When an individual develops symptoms from eating a food that does not normally cause such symptoms in others, then that person is described as having a food sensitivity (or sometimes a food hypersensitivity). Food sensitivities are divided into different types depending on what body system is involved in the reaction. This page will describe these different reaction types. It will also explain the importance of an accurate diagnosis and correct treatment. Additionally it will also give a brief explanation of why individualized dietary advice is important. Throughout this section for the consumer with food sensitivities, there will be links to other web pages that can provide more detailed information about the differing food sensitivity conditions and how they can be managed day-to-day.
Types of sensitivity reactions
When an individual reacts to a food they generally describe themselves as having a food allergy, but such reactions may not always be a food allergy according to its medical definition. A food allergy is when an adverse reaction to a food is due to the individual's own immune system.
Food allergies can themselves be split into different types. One type of reaction requires the presence of a certain antibody called immunoglobulin E (usually shortened to IgE). This immunoglobulin plays an essential role in food allergy reactions, acting as a 'go between' within the immune system, facilitating the reaction. These types of reactions are called IgE-mediated Food Allergies (sometimes called Antibody-mediated food allergies) and they generally occur quite soon after the food is eaten (sometimes within a minute) although some symptoms may take a few hours to appear. Thus, these reactions are also sometimes known as immediate hypersensitivity reactions. These types of reactions can cause the severe reactions to food we hear about in the news such as swollen lips and throat, hives, and/or a severe drop in blood pressure. However, they can also cause other symptoms such as vomiting, diarrhea, eczema and asthma. More information on these conditions and how to manage them can be found at the FARE (Food Allergy Research and Education) website.
Reactions where different cells of the immune system (not IgE) are involved are called Non-IgE mediated food allergies (sometimes called Cell-mediated Food Allergy). These adverse reactions to foods are not immediately life-threatening but they can still be serious. If they are not treated correctly the sufferer may become very ill. Even in cases that do not become serious, the sufferer is often in great discomfort which can become both mentally and physically draining if left untreated. Many non-IgE mediated conditions involve the digestive system (such as gastro-esophageal reflux, food protein-induced enteropathy and food protein-induced enterocolitis syndrome). Some eczema can be non-IgE mediated and a condition called Heiner's Syndrome is also a non-IgE mediated Food Allergy which affects breathing. Celiac disease is a non-IgE mediated food Allergy although it is often considered a distinct condition separate from food allergy.
Further information on food protein-induced enterocolitis syndrome (often referred to as FPIES) and other food protein induced enteropathies can be found in the separate section of this website called 'FPIES' and also from the FPIES foundation website.
There is also a separate section on Celiac disease. Additional advice and guidance can be found at the website of Beyond Celiac, formerly known as the National Foundation for Celiac Awareness (NFCA).
There are food allergies where both IgE and other factors within the immune system are required to be present and active. Such conditions are collectively called eosinophilic disorders and include eosinophilic esophagitis, eosinophilic gastritis and eosinophilic gastroenterocolitis. Details of these conditions can be found in the separate section of this website called Eosinophilic disorders and also from the website of the American partnership for eosinophilic disorders (Apfed).
Food Sensitivities not involving the immune system
These conditions are often called Food Intolerances although your Clinician/Health care worker may call them Non-Allergic Food Hypersensitivities. These conditions are not as well understood as those which involve the immune system (i.e. food allergies). They may be due to an individual being very sensitive to the pharmacological effect of some food ingredients (e.g. caffeine, biogenic amines, alcohol, or certain food additives) or they may be due to an enzyme deficiency. Conditions such as irritable bowel syndrome, rhinitis, hyperactivity, migraine, tachycardia (rapid heartbeat), and urticaria (hives) have been reported as being due to or worsened by certain types of food but the evidence for any association is not strong. On the other hand, reactions due to enzyme deficiencies are well documented and understood. The best example is lactose intolerance caused by a deficiency or partial deficiency of the enzyme, lactase, in affected individuals. The deficiency in lactase leads to an intolerance to milk and milk products that contain lactose or milk sugar.
Diagnosis and Treatment
Since the elimination of any food from the diet is difficult and can cause a nutritional deficiency (particularly in infants and young children), it is very important that any suspected reaction to a food is investigated medically. Without expert medical assistance, individuals often identify food as the cause of the symptoms when it is not or else they identify the wrong food or too many foods. This can lead to unnecessary avoidance diets. Additionally, getting an accurate diagnosis from an allergist will allow access to any appropriate medication required to manage the condition. This is particularly important in cases of life-threatening reactions to foods. In the box on the right are links to help you to further investigate your symptoms to see if they m ay be related to food sensitivity (The Virtual Allergist) and how to find an allergist.
We would recommend using these links to ensure that you see a recognized medical practitioner working in the world of food sensitivity to assure that you are getting the best available advice. Where available, a board-certified allergist (see the AAAAI web site) is often the best choice.
Whatever the type of food sensitivity, the treatment of it is the same, avoidance of the food that causes the reaction. The extent to which a food needs to be avoided and how that is best done differs according to the condition and the food to be avoided. Any dietary manipulation should not be carried out without consultation with a health professional who as well as being qualified in the field of food sensitivities, are also qualified in nutritional counselling (ideally a dietitian). This ensures you get an individual dietary management plan so that you know what to eat to make sure your diet is giving you all the nutrients you need.
Follow up care by the nutritional practitioner is also recommended to ensure the on-going diet is nutritionally adequate. How regularly this follow-up is needed will depend on the age of the patient and how many and what foods are being cut out of the diet. Such nutritional advice is especially important for infants and children.
Regardless of how hard a person with a food sensitivity tries to avoid eating the food which they react to, it is possible that this may happen. The actions that need to be taken after the food has been eaten are different according to what type of sensitivity you have. It is important that anyone with a food sensitivity themselves or anyone caring for someone with a food sensitivity knows what to do during/after a reaction, from understanding when to seek medical assistance (and how) to finding out what exactly caused the reaction (this is not always obvious). These details are given in the section entitled 'Life saving/food safety issues'.
Written by Kate Grimshaw PhD RD November 2013