worth'. It will then describe particular aspects of the history and examination relevant to the diagnosis of food allergies and intolerance. There will then follow an introduction to the wide range of...

Electrodermal testingelectroacupuncture

This is a test used by alternative or complementary health workers. The device used for this in vivo test is made up of a galvanometer that measures the activity of the skin at designated acupuncture points. The patient holds the negative electrode in one hand, while the positive electrode is pressed upon the points. Vials of food extracts in contact with an aluminium plate are also within the circuit. A drop in electrical current is diagnostic of an allergy to that particular food. There is no clearly described theory behind the procedure, and furthermore no clinical or scientific evidence that electro-dermal testing can diagnose food allergy.

Unproven and inappropriately applied tests

Some diagnostic procedures are particularly associated with certain conditions and certain methods of practising. One such group of clinicians are those who work within the field of clinical ecology, involved in the diagnosis of idiopathic environmental intolerances. There are also alternative or complementary practitioners who diagnose food allergy or intolerance in a variety of ways. A thorough review of the most prominent of these practices has been published by The Royal College of Physicians.26

Past medical and drug history

The possibility of a psychiatric history should be considered. Some clusters of symptoms at presentation are more likely to be linked with psychiatric diagnoses. People presenting with multiple symptoms, and concerns over many foods and other environmental problems, have been shown to be more at risk of symptoms of depression or anxiety.10 Parents may make claims of multiple food allergies in their children. Such claims have been known to be sufficiently extreme to be diagnosed as Munchausen's by Proxy.11

Interpretation of skin tests

Those without symptoms but with positive skin prick tests may lie in one of two groups. They may indeed be false positives, and the positive reaction may be due to irritants or other mast cell secretagogues and not an indication of specific IgE. The other group includes the asymptomatic but skin prick test positive people who are at greater risk of developing allergic symptoms, but not necessarily food allergies, later in life. This is termed 'latent allergy'.27

Assessments of specific IgE via skin prick tests or in vitro methods

The use of skin prick tests and in vitro identification of specific IgE is discussed later in this chapter. Such tests are usually insufficiently sensitive or specific to be used in isolation for the diagnosis of food allergies. It is suggested that the only reason for not proceeding to DBPCFC is if there is strong suspicion that a likely food substance caused an anaphylactic reaction, and positive evidence of specific IgE. Open challenge and if necessary DBPCFC should follow negative skin prick tests. Positive tests in the presence of non-life-threatening symptoms should be followed with a DBPCFC.

Mechanisms of oral tolerance

Oral tolerance is very much the norm. The reason why we are not all allergic and intolerant when we eat food is due to basic mechanisms that function in the development of our tolerance. Food intolerance and food allergy is in fact a failure of oral tolerance. The existence of oral tolerance has been known for a long time, but its mechanisms are still not fully understood. A number of experimental models have been used to demonstrate this phenomenon. One such example is the oral tolerance to ovalbumin in mice. This was induced by a single administration of ovalbumin and a demonstration of suppression of cellmediated immunity.23

Maternal intervention

Using the endpoints of clinical food reactions and immunological sensitisa-tion, there is no evidence from the available studies (Table 10.15) to suggest that dietary restriction in pregnancy reduces the risk of the infant developing adverse food reactions, in either normal or high-risk subjects. One study has suggested a possible protective effect of maternal peanut avoidance in pregnancy and lactation in an atopic population (Hourihane and Kilburn 1997). This study was Table 10.15 Prospective randomised studies assessing the effect of maternal dietary intervention in pregnancy and lactation on the development of adverse food reactions subjects food reaction Table 10.15 Prospective randomised studies assessing the effect of maternal dietary intervention in pregnancy and lactation on the development of adverse food reactions Using eczema as the endpoint, which of course may or may not be associated with adverse food reactions, a number of studies in atopic populations using maternal...

