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Dealing with Food Allergies
A Practical Guide to Detecting Culprit Foods and Eating a Healthy, Enjoyable Diet
By Janice Vickerstaff Joneja
Bull Publishing CompanyCopyright © 2003 Janice Vickerstaff Joneja
All rights reserved.
WHAT IS FOOD SENSITIVITY?
Our bodies are like complex factories that function day and night without pause in a never-ending cycle of renewal and decay. New cells and tissues are created, old worn-out matter is broken down, recycled or excreted, and our organs continue to function, day in and day out, without requiring any direction from us. We provide the building blocks and the source of energy for these processes through the food we eat, the liquids we drink, and the air we breathe. Everything runs smoothly in its appointed manner until a glitch in the system creates havoc, and we then have to deal with the consequences of this malfunction.
Food allergies and intolerances are just one example of "things going wrong," but because we cannot stop eating, we can't ignore the signs. We must come to terms with how our body is acting and take steps to adjust to the situation. In making changes, especially ones as far-reaching as how we eat, we need to understand exactly what we are trying to achieve so that we can make the correct modifications and then stay with them. So this book, which will guide you through the complexities of eating in the way that your particular system requires, even when food seems to cause nothing but problems, is going to start by answering that really important question: What is happening when my body rejects food?
We cannot avoid a discussion of science. In order to understand what happens when things go wrong, you need to know how your body functions normally. Section I will take you step by step through the processes of immunology, biochemistry, and physiology that are involved when your body reacts adversely to food. Don't be dismayed by the seemingly overwhelming science — each step leads logically to the next, and each is explained in a way that will help you understand. Any terms that seem obscure will be found in the Glossary (page 463) — use this as a dictionary until you become familiar with the terminology.
Perhaps the most important concept that you will learn in this section comes as a surprise to many people: Food does not cause allergy or intolerance reactions! Food in itself is harmless — it cannot cause disease. It is our body's response to the food, or more accurately, something in the food, that causes the symptoms we experience. Even when food is poisonous, it is so because our bodies lack the resources to detoxify the material (a biochemical process).
An allergy is caused by our immune system reacting to a foreign material (food) that is incapable of causing disease on its own. In the process of rejecting the "foreign material," the immune system releases chemicals that cause the symptoms we call allergy. In other words, a food allergy is a rejection of the food by our immune system that can sometimes be quite devastating in its severity. In contrast, intolerance of a food is often due to an error in the way our bodies process it, not an actual rejection of it. Food intolerance reactions are usually milder than allergies and do not involve the immune system.
Food allergy is perhaps one of the most confusing and misunderstood conditions in medical practice. Physicians, other health care professionals, and patients alike are often unsure about what symptoms are caused by food allergy, how it is diagnosed, and what is the best way to manage it. The greatest obstacle in understanding the problem is the misconception that "food allergy" is a distinct disease. In fact, "food allergy" refers to a response of our bodies that can result in many different symptoms, in diverse organ systems. Furthermore, a food that causes symptoms in one person is often quite harmless when eaten by another.
It is standard medical practice that when a person develops symptoms, his or her doctor orders specific tests in the process of making a diagnosis. When the doctor has made the diagnosis, he or she will then recommend a treatment, which in most cases will control the disease. In the case of food allergy, the only time the specific cause can be easily identified is in the occurrence of anaphylaxis: when a specific food triggers an immediate and sometimes life-threatening response. However, unlike a specific medical condition in which the same cause in different people causes the same disease, the food that causes anaphylaxis in one person rarely causes the same symptoms in others. The symptoms are caused by the allergic person's unique response to the food, not by the food itself. For example, an infectious bacterium such as Salmonella will cause the symptoms of severe food poisoning in just about everyone who eats the contaminated food. In contrast, a person who is highly allergic to peanuts can develop life-threatening anaphylactic shock after consuming the smallest quantity of food, whereas the majority of people can eat a whole bag of peanuts without any ill effects.
To complicate the situation further, most adverse reactions to foods are not caused by an allergic reaction, but by "food intolerances." Food intolerance reactions are quite different from food allergy both in the way the body responds to the food and in the management of the condition. The term we often use to describe the situation in which eating a food results in distressing symptoms is food sensitivity. This term covers both food allergy and food intolerances and is often used in place of both, or when it is unclear whether the condition is an allergic reaction or a food intolerance.
