Wheat allergy

Symptoms

If you or your child has wheat allergy, you or your child will likely experience symptoms within a few minutes to a few hours after eating something containing wheat. Wheat allergy symptoms include:

• Swelling, itching or irritation of the mouth or throat
• Hives, itchy rash or swelling of the skin
• Nasal congestion
• Itchy, watery eyes
• Difficulty breathing
• Cramps, nausea or vomiting
• Diarrhoea
• Anaphylaxis

Anaphylaxis

For some people wheat allergy may cause a life-threatening reaction called anaphylaxis. In addition to other signs and symptoms of wheat allergy, anaphylaxis may cause:

• Swelling or tightness of the throat
• Chest pain or tightness
• Severe difficulty breathing
• Trouble swallowing
• Pale, blue skin colour
• Dizziness or fainting
• Weak pulse

Age of onset

A wheat allergy may not be a life-long disorder. Whether or not you outgrow it may depend, in part, on when the allergy first appears.

• Young children. Wheat allergy in children usually develops during infancy or early toddler years. Most children with wheat allergy have other food allergies. Children usually outgrow wheat allergy between ages 3 and 5.
• Adolescents and adults. Wheat allergy isn't as common in adolescents and adults.

Causes

An allergic reaction is somewhat like a case of mistaken identity by your body's immune system. Normally, your immune system generates antibodies to protect your body against bacteria, viruses or toxic substances.

If you have wheat allergy, your body generates an allergy-causing antibody to a protein found in wheat. In other words, your immune system mistakenly identified this protein as something that could harm you. Once your body has developed an allergy-causing antibody to a particular agent (allergen) — in this case, a wheat protein — your immune system will be sensitive to it. When you eat wheat, your immune system mounts an attack.

There are four different classes of proteins in wheat that can cause allergies: albumin, globulin, gliadin and gluten. Any of them can cause an allergic reaction.

Sources of wheat proteins

Some sources of wheat proteins are obvious, such as bread, but all wheat proteins — and gluten in particular — may be used in a number of prepared foods. Foods that may include wheat proteins include:

• Breads
• Cakes and muffins
• Breakfast cereals
• Pasta
• Couscous
• Crackers
• Beer
• Hydrolyzed vegetable protein
• Soy sauce
• Condiments, such as ketchup
• Meat, crab or shrimp substitutes
• Coffee substitutes
• Meat products, such as hotdogs
• Dairy products, such as ice cream
• Natural flavorings
• Gelatinized starch
• Modified food starch
• Vegetable gum

If you have a wheat allergy, you may also be allergic to other grains with similar proteins. These related grains include:

• Barley
• Oat
• Rye

Wheat-dependent, exercise-induced anaphylaxis

Some people with a wheat allergy develop symptoms only if they exercise within a few hours after eating wheat. Changes in your body related to exercise either trigger an allergic reaction or worsen an immune system response to a wheat protein. This condition usually results in life-threatening anaphylaxis.

If you have exercise-related allergy to wheat, you may also experience an anaphylactic reaction when you consume wheat and take aspirin or certain nonsteroidal anti-inflammatory drugs (NSAIDs) within a few hours.

The connection between these seemingly unrelated factors may be that exercise and aspirin use similar biological mechanisms to promote an allergic reaction to wheat.

Baker's asthma

Baker's asthma is an allergic reaction to wheat flour and other types of flour. As the name of the disorder suggests, it's a particular problem for bakers or anyone who works with uncooked wheat flours. The allergic reaction is triggered by inhaling flour rather than eating it. Baker's asthma primarily results in problems breathing.

The allergy-causing substance in baker's asthma may be one of the four wheat proteins or another substance, such as a fungus.

Celiac disease

Celiac disease, or gluten-sensitive enteropathy, is considered a food sensitivity rather than a food allergy. Celiac disease is an immune system reaction to gluten that causes inflammation in the small intestines. This condition can result in poor absorption of essential nutrients from your food. A person may have both wheat allergy and celiac disease. 

Risk factors

Certain factors may put you at greater risk of developing a wheat allergy:

• Family history. You're at increased risk of allergy to wheat or other foods if your parents have any food allergies or other allergies such as hay fever.
• Age. Wheat allergy is most common in babies and toddlers, who have immature immune and digestive systems. Most children outgrow wheat allergy.

Diagnosis

Your doctor will likely use a combination of tests, including a thorough physical exam, to make a diagnosis. Tests or diagnostic tools may include:

• Food diary. A detailed record of what and when you eat, as well as when you experience symptoms, may help your doctor identify the cause of a food allergy.
• Elimination diet. Your doctor may recommend a diet with certain foods removed, particularly those foods that are common allergens. Under your doctor's direction, you will gradually add foods back into your diet and note when symptoms return.
• Food challenge testing. With this test, you eat capsules containing the food suspected of being the allergy-causing agent. Under careful supervision for a few hours or days, usually at a hospital, you begin with a small amount of the food and gradually increase the amount you consume. During the test, you're monitored for any allergy symptoms.
• Skin test. In this test, tiny drops of purified allergen extracts — including extracts for wheat proteins — are pricked onto your skin's surface. This is usually carried out on the forearm, but it may be done on the upper back. The drops are left on your skin for 15 minutes before your doctor or nurse observes your skin for signs of allergic reactions. If you're allergic to wheat, you'll develop a red, itchy bump where the wheat protein extract was pricked onto your skin. The most common side effect of these skin tests is itching and redness. This usually goes away within 30 minutes.
• Blood test. In some cases a skin test can't be performed because of the presence of a skin condition or because of interactions with certain medications. As an alternative, your doctor may order a blood test that screens for specific allergy-causing antibodies to various common allergens, including wheat proteins.

References

http://www.mayoclinic.org/diseases-conditions/wheat-allergy/basics/definition/con-20031834

http://www.webmd.com/allergies/guide/wheat-allergy

http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(79)91735-5/abstract

http://acaai.org/allergies/types/food-allergies/types-food-allergy/wheat-gluten-allergy