Immunological markers

The role of cord blood total IgE as a marker for the development of food allergy is not clear. Studies do not consistently show a positive association (Dean 1997, Kjellmann et aJ. 1988, Kulig et aJ. 1999). Furthermore, in the recent German multicentre allergy study where an association between cord blood total IgE and sensitisation to foods at one year of age was found, the authors comment on the poor predictive performance of cord blood IgE (Kulig et aJ. 1999). This study puzzlingly also showed that an elevated cord blood total IgE was a significant protective factor for early-onset atopic eczema (Edenharter et al. 1998). Thus, cord blood total IgE is an unhelpful marker in predicting the development of food allergy and in planning appropriate prevention strategies. Prenatal sensitisation with antigen-specific IgE has been reported but seems to be uncommon, and limited to cows' milk (Businco et al. 1983, Host et al. 1992). It is therefore unlikely to play a role in the vast majority...

Implications of study design

In deciding on which study to use to estimate the prevalence of food allergy statistical, practical and financial constraints must be considered. The ideal sample would include all the individuals in the population but this is clearly impossible and our studies must be conducted on a subset of the total population. It is this down-sizing that leads to important methodological problems due to the selection procedures. The different types of study described below represent different selection procedures and give rise to different problems. It is impossible to obtain a subset that completely represents the entire population from which it is derived. Many reports about food allergy have been based on personal series derived from general clinics or tertiary clinics. Such series are unable to provide any information about incidence and prevalence in a population as there is no known denominator associated with the data. Nevertheless, such series provide useful qualitative information about...

Approach to food avoidance

Agranulocytosis Algorithm

Once the diagnosis of food allergy or intolerance has been made, avoidance of the offending food (or foods) is the most important treatment.5 The diagnosis of food intolerance is not always easy, as patients often tend to blame foods for many symptoms that are both related and unrelated to food and there is no test which can reliably exclude or confirm the condition. The approach to management of food intolerance depends on the clinical situation (Fig. 5.1). Confirmed food intolerance If the history is highly suggestive of food allergy or intolerance, for example where an acute reaction has occurred immediately after ingesting a food, further confirmation may not be required. The suspected food should be excluded from the diet. If the subject is highly allergic, small amounts can produce severe, and even fatal, allergic reactions.3 A dietitian is best placed to give explanation and suggest alternatives. Prophylactic pharmacotherapy, if needed, should also be prescribed. Highly atopic...

Types of foods available

Allergic reactions require large protein molecules (antigens) to stimulate the production of antibodies. To reduce allergenicity, the source protein can be broken down into small peptide molecules and amino acids by enzyme hydrolysis. This process has been used successfully in the production of hydrolysed formulae (HF). These infant formulae are based on animal or vegetable protein (casein, whey, soy and bovine collagen) and are used extensively in children with cow's milk allergy or intolerance. In gluten-induced enteropathy a specific protein (gluten) is responsible for stimulating the immune reaction. Foods have been prepared without gluten, that are suitable for these individuals. When a protein is denatured by heat, most of the original tertiary structure is lost, so that many of the sites recognised by antibodies on the native molecule are destroyed. There are many examples of allergenicity being reduced, but not eliminated, by heating. Thermal processing can be part of a...

Diet and behaviour problems

In children, food intolerance has been implicated in hyperactivity or behaviour disorders. It has been claimed by some that children's behaviour improved on a food diet containing few or no additives. Parents often strongly believe that food additives, especially azodyes (e.g. tartrazine), are responsible for the child's behaviour. However, scientific proof is lacking and studies have not been able to prove conclusively the effectiveness of the dietary approach. There are considerable problems in subjecting children to a restrictive diet where behaviour problems already exist. At the current state of knowledge, a dietary approach is not recommended for this common problem.

Gastrointestinal symptoms

Diarrhoea, vomiting and abdominal colic are common manifestations of food intolerance but may also be due to infective or other causes. The cause should be established by appropriate investigations. Food intolerance causing gastrointestinal symptoms could be due to enzyme deficiency and immunological and non-immunological reactions to foods. Cow's milk intolerance is a common problem during infancy that can be treated by excluding cow's milk from the diet. Replacement with soya milk or hydrolysed formula is given. Secondary lactose deficiency is relatively common following gastroenteritis, which is self-limiting. Avoidance of milk and milk products is essential during this period. In adults, some cases of irritable bowel syndrome may be due to food intolerance. If one or more foods is suspected this can be excluded from the diet and the response observed.