The term food allergy is reserved for a response of the immune system that is triggered when a food is eaten by a person who has been sensitized to it. Sensitization is the process whereby the immune system is alerted to something foreign entering the body, which it believes to be a threat to the body's health. Thereafter, whenever that same foreign material enters the body, the immune system responds by releasing its "weapons" to destroy the foreign invader. This is the usual way in which the immune system protects us from diseases such as viral and bacterial infections. All of the food we eat comes from foreign plants and animals, so it is not surprising that sometimes this foreign material is mistakenly identified as "alien" to the body. In fact, what is more surprising is that most of us can eat this foreign material without our immune systems responding at all! This process, called "tolerance," will be discussed in greater detail in later chapters. Figure 1-1 illustrates the ways in which our bodies can respond to food: tolerance or allergy.
How the Immune System Responds in an Allergic Reaction
The key event in food allergy occurs when the immune system identifies a specific food as a foreign invader and orders the release of special chemicals to protect the body. These chemicals act on body tissue and result in a specific set of symptoms. In the 1960s, all reactions of the immune system that are not involved in protecting us from diseases caused by viruses, bacteria, and similar threats to the body were termed "hypersensitivity reactions" by the internationally renowned Professors Gell and Coombs. Such reactions include allergy. Therefore, another term for an allergic reaction is a hypersensitivity reaction, which is often used in medical texts in place of "allergy." (On a personal note, I was greatly privileged to learn my first immunology under the tutelage of Professor Gell, who was chairman of the university department where I was a student, and his distinguished colleagues.)
In contrast, any adverse reaction to a food or food additive that is not caused by a response of the immune system is called food intolerance. Because there are many ways in which food can cause symptoms in the body that are not due to an immunological (related to the immune system) response, the term covers a large number of different physiological mechanisms. For convenience, we shall refer to adverse reactions to food as "food sensitivity" when it is unclear whether the reaction is an allergy or an intolerance.
How Common is Food Sensitivity?
It is difficult to determine how many people are actually sensitive to foods and suffer symptoms as a result of eating or drinking. The absence of any reliable laboratory tests that can prove a person is allergic or intolerant to a specific food or food additive makes estimating how frequently such reactions occur very difficult. Because there are so many different immunological and nonimmunological reactions involved in food sensitivity symptoms, it would be unrealistic to expect that a single laboratory test could identify them all. The only accurate way that clinicians can determine a person's reactivity to a food, beverage, or food additive is by eliminating the food from the diet, followed by challenge (reintroducing the food) under conditions in which neither the doctor nor the patient knows whether he or she is eating the test food or the placebo (sugar pill). This is known as the double-blind placebo-controlled food challenge (DBPCFC). Unfortunately, this process is too expensive and time-consuming to be a routine procedure. However, based on the statistics that are available, it is usually accepted that food allergy occurs in up to 8% of children under the age of five years, and that 2% of children in this age group have an allergic reaction to cow's milk proteins. Most children outgrow their food allergies by the age of five years, and allergy in adults is relatively uncommon. Most authorities estimate that less than 2% of adults have true food allergy; some consider the figure of less than 1% to be more accurate. However, intolerance (non-immune-system related reactions) of food components, naturally occurring chemicals, and food additives is a frequent experience, and some practitioners estimate the incidence of food intolerance to be as high as 50% of the adult population.
Symptoms of Food Sensitivity
Symptoms of food intolerance usually appear in three major organ systems: the digestive tract, the respiratory tract, and the skin. In the digestive tract, nausea, vomiting, cramping pain, diarrhea, abdominal distension (bloating), and excessive gas are common indicators of food allergy. In the respiratory tract, sneezing, nasal congestion (stuffy nose), runny nose, itching and watering of the eyes, itching in the throat, throat tightening, wheezing, shortness of breath, and chest tightening might be signs of allergy. Skin reactions include eczema, hives, facial swelling, and rashes, especially with itching. These symptoms might occur after eating the food, or when the skin and mucous membranes come into contact with allergens. An allergen is the term we use to indicate the component of the food or other material, such as pollen, animal dander, mold, or insect venom, that causes allergy. (Mucous membranes are the tissue systems in internal organs exposed to the outside, such as the mouth, digestive tract, respiratory tract and lungs, and the urogenital tract). The most common contact reactions occur on the hands and in the mouth after direct exposure to raw foods.
