Dr Sue Shepherd is an Advanced Accredited Practicing Dietician. To find an accredited dietitian visit www.shepherdworks.com.au
What is food allergy?
Food allergy occurs when your body has an abnormal immune response to particular food proteins. The body sees the food protein as harmful and it tries to defend itself, usually by making antibodies against the allergen. This occurs usually within minutes or up to 1-2 hours later and severity of symptoms can vary from mild, such as a rash around the mouth, to life threatening anaphylactic reactions. [*1,2] Food allergy and food intolerance can be confused as the symptoms are often similar.
Food intolerance is where your body reacts to factors found in food, such as natural food chemicals (salicylates, amines, monosodium glutamate (MSG), food additives or due to metabolic disorders like lactase deficiency (lactose intolerance) - where the body is not able to break down and digest lactose. It has not been shown to involve an immune response and symptoms usually take longer to present: from hours to days. [*1,2]
What are the symptoms of food allergy?
Symptoms can involve the skin, gut and airways and may include itchiness or swelling of the mouth or skin, vomiting, diarrhoea, stomach pain, eczema, throat tightness, difficulty breathing and anaphylaxis (a severe life-threatening reaction which can involve swelling and tightness in throat and trouble breathing). [*1,2,3]
What is the prevalence of food allergy?
It is estimated that 6% of young children have a food allergy and it affects between 1-2% of the general population. [*2] The most common foods contributing to food allergy are cow’s milk, hen’s egg, peanut, tree nut, fish and shellfish. Other allergens may include wheat, soy, sesame and crustaceans. [*4]
Food allergies are usually outgrown by age 5. For example, approximately 2.5% of infants have cow’s milk allergy in their first year of life, however, by 5 yrs of age most of them have outgrown this allergy. Peanuts, nuts and seafood allergies often persist into adulthood. [*5]
How is food allergy diagnosed?
There are a number of tests promoted to the general public that claim to diagnose food allergy. Many of these lack scientific evidence and may lead to unnecessary treatment. [*5]
To help in the diagnosis of food allergy, your health professional will take a detailed clinical history and record any suspected reactions to food(s) and if a specific food allergen can be identified, a skin prick test and/or radioallergosorbent test (RAST) may follow. These tests are carried out by a qualified medical practitioner. [*1,2]
A skin prick test involves a small prick to the skin, and a specified amount of the suspected food allergen extract is applied. Reactions are observed and interpreted.
It should be noted that you can have a positive skin prick test to a food allergen, without having an allergic reaction to that food. A qualified medical practitioner will diagnose a food allergy when a positive skin prick test and history of reactions suggest an allergy to the same food. [*2]
Some individuals may not produce the antibodies detected in skin prick and RAST testing and the only way they can be tested is through a food challenge.
Food challenges are considered the gold standard for diagnosis of food allergy however for individuals with life threatening reactions, the skin prick and RAST test are preferred. [*4]
How can food allergy be managed?
Once a food allergy has been diagnosed, the offending food needs to be removed from the diet. [*1] It is important to see a qualified and experienced dietitian (specialising in food allergies). The Dietitians Association of Australia (DAA) can help locate an Accredited Practising Dietitian. The dietitian will teach you about which foods you need to avoid and the possible substitutes for these whilst still following a nutritionally balanced diet.
I am dairy intolerant- what are my options?
One of the most common food allergies is cow’s milk and depending on the age this is diagnosed alternative food sources trialled may include soy infant formula (>6 months of age, soy may also be an allergen for some) or other low allergen formulas. Your health professional will provide you with expert advice on this depending on your diagnosis and special circumstances.
At 1-2yrs, if soymilk is tolerated, a calcium fortified soymilk should be chosen in order to help meet calcium requirements. At 2yrs of age (provided protein and other nutrients are adequate) ricemilk fortified with calcium (if cow’s milk and soymilk are not tolerated) may be a suitable alternative. [*6] Oatmilk fortified with calcium is another option, however please check with your health professional to ensure you meet your specific needs.
-A proper diagnosis of food allergy should be made by a qualified medical practitioner and once diagnosed the identified food allergen needs to be eliminated from the diet.
-A qualified Accredited Practising Dietitian will help provide you with food allergy specific advice and ensure your diet is nutritionally balanced.
-If an allergy to cow’s milk is present, an alternative may be soy, rice or oatmilk. However, this depends on whether any other food allergies are present, and also the age of diagnosis.
-Vitasoy products provide a range of lactose-free calcium-fortified options to help meet daily calcium needs easier.
1. Hodge L, Swain A, Faulkner-Hogg K. Food allergy and intolerance. Australian Family Physician 2009; Vol. 38, No. 9: 705-707
2. Hugh A.S. Food Allergy. Journal Allergy and Clinical Immunology 2003; Vol. 111; Supplement 2: S540-S547
3. Australasian Society of Clinical Immunology and Allergy (ASCIA). Diagnosis and management of food hypersensitivity in childhood. 2010. [cited sept 10: www.allergy.org.au/content/view/166/303/]
4. Schneider Chafen J.J, Newberry J.S, Riedl A.M, Bravata M.D, Maglione M, Suttorp J.M, Sundaram V, Paige M.N, Towfigh A, Hulley J.B, Shekelle G.P. Diagnosing and Managing Common Food Allergies: A Systematic Review. Journal of American Medical Association 2010; Vol 303, No. 18
5. Australasian Society of Clinical Immunology and Allergy (ASCIA) Position Statement: Unorthodox Techniques For The Diagnosis And Treatment Of Allergy, Asthma And Immune Disorders. 2007. [cited sept 2010: http://www.allergy.org.au/content/view/322/271/]
6. The Department of Allergy and Immunology, Royal Children’s Hospital. Cow’s Milk Allergy. 2007. [cited sept 2010: www.rch.org.au/emplibrary/allergy/Cows_Milk_Allergy.pdf]