Fruits and vegetables

Table 10.7 Epidemiology of adverse food reactions to wheat - key studies Table 10.8 Epidemiology of adverse food reactions to fruit and vegetables - key studies In contrast to the minor reactions of early childhood, IgE-mediated reactions occur later, so that up to 75 of IgE reactions to fruits and vegetables have their onset after two years of age (Crespo et al. 1995). In an allergy clinic based study, fruits and vegetables were responsible for the vast majority of IgE-mediated food allergy presenting after the age of ten years (Kivity et al. 1994). Many of these later childhood reactions occur in a subgroup of children with pollen sensitisation resulting in cross-reactivity to a range of fruits. This food allergy presents as a contact allergy with oral symptoms, known as the oral allergy syndrome, and occurs mainly with raw fruit or vegetables. The prevalence of allergy to different fruits and vegetables varies with the type and amount of pollen present, which determines the...

Information for industry

The Food Allergy Research and Resource Program (FARRP) at the University of Nebraska provides analytical services, information and training to the US food industry on issues related to food allergy. Many of the organisations listed above under 'Publications, CD-ROMs and training materials' have websites on the Internet, which provide background information on food allergy as well as details on their services to industry.

Employees and visitors at manufacturing locations

In addition to the risks associated with products containing allergens, risks also arise to personnel who themselves are allergic to certain ingredients and who are employed at, or visit, specific manufacturing sites where these ingredients are used. All employees should complete a pre-employment questionnaire and medical to ascertain whether any suffer food allergies and particularly anaphylactic reactions. Those that do suffer should not be expected to work in areas where allergens to which they react are processed.

Comparison of allergen contents of different foods or food sources

ELISA with a standard curve provides information on quantities of specific allergens. Sometimes it is necessary to compare one extract with another to determine if the allergens present are the same (homologous) or different (heterologous). This is useful for determining if a particular treatment reduces or increases the allergenicity of a particular food source, for example whether hydrolysis has removed cow's milk allergens from infant formula. It is particularly useful for determining if a food causing an allergic reaction was contaminated or contains cross-reacting proteins with another known allergen, e.g. a food containing hazelnuts that caused a reaction in an individual with peanut allergy. Figure 7.3 shows a schematic representation of an ELISA inhibition to determine the similarity of two allergenic food sources. This assay may also be adapted to provide quantitative data where the percentage inhibition obtained with dilutions of a homologous antigen to the one bound to the...

Geographical variations

Data concerning the incidence of adverse food reactions from different countries may shed some light on factors that might be important in the development of adverse food reactions. These factors include genetic, cultural, dietary and other environmental differences. Unfortunately all the cohort studies are from Europe, Australia and the USA, with no comparable data from other countries. However, there are case series from these other countries that allow comparisons to be made between foods that are important in causing adverse reactions in different countries.

Introduction the range of treatments

Treatment of food intolerance is primarily by elimination of the food from the diet. This may be a difficult task for a number of reasons. It may not always be possible to identify the foods responsible for the symptoms. Some foods are consumed so frequently that simple elimination without adequate replacement may lead to nutritional deficiencies. Other foods, such as egg and nuts, may be hidden in prepared foods such as cakes and biscuits, and occasional inadvertent exposure may occur.

The legal background the Food Safety Act 1990

Since the days of Magna Carta there have been controls over the sale of food in one form or another. The right to 'one measure throughout the land' was an early example of this. Since that time there have been legal controls to prevent the adulteration of food. Flour and milk were early examples, to prevent the addition of chalk to flour (later required by law to boost the calcium content), and to prohibit the addition of water to milk. Since that time the technology of food and the structure of our society has become infinitely more complex. As a consequence issues which once constituted clear breaches of the law are now less easy to discern. We are now in a situation of needing to exercise judgement in order to decide whether or not a situation which may be prejudicial to some will actually give rise to an offence, or whether some other course of action may be open to the consumer. In examining the issue of food intolerance, we need to ask ourselves whether food which may be...

