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Understanding Food Allergies

Part 6 of the Dietetic Care article series focuses on Food Allergies.

What are food allergies?

Food allergies involve the immune system and occur in people who overreact to foods that are generally regarded as harmless. Allergic reactions to foods occur when the body’s immune system identifies a food protein or allergen as a ‘foreign body,’ and in response it activates defence systems to try to stop or eliminate the allergen, thus causing the symptoms of allergic reactions.

Food allergy can be mild or severe. It can be transient or last a lifetime.


People may also have adverse reactions to foods that are non-allergic, and I have previously provided an article on these reactions which are known as food intolerances. To gain a better understanding of the differences between food allergy and food intolerance please read the article entitled ‘Investigating Food Intolerance’.

How common is food allergy?

According to ASCIA, the Australian Society of Clinical Immunology & Allergy, the peak professional body of Allergists and Clinical Immunologists in Australia and New Zealand, food allergy occurs in around 1 in 20 children and 1 in 100 adults. The majority of food allergies in children are not severe and disappear over time, however, for some children food allergies can be life-threatening.

What foods commonly cause allergic reactions?

Children are commonly allergic to two or three foods, sometimes more. The most common ones are peanuts and tree nuts, cow’s milk and eggs. Less common triggers are seafood, sesame, wheat and soy. Wheat and soy allergies tend to be mild and transient. Fortunately most children grow out of egg, milk, wheat and soy allergies before they reach school age, however peanut, tree nuts (most commonly cashew nuts), seeds and seafood allergies may persist in adulthood.


The term tree nut is commonly used to mean nuts (Almond, Brazil, Cashew, Hazelnut, Macadamