Common food allergies
What is an allergy?
Allergies are a number of conditions caused by hypersensitivity of the immune system to something in the environment that usually causes little or no problem in most people. These diseases include hay fever, food allergies, atopic dermatitis, allergic asthma, and anaphylaxis. Symptoms may include red eyes, an itchy rash, runny nose, shortness of breath, or swelling. Food intolerances and food poisoning are separate conditions.
According to the Centers for Disease Control and Prevention (CDC), more than 50 million Americans have an allergy of some kind. Food allergies are estimated to affect 4 to 6 percent of children and 4 percent of adults.
What is food allergy?
When the body’s immune system reacts abnormally to something a person eats or drinks, it’s known as a food allergy.
- A food allergy reaction 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.
- According to Food Allergy Research and Education (FARE), it’s estimated that 15 million Americans have food allergies. Children are more likely to experience food allergies. Approximately 1 in every 13 children in the United States lives with food allergies.
- A food allergy may affect the skin, the gastrointestinal tract, or the respiratory or cardiovascular systems. Many types of foods can be allergens, but certain foods are much more likely than others to trigger an allergic reaction.
Symptoms of Food Allergies
Symptoms of food allergies may range from mild to severe and they may come on suddenly or develop over several hours.
Because a person’s immune system may react to a very small amount of the allergen, food allergies are particularly dangerous and potentially life threatening, especially if breathing is affected. Because of this, people with asthma are at an increased risk for a fatal allergic reaction to food. The most severe allergic reaction is anaphylaxis — a life-threatening whole-body allergic reaction that can impair your breathing, cause a dramatic drop in your blood pressure and affect your heart rate. Anaphylaxis can come on within minutes of exposure to the trigger food. It can be fatal and must be treated promptly with an injection of epinephrine (adrenaline).
Most food-related symptoms occur within two hours of ingestion; often they start within minutes. In some very rare cases, the reaction may be delayed by four to six hours or even longer. Delayed reactions are most typically seen in children who develop eczema as a symptom of food allergy and in people with a rare allergy to red meat caused by the bite of a lone star tick.
Mild symptoms related to a food allergy may include:
- stuffy or runny nose
- itchy, watery eyes
- stomach cramps
Severe symptoms of an allergic reaction to food are:
- difficulty breathing, including wheezing
- swelling of the lips, tongue or throat
- hives (an itchy, blotchy and raised rash)
- dizziness or faintness
- nausea or vomiting
- Shock or circulatory collapse
- Weak pulse
- Pale or blue coloring of skin
- Dizziness or feeling faint
- Anaphylaxis, a potentially life-threatening reaction that can impair breathing and send the body into shock; reactions may simultaneously affect different parts of the body (for example, a stomachache accompanied by a rash)
Another type of delayed food allergy reaction stems from food protein-induced enterocolitis syndrome (FPIES), a severe gastrointestinal reaction that generally occurs two to six hours after consuming milk, soy, certain grains and some other solid foods. It mostly occurs in young infants who are being exposed to these foods for the first time or who are being weaned. FPIES often involves repetitive vomiting and can lead to dehydration. In some instances, babies will develop bloody diarrhea. Because the symptoms resemble those of a viral illness or bacterial infection, diagnosis of FPIES may be delayed. FPIES is a medical emergency that should be treated with IV rehydration.
Food items that can trigger food allergies
According to FARE, eight foods are responsible for 90 percent of food allergies.
Like most food allergies, egg allergy is more common in childhood and about half the children who have it will grow out of it by the age of three. In a few cases, egg allergy can cause anaphylaxis. Egg allergy is mainly caused by three proteins in the egg white called ovomucoid, ovalbumin and conalbumin. Cooking can destroy some of these allergens, but not others. So some people might react to cooked eggs, as well as raw eggs. Occasionally someone might react to egg because they have an allergy to chicken, quail or turkey meat, or to bird feathers. This is called bird-egg syndrome.
Also avoid eggs in other forms, such as:
- Egg powder
- Dried eggs
- Egg solids
Some of the food items containing eggs are:
- Breaded and batter-fried foods
- Caesar salad dressing
- Cream pies, fillings, and puffs
- Crepes and waffles
- Custards, puddings, and ice cream
- Egg substitutes
- Coffee drinks like cappuccino (eggs are sometimes used to help create the foam)
- Lollipops and other candies
- Marshmallows and marzipan
- Meatloaf and meatballs
- Meringue and frostings
- Sauces, including Hollandaise and tartar sauce
- Simplesse (fat substitute)
- Some soups and consommés
- Wine (Egg whites may be used in the process of making wine.)
- Cow’s milk
A milk allergy is a reaction to whey or casein, the proteins found in cow’s milk. It’s not the same as lactose intolerance. Milk allergies have been studied more than any other food allergy. The bad news is that children with milk allergies are much more likely to develop allergic reactions to other foods including eggs, soy, and peanuts. Most children with milk allergies also develop one or more other atopic diseases such as asthma, allergic rhinitis, or eczema. Some of the milk products to avoid are:
- Butter and butter fat
- Cheese, including cottage cheese and cheese sauces
- Cream, including sour cream
- Milk, including buttermilk, powdered milk, and evaporated milk
- Ice cream
Children with peanut allergies rarely grow out of their sensitivity to peanuts, so a peanut allergy is usually a lifelong disorder. Because of this, peanut allergies are particularly serious. Accidental exposure can occur at any time during a person’s life. Though rare, a peanut allergy may result in anaphylaxis. This is a severe allergic reaction that can restrict breathing or cause cardiac arrest. Anaphylaxis requires immediate medical attention in the form of a shot of epinephrine (EpiPen). A patient should be watched for several hours after the shot to make sure symptoms don’t return.