Avoidance and elimination diets

An assessment should be made of the severity of the reaction, which gives an indication of the strictness of the recommended avoidance regimen. If the symptoms are severe and life threatening, complete elimination of the food is mandatory. Less severe symptoms may allow some degree of flexibility. A detailed explanation is essential for successful avoidance. Egg, milk, soy and nuts may be hidden in other foods and reading the ingredient list is essential. Alternative food should be suggested and it is essential to make sure that the avoidance diet is nutritionally adequate. A complete dietary history is of utmost importance and may uncover important sources of allergenic foods such as milk. It would also allow the caring physician dietitian to suggest alternative foods with equivalent nutritional value. For example, soya milk or hypoallergenic formulae can be given for cow's milk intolerance during infancy. The services of a qualified dietitian are extremely useful.

Gastrointestinal reactions

Gastrointestinal reactions to foods are very common and not all are associated with positive results on standard tests. A severe feature of food allergy in childhood is called eosinophilic enterocolitis, where the lining of the bowel is filled with cells called eosinophils, which are major factors in local allergic inflammation and reactivity. Patients, usually less than two years old, have severe abdominal pain and bloody diarrhoea, usually made worse by several foods. The treatment of this is the same as for food-related anaphylaxis, i.e. allergen exclusion. In many cases multiple allergens may need to be excluded, and enterocolitis can be a very difficult problem to treat.33

Sources of further information and advice 691 Consumers

'Free-from' lists covering own-label products are available from Waitrose, Sainsbury, Tesco and Safeway. These lists cover the standard ingredients covered by the UK Food Intolerance Databank, plus peanut and nuts. Asda contributes data on its own-label products to the UK Food Intolerance Databank. There are a number of self-help groups that offer information and advice to sufferers. In the UK, the British Allergy Foundation and the Anaphylaxis Campaign are among the most important. The British Allergy Foundation provides information, advice and support to allergy sufferers, including a helpline, a regular newsletter and leaflets. The Anaphylaxis Campaign works to raise general awareness of severe food allergies and provides general advice and a video on anaphylaxis, as well as producing a quarterly newsletter. In the United States, the Food Allergy Network provides a wide range of assistance for food allergy sufferers, including general advice, product alert information, plus a video...

European countries that successfully set up new databanks

Greece was the first partner of the project to set up its food intolerance databank, in August 1996. The databank is run by the Technological Educational Institution (TEI) of Thessaloniki and covers eight food additives and ingredients milk, egg, gluten, wheat, soya, sulphur dioxide, benzoates and azo colours. The databank is updated annually and currently they have approximately 400 products listed from 25 companies. The Technical University of Graz (Erzherzog Johann Universitat) established the Austrian Food Intolerance Databank in October 1996 with the financial assistance of the Austrian Ministry of Science. This databank covers 11 ingredients and additives milk protein, lactose, peanut, soya, wheat, gluten, egg, fish, benzoate, sulphur dioxide, and azo colours. The databank now has 19 contributors, with a total of 1600 products entered. Two other participants in the project - Belgium and Denmark - launched their food intolerance databanks shortly after the end of the project...

Summary trends in treatment

Despite recent advances in our knowledge of immune processes involved in food allergy and intolerance, there have been few major developments in the treatment of this common condition. Avoidance of the offending food remains the mainstay of treatment. Pharmacological therapy is useful in acute reaction due to inadvertent exposure but generally disappointing in the treatment of chronic food intolerance. The importance of a detailed history cannot be overstated. The diagnosis can often be made on the history alone. A dietary history helps to identify the consumption of the offending food and aids in suggesting replacement. Patients with a history of acute allergic reaction to foods such as milk, egg, fish or nuts have to be extremely careful in consuming packaged food or when eating out. Packaged foods should be labelled clearly with the highly allergenic foods to reduce avoidable morbidity and mortality. In children with cow's milk intolerance, the development of relatively safer...