The most severe allergic reaction is anaphylaxis. In anaphylactic reactions to food, the response is systemic, meaning that the reaction is not confined to any single organ system. Multiple organ systems are involved, and symptoms develop rapidly throughout the body. In the most severe anaphylactic reactions, the symptoms can start within 1 to 2 minutes of eating the food. Thereafter, the reaction builds up over a period of 1 to 3 hours and it can result in anaphylactic shock and death from cardiorespiratory arrest. Fatal food anaphylaxis is fortunately very rare. Authorities have estimated that there are an average of 100 cases of fatal food anaphylaxis every year in the United States and that there are10 cases per year in Canada. Nevertheless, even one case is too many, and we must be very alert to taking the most appropriate precautions in such situations.
Foods That Cause Food Sensitivity Reactions
In theory, any food should be capable of causing an allergic reaction. All foods contain molecules capable of triggering the immune system–we call these molecules antigens. However, for many reasons that include both the structure of the antigens and peoples' immunological responses to them, the foods that cause the majority of allergic reactions tend to be few in number. We refer to antigens that trigger an allergic response as allergens.
Adverse reactions to foods and beverages can appear in many forms and can result in a confusing array of symptoms. Sometimes, the realization that a person's ill health is caused by his or her diet is reached only when all other causes have been ruled out, often after many (sometimes painful) diagnostic tests. At other times, the culprit food is instantly recognized, especially when the result is a frightening, severe anaphylactic reaction. Dr. T. J. David, a British pediatrician, summarizes the current medical attitudes towards the subject of adverse reactions to foods quite succinctly in his book Food and Food Additive Intolerance in Childhood: "Some doctors have hoped that the current popular vogue for food intolerance, if ignored studiously enough, would go away. Others are inclined to see reactions to food around every corner."CHAPTER 2
SIGNS AND SYMPTOMS OF FOOD SENSITIVITY
An adverse reaction to a food can result in a variety of symptoms and may seem quite different in different people. Some people develop hives, others have an upset stomach, while others might have a migraine headache or even an asthma attack. Some practitioners have tried to put people into categories depending on their specific target organ (the site in the body where they usually "express" their reaction). Some people are "skin reactors" and break out in hives, develop swelling, especially of the face and mouth, and itch quite severely after eating an allergenic food. Others are "respiratory reactors," who tend to develop nasal stuffiness (rhinitis), irritated eyes, and even asthma. A third group are the "headache sufferers," who develop migraine headaches or other types of headaches in response to "alien foods." The fourth group, which seems on average to contain the largest number of people, are the "gut reactors," who develop stomach pains, bloating, diarrhea, gas, and sometimes nausea and vomiting after eating an allergenic food. It is probably not surprising that this grouping of people also reflects their responses to stress — it would seem that each person has their own "weak point" and it is here that they first experience an "attack" on the body. Of course, many people have symptoms in more than one of these systems, but there is usually one that is most vulnerable.
Because of each individual's unique response, it is not surprising that food allergy is experienced in a variety of ways. This often makes diagnosis of food allergy very difficult for the doctor. After all, most medical conditions have very specific symptoms, which makes their diagnosis quite straightforward when the appropriate tests are carried out. When we are dealing with food allergy, the most common initial approach is to rule out any other cause for the patient's symptoms before suspecting food as the culprit.
When we consider the variety of foods that make up our daily diet–even when we eat only pure foods–we realize that they are all derived from plants and animals that are completely foreign to our bodies. It is quite surprising that most of us consume all of these foods without any ill effects. Humans have adapted amazingly well to the vast range of foreign proteins and chemicals that we now consume in our daily diets. The internationally renowned allergists Professors Jonathan Brostoff and Stephen Challacombe, in the preface to their encyclopedic textbook on food allergy and intolerance, point out that "the majority of us are tolerant from an immunological point of view of large quantities of foreign protein to which the body is exposed each day." However, when this tolerance is compromised, we become ill.
Excerpted from Dealing with Food Allergies by Janice Vickerstaff Joneja. Copyright © 2003 Janice Vickerstaff Joneja. Excerpted by permission of Bull Publishing Company.
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