Fish allergy can often cause severe reactions, including anaphylaxis. Adults are more likely to have an allergic reaction to fish and shellfish than children, which is probably because adults will have eaten these foods more often.
People who are allergic to one type of fish, such as cod, often react to other types of fish such as hake, haddock, mackerel and whiting as well. This is because the allergens in these fish are quite similar. Cooking doesn’t destroy fish allergens. In fact, some people with fish allergy can be allergic to cooked but not raw fish.
Allergy to shellfish is quite common, and a number of different types of shellfish can cause reactions in people who are sensitive, for example shrimps, prawns, lobster, crab, crayfish, oysters, scallops, mussels and clams. People who are allergic to one type of shellfish often find that they react to other types. Shellfish allergy can often cause severe reactions, and some people can react to the vapours from cooking shellfish.
- Tree nuts (such as cashews or walnuts)
Peanuts and tree nuts aren’t the same. But if you’re allergic to one, you may also need to avoid the other. Ask your doctor to be sure.
Tree nuts include:
- Brazil nuts
- Hickory nuts
- Macadamia nuts
- Pine nuts
Food Items that may contain tree nuts include:
- Baked goods. Cookies, candy, pastries, pie crusts, and others
- Chocolate candy especially; also nougat and marzipan
- Other sweets. Ice cream, frozen desserts, puddings, and hot chocolate
- Cereals and granola
- Trail mix
- Chili and soups. Peanuts or peanut butter are sometimes used as thickeners.
- Grain breads
- High-energy bars
- International foods. Nuts are common ingredients in African and Asian cooking (especially Thai and Indian); also in Mexican and Mediterranean foods.
- This Italian ham may include pistachios.
- Veggie burgers
- These may include barbeque sauce, hot sauce, pesto, gravy, mole sauce, glazes, or marinades.
- Salads and salad dressing
Wheat allergy is common, particularly among babies. One of the main allergens in wheat is a protein called gliadin, which is found in gluten. Because of this, people with a wheat allergy are sometimes recommended to eat a gluten-free diet.
Foods with wheat protein include:
- Bread crumbs
- Durum, durum flour, and durum wheat
- Farro (also known as emmer)
- Sprouted wheat
- Wheat (bran, germ, gluten, grass, malt, starch)
- Wheat berries
- Wheat flour (all types, including all-purpose, cake, enriched, graham, high protein or high gluten, and pastry)
Soya allergy is a common childhood allergy. Most people grow out of it by the age of two, but occasionally adults are allergic to soya. The symptoms of soya allergy are similar to milk allergy, and they include rashes, diarrhoea, vomiting, stomach cramps and breathing difficulties. Some people with soya allergy might also react to milk. Very rarely, soya can cause anaphylaxis. Soya is used as an ingredient in about two-thirds of all manufactured food products, including bakery goods, sweets, drinks, breakfast cereals, ice cream, margarine, pasta, processed meats and seasoned foods. Soya can be described in a number of different ways on food labels, for example as hydrolysed vegetable protein, vegetable oil and lecithin. Soya flour is used to increase the shelf life of many products and to improve the colour of pastry crusts. Textured soya protein, which is sometimes called textured vegetable protein, is made from compressed soya flour. It’s used as a meat substitute and to improve the consistency of meat products. Refined soya oil (the main component of vegetable oil) should be safe for people with soya allergy, because the proteins that cause allergic reactions are removed during the refining process.
Children who are allergic to cows’ milk are sometimes given soya-based formulas as a substitute. But people with a cows’ milk allergy can sometimes be allergic to soya too. So soya-based formulas might not be suitable for children with cows’ milk allergy. Highly hydrolysed milk or casein formulas are often recommended for these children. Ask your GP for advice. Sometimes people with an allergy to soya will also react to foods such as peanuts, green peas, chickpeas, rye and barley flour.
Soy foods that you can avoid include:
- Soy sauce and shoyu sauce
- Soy-based fiber, flour, grits, nuts, or sprouts
- Soy-based milk, yogurt, ice cream, or cheese
- Soy protein
- Textured vegetable protein (TVP)
Other food items that can trigger food allergies
Some of the other food items can also trigger food allergies. These include:
- Meat — beef, chicken, mutton, and pork
- Seeds, often sesame, sunflower, and poppy
- Spices, such as caraway, coriander, garlic, and mustard
How food allergies are diagnosed?
A food allergy will usually cause some sort of reaction every time the trigger food is eaten. Symptoms can vary from person to person, and you may not always experience the same symptoms during every reaction. Allergic reactions to food can affect the skin, respiratory tract, gastrointestinal tract and cardiovascular system. It is impossible to predict how severe the next reaction might be, and all patients with food allergies should be carefully counseled about the risk of anaphylaxis, a potentially fatal reaction that is treated with epinephrine (adrenaline). While food allergies may develop at any age, most appear in early childhood.
Food allergies are usually diagnosed depending on the severity of symptoms. If a patient’s symptoms are mild, a doctor may recommend keeping a food diary to record all of the foods you eat or drink to pinpoint the culprit. Another way to diagnose a mild food allergy is to remove certain foods from the diet and then slowly reintroduce them to find out if symptoms return. In the case of more severe allergies, skin or blood tests can identify egg, milk, nut, and shellfish allergies.
Treatment of food allergies
As with other types of allergies, avoidance is most often the best medicine. Anyone with a food allergy should be careful when purchasing food at a supermarket or restaurant to make sure there are no traces of the allergen in a food or meal. Milder symptoms may not require any treatment at all, or a simple over-the-counter antihistamine may resolve the symptoms. For more serious allergic reactions, a doctor may prescribe steroid medications. Steroids may have serious side effects and shouldn’t be used for more than a few days at a time.