Specific immunotherapy

Several studies evaluating the effectiveness of specific immunotherapy in food allergic diseases such as peanut and fish allergy produced conflicting results. The majority of the studies did not find evidence of protection in peanut allergic patients, and severe reactions during the treatment were common. However, some studies have supported the use of immunotherapy in the treatment of fish and egg allergy. The overall consensus is that specific immunotherapy has no place in the treatment of food allergy.

Other international databanks 651 South Africa

The South African Food Intolerance Databank (FIDB) was initiated in 1990 by the Grocery Manufacturers Association in South Africa, which modelled the databank on the UK system. In 1995, the Association for Dietitians in South Africa (ADSA) took over responsibility for the project and subsequently produced The South African Free From Handbook of Food Products, a single book listing free-from information in tabular form. The project was supported by a large number of institutions in South Africa, including the Department of Health, Food Legislation Advisory Group, Consumer Services Board and two coeliac groups. Originally, access to the book had been restricted to medical professionals only, and, although the book was largely distributed by dietitians, it was later made available to the general public through bookshops. The databank covered ten ingredients and additives milk, lactose, egg, soya, wheat, rye and gluten, benzoates, sulphur dioxide, BHA and BHT, glutamates and tartrazine....

Careful history

Positively incriminated cause symptoms within hours of ingestion (except protein-sensitive enteropathies). Some patients may give very specific symptoms that have measurable parameters, useful as outcome measures of the DBPCFC. Respiratory symptoms can be monitored using pulmonary function tests and bronchial provocation challenges. Peak expiratory flow rate (PEFR) and the forced expiratory volume in one second (FEV1) are the most reproducible measures affected during bronchoconstriction (narrowing of the airways). Specific bronchial provocation challenges can be useful in the diagnosis of food allergies. These have been employed particularly in the confirmation of occupational or industrial asthma. Specific bronchial challenges, using aerosol preparations of the implicated allergens, can be used to demonstrate resultant bronchoconstriction.22

Novel treatments

Peptides have been synthesised which are able to bind to the IgE receptors. This will competitively inhibit IgE binding to the receptor. These peptides, therefore, have the capacity to block IgE-mediated reactions non-specifically. They may be useful in patients with multiple food allergies or other IgE-mediated diseases such as asthma and rhinitis. Several such peptides are in the developmental phase. A novel method of blocking the IgE-mediated reactions is to develop monoclonal antibodies to the IgE molecule. These anti-IgE antibodies bind to the free IgE in the circulation, thus reducing the available IgE to bind to mast cell receptors. In clinical studies, anti-IgE antibodies have been found to be useful in allergic asthma and several large-scale studies are being conducted. It remains to be seen if anti-IgE antibodies will be useful in food allergic disorders such as peanut, egg and cow's milk allergy.

The 25 rule

Manufacturers recognise the importance of providing information on the ingredients list to help sufferers of food allergies to select a suitable diet with confidence. To do this the list must accurately reflect the ingredients in the product, including those allergens that are present in minute amounts. Consequently, the majority of manufacturers voluntarily ignore the exceptions to the law and voluntarily label the presence of all allergens on the ingredients list. This includes carriers of ingredients, constituents of compound ingredients, and ingredients that may be present through cross-contamination that are on the list of key allergens.

Coeliac disease

Coeliac disease deserves a special mention. When discussing this lifelong condition, it is essential that it is not confused with classic food allergy. Allergic reactions usually occur within seconds or minutes of contact with the offending food, or occasionally within hours, whereas coeliac disease rarely causes such an acute, immediate reaction. This is an important distinction, because there is a danger that food companies may place gluten traces in the same danger category as nut traces, with the result that they fall to the temptation of adopting 'may contain' labels. There have certainly been cases where a trace of gluten makes a coeliac unwell, but such cases are not fatal.

Associated morbidity

Markers of atopy as a whole are associated with an increased risk of developing adverse food reactions. Thus asthma, eczema and rhinitis are increased in children with food allergy compared to the general population (Zeiger and Heller 1995, Hide et aJ. 1996). The strongest association is between eczema and food allergy, and the risk appears to be greatest in infancy and in those with moderate to severe eczema (Burks et aJ. 1998, Sampson 1996). The literature appears to be best for peanut allergy. One study found that in peanut-allergic children atopy in some other form was present in up to 96 of subjects (Ewan 1996). In the Isle of Wight birth cohort study half of the children with peanut allergy had asthma and two-thirds had eczema, considerably higher than the rates in the cohort as a whole (Tariq et aJ. 1996).

Genetic factors

If either parent has a history of an allergic disease then siblings are at increased risk of developing allergic disease, which includes eczema, asthma, allergic rhinitis and food allergy (Zeiger and Heller 1995). The risk is greater if either parent is atopic, and increases if both parents are atopic. In children with cows' milk allergy, a family history of atopy in first-degree relatives has been found in 23-80 of cases (Goldman 1963, Ventura 1988, Host 1990). Findings from a Danish study looking at skin reactions to foods are presented in Table 10.14, confirming the association of food allergy and family history of atopy (Kjellman 1983). A family history of food allergy in a first-degree relative increases the risk of food allergy approximately fourfold in other family members (Dean 1997). In families with at least two food allergic individuals, the same food is frequently implicated. The best-studied food is peanut whereby if one sibling has peanut allergy then the risk of another...

Infant intervention

There are large variations between the studies comparing the different milks, namely breast milk, soya, hypoallergenic formulae (partially or extensively hydrolysed cows' milk), and cows' milk formulae given to the infant and the development of allergy. Many of the studies have looked for effects of the type of infant milk feeding on the development of allergic respiratory or skin disease, rather than on food or immunological (skinprick specific IgE) reactions. A number of the early studies attempting to look at the impact of the infant milk formula on the risk of developing adverse food reactions showed a marginal reduction in skin test reactions and clinical adverse reactions to cows' milk (Hamburger 1984, Host et al. 1988, Saarinen and Kajosaari 1995). However, many were not randomised or prospective in their design. The more recent studies which attempt to look at the impact on adverse food reactions are randomised (Table 10.16) and use food challenge and skinprick specific IgE...


The examination of the patient suspected of having an allergy to a food then focuses upon the presence or absence of signs associated with other atopic diseases. This not only establishes whether the individual has an atopic disposition, but also may identify signs resulting from, or exacerbated by, their food allergy. Patients with perennial or seasonal rhinoconjunctivitis may have injected conjunctivae (visible small blood vessels), erythematous conjunctivae (reddened whites of eyes), puffy eyelids, and erythematous, oedematous nasal mucosa (the lining of the nose appearing swollen and red). Studies investigating any link between food allergy and otitis media with effusion (sometimes termed glue ear - long-standing fluid in the middle ear resulting in, albeit temporary, conductive hearing loss) have been poorly conducted.18 To date, there is no good evidence linking this condition with food allergy.


Eczema can be part of a late phase IgE-mediated reaction or a delayed immune reaction to allergen, not mediated by IgE. Eczema is a common feature in people who do not have positive skin prick tests or IgE tests to the allergen. It is therefore only on the basis of a clinical improvement on exclusion of the food and relapse on reintroduction that the diagnosis can be made. Usually the only clinically useful test is an exclusion diet. Patch testing is being investigated as a diagnostic tool for food allergy, particularly in children.32

Atopic eczema

Eczema is a chronic disease and improvement with exclusion diet may not occur immediately. An open challenge should always be undertaken if an improvement has been observed to confirm the causative relationship. Doubleblind challenge may not always be feasible in clinical practice. Once the food(s) are identified, a longer period of dietary avoidance is undertaken. Cow's milk could be replaced with soya milk (if the child is not allergic to soya) or hydrolysed formulae. Supervision of a qualified dietitian is recommended to ensure compliance and nutritional adequacy of the diet. As food allergy and eczema improves during early childhood, an open challenge may be undertaken every 6-12 months depending on the severity of eczema and results of the skin test or RAST.


In the treatment of food allergy, antihistamines are given primarily to relieve symptoms such as itching and urticaria due to inadvertent exposure. Oral symptoms, such as itching in the mouth and throat and swelling, may also respond but there is little effect on gastrointestinal symptoms such as vomiting and diarrhoea. For mild symptoms, oral antihistamine may be effective and may be continued until symptoms disappear. For moderate to severe allergic reactions, antihistamine should be given through the parentral route for rapid systemic availability. Occasionally antihistamines are used regularly for chronic food allergic symptoms where causative food(s) have not been identified.


This chapter has aimed to give some background to the history of food intolerance and food allergy. Hopefully it has shown that food allergy and intolerance is a condition that has existed for centuries, although it may not have been labelled as such. This was followed by a section on terminology from which the reader will recognise that the debate still continues. Although the recommendations of the European Academy of Allergology and Clinical Immunology (EAACI) are outlined in the chapter, it is likely that readers will come across other terms or indeed, more commonly, will find these terms being used in different contexts. In time, no doubt, a worldwide terminology may evolve, but for the time being clarification and definition have to be offered in the literature. The sections which followed were dedicated solely to mechanisms of food intolerance and allergy and food tolerance. It is essential to have a grasp of the current state of evidence in this area in order to appreciate...

Specific IgE

Both the appropriateness and standardisation of the allergen are important in this diagnostic test. Clinical validation depends upon sera from individuals with DBPCFC-proven food allergies. This can be problematic when developing assays for the investigation of rare food allergies.

Patch testing

Patch testing is a diagnostic tool commonly employed in the diagnosis of contact dermatitis. This may be irritant or allergic in origin. It may be difficult and even artificial to distinguish between these two. Irritants make up about 80 of the problem, and an allergic cause can be attributed to about 20 of patients with contact dermatitis. It is rarely used in the investigation of systemically induced food allergies.12 Patch testing infants suffering from eczema with cow's milk may hold some diagnostic promise.1

Food challenges

People seem to be very ready to attribute many symptoms to either a specific food or a range of foods. Studies suggest that at most 50 of patients suspected of having a food hypersensitivity will have a positive double-blind placebo-controlled food challenge.20 This statistic is from selected populations derived from allergy clinics. These people are almost certainly at higher risk of definite food allergy than an individual selected from the general population in a more general clinic, because of prior 'selection' based upon history and examination. The 'placebo effect' of many foods is strong and has been demonstrated in many studies comparing the results from open (unblinded) tests with those from blinded ones.20 The placebo effect is applicable to both patient and investigator alike, underlining the importance of blinding both investigator and patient. There is also a therapeutic as well as a diagnostic role for food challenges. This is best illustrated in children. Infants with...

Further reading

Food and Drink Federation, Food Allergens Advice Notes, FDF, London, 1998. Institute of Food Science and Technology, Food and Drink Good Manufacturing Practice - A Guide to its Responsible Management, IFST, London, 1998. Jardine N J (ed.), Food Allergy and Other Adverse Reactions to Food, International Life Sciences, 1994. Lessof M (ed.), Food Allergy Issues for the Food Industry, Leatherhead Food

Laboratory tests

Double-blind placebo-controlled food challenges remain the 'gold standard' in the diagnosis of food allergies, but in vitro tests can supplement this. Nearly all current diagnostic knowledge lies within the area of Type I, IgE-mediated mechanisms of food allergy. This is the only conclusively proven aetiology of food allergy.


When reading different texts in this area, it becomes evident that in the medical and scientific community, there is no single global consensus on what is food allergy and what is food intolerance. For example, there are authorities who consider coeliac disease as a type of food allergy and others who regard it as a form of food intolerance. Some may not consider it as either. Indeed, it appears that it all depends on what definition one has used. The terminology which appears to have gained credibility amongst many peers is that adopted by the European Academy of Allergology and Clinical Immunology (EAACI).1 The distinguishing feature of this terminology is that it is based on mechanisms rather than clinical symptoms. The structure of this terminology is outlined in Fig. 1.1. Broadly, adverse reactions are divided into toxic and non-toxic reactions.

