Food Allergy: Understanding Reactions, Intolerances, and Management
By Kepha Nyanumba
Food allergy is a serious and potentially life-threatening condition, which appears to be increasing in prevalence. Experts estimate that up to 8 percent of children suffer from food allergy compared to 1-2 percent adults who are affected. A food allergy is defined as, “an adverse reaction that occurs when your immune system overreacts to a food or a substance in a food, identifying it as a danger and triggering a protective response.”
While any food could possibly cause an allergy, certain foods are much more likely to do so. The foods that most commonly cause allergic reactions include: peanuts, eggs, soy, milk, wheat, etc. Most allergic reactions occur within 30 minutes of consuming these foods, but it can occur as long as 4 to 6 hours after ingestion.
Food Allergy vs. Intolerance
The difference between food allergies and food intolerances is often confusing. With these medical conditions having potential overlapping symptoms, it is easy to see why the line separating the two is so often blurred.
Food Allergy
Food allergy, also called hypersensitivity, involves an inappropriate immune reaction to a seemingly harmless, non-pathogenic substance. The body reacts to the substance as if it were fighting a disease-producing microorganism.
On first exposure to the offending food, the body’s immune system produces antibodies which are specific to that allergen. With any subsequent exposure, the allergen binds to the antibodies, which triggers the immune system to initiate a more rapid and aggressive response. This intense reaction can produce oral inflammation, cramps, nausea, diarrhea, gas, hives, and sometimes can produce respiratory distress.
Symptoms can appear immediately after eating or could take several hours to appear and can range from mild to severe. The most severe reaction, anaphylactic shock, affects the whole body, with symptoms usually presenting within one hour following contact. Symptoms include wheezing, difficulty breathing, swelling of the throat and tongue, vomiting, and fainting. Anaphylaxis can be deadly and requires immediate medical attention. People with known allergies should carry a medicine that counteracts the reaction, in case of exposure to the food.
Food Intolerance
In contrast to food allergy, food intolerance does not involve the body’s immune system. Intolerance is an adverse reaction to a food, likely to originate in the gastrointestinal system, usually caused by a limited ability or an inability to digest or absorb certain foods or their components. Food intolerance symptoms usually begin about half an hour after eating or drinking the food in question, but in some circumstances may not appear for up to 48 hours. Symptoms include nausea, bloating, abdominal pain, and diarrhea.
Examples of food intolerance include:
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Lactose Intolerance: Up to 70% of the world’s population is unable to consume milk or dairy products without getting an upset stomach. Typically, the human body can produce the enzyme lactase, which helps digest the sugar found in milk (lactose); however, people who are lactose intolerant do not produce a sufficient quantity of lactase and, therefore, digestion of milk-containing foods is not adequate. Undigested lactose lingers in the intestine and ferments, causing abdominal pain, bloating, diarrhea, and flatulence.
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Gluten Intolerance: Gluten is a protein in cereals such as wheat, barley, and rye. A person with gluten intolerance or sensitivity may experience pain and bloating after eating foods that contain gluten. Gluten intolerance leads to discomfort, but it is unlikely to cause severe symptoms that require emergency care.
The Tests Commonly Used to Determine Food Allergies
Many times, the diagnosis of food allergy can be made by dietary history. For example, if a person has hives or swelling of the face after eating something with peanuts, they are likely allergic to peanuts. But because symptoms can be so varied, the diagnosis is sometimes harder to make. A detailed documentation of food intake, symptoms, and information about food allergies in the family can be helpful. But you may need to do testing to be sure of the offending foods. There are three commonly used tests:
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Skin Tests: The allergy skin-prick test is the most common screening test because it is inexpensive, easy to do, and generally reliable. It involves pricking the skin with a solution of the suspected food. A positive test will produce a small hive-like reaction. The downside of this test is that it is uncomfortable, and for people with eczema or other skin conditions, the results may be difficult to interpret. In people with severe allergies, even the small amount of the food injected into the skin can cause significant reactions.
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RAST Blood Tests: Radioallergosorbent (RAST) laboratory tests measure the number of food-specific antibodies in the blood. The antibodies are made by the body in response to allergens. Once you have developed these antibodies, they are constantly circulating in your blood. Therefore, this blood test can be done at any time. The greater the number of antibodies, the higher the probability the person has an allergy to that particular food. RAST tests have the advantage of being less uncomfortable and can be done without stopping antihistamines.
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Elimination Diet: Another way to diagnose food allergies is through an elimination diet. An elimination diet is a meal plan that avoids or removes certain foods or ingredients to find out the foods that cause allergic reactions. The most common reason for an elimination diet is because you think certain foods may be the reason for your allergy symptoms. There are two parts to an elimination diet:
- Elimination phase: The first step is to stop eating the suspicious foods. You’ll need to read food labels carefully and ask how foods are prepared. Keep a food diary and write down everything you eat, and note how you feel after you eat them.
- Reintroduction (challenge) phase: After eliminating possible food allergy triggers, you should slowly add back suspicious foods, one at a time under medical supervision. This process helps you know exactly which foods cause allergic reactions. It’s helpful to keep a food diary of everything consumed and the amounts. This approach is appropriate if the reaction is mild and doesn’t cause any trouble with breathing.
Management of Allergies
Nutrition intervention in the management of food allergy aims to prevent acute and chronic food allergic reactions through allergen elimination while ensuring optimal nutrition within the context of the allergen-restricted diet. This requires careful planning and it’s easier when you do your own grocery shopping and prepare your own foods.
Check food packages, carefully reading the ingredients to ensure that they don’t contain anything that triggers allergic reactions. It’s also advisable to find out if the foods you are allergic to are known by any other names in the market.
Since you will be avoiding certain foods, it means that you will lack the nutrients that they provide. Always consult a nutritionist to get alternative sources of these nutrients that will be safe for you.
Kepha Nyanumba is a Consultant Nutritionist at Crystal Health Consultants Limited. You can engage him on this or related matters via mail: KNyanumba@chc.co.ke, or follow him on twitter at: knyanumba.