Ingredients covered

The UK Food Intolerance Databank currently covers the following ingredients and additives milk, egg, wheat, soya, BHA and BHT, sulphur dioxide, benzoates and azo colours. The list is, however, under regular review. For example, in light of recent concerns about peanuts and peanut oil, the possibility of including information on peanuts has been discussed. The main problem in adding a peanut or nut category concerns the severity of reactions to minute quantities of peanut or nut and a belief by many food manufacturers therefore that this information should not be released to a third party. By restricting circulation of free-from peanut lists to named customers, a company is able to notify the individuals directly if there is a recipe change or contamination problem. Future developments planned for the databank, however, may make inclusion of nuts and other allergens in the Food Intolerance Databank possible.

Other initiatives

The Ministry of Agriculture, Fisheries and Food has prepared a list of guidelines for catering establishments to raise awareness of the issue of food allergies and to help caterers provide information for sufferers. This is equally applicable to small retail environments. An extract from the recommendations is provided in Fig. 8.3.


Hydrolysed casein and whey infant feeding formulas have been developed with the aim of reducing symptoms of milk allergy in infants. However, allergic reactions have occurred in some infants fed with these formulas, so tests have been developed to estimate residual activity. Hydrolysis is aimed at destroying the allergenic epitopes by cleaving the protein molecules into peptide fragments. Some are extensively hydrolysed and filtered, and it is becoming apparent that only these reduce the risk of atopic sensitisation.


Oral sodium cromoglycate may be useful in some patients with multiple food allergies.12 It is a less effective but safer alternative to steroids in the management of chronic food allergy not responding adequately to food allergen avoidance. However, it should not be used in place of allergen avoidance. Acute symptoms such as bronchospasm, rash, nausea and diarrhoea respond better than do chronic food-related diseases such as atopic eczema. Side effects are minimal, although nausea, rashes and joint pain have been reported.


Drug treatment is of value in acute allergic reactions, as unintentional ingestion of the food may occur. The need for pharmacotherapy depends on the sensitivity to the allergenic foods and severity of the resulting symptoms. Those who are highly sensitive, for example, to peanut, may react to minute amounts of peanut proteins hidden in the packaged food or food contaminated by peanut during preparation. Despite taking extreme care, total elimination cannot be guaranteed. This leads to significant morbidity and mortality. Early treatment with adrenaline may be life saving. Drug treatment for patients with chronic food allergy and intolerance is not rewarding. Several drugs have been tried but the results are disappointing. Patients with multiple food allergy or intolerance are at a particular disadvantage, as avoidance is difficult and may lead to nutritional deficiencies. For this reason the diagnosis of food intolerance should only be made after careful consideration of history,...

Brand extensions

Many brand names are now used across a wide variety of products for example, a chocolate bar brand may be used for a dessert, ice cream, drink, chocolate spread, Easter egg, and various shapes and sizes of chocolate bars. It is possible that individuals with a specific food allergy and for whom the original chocolate bar is acceptable may assume that the other products sold with the same brand name are also suitable for their diet. However, in most cases different products will contain different ingredients, be manufactured on different production lines, in different factories, using different technologies and may well contain different allergens from other products under the same brand. It must be stressed that each product needs to be assessed on its own merits by the consumer by checking the ingredients list on the label. The onus is certainly on the consumer to check the suitability of each product for their particular diet.

Hurdles to overcome

In addition, there was found to be a variation in the legal liability between the different EC countries if a product was incorrectly declared as 'free from'. In most countries, there is no obligation to inform consumers who suffer from food intolerance of the presence or absence of potential allergens in food, but if the manufacturer chooses to inform the consumer he will be liable for the information provided. The liability for injuries and negligence were the elements most likely to vary in different Member States. There was also a significant increase in awareness of food allergy and intolerance over the course of the project. As a result, the Codex Alimentarius started discussions on the Proposed Draft Labelling of Allergens that can Cause Sensitivity (Alinorm 95 22). The prospect of potential mandatory labelling of allergens in the future delayed and, in some cases, led to a cessation in the establishment of food intolerance databanks in certain countries. This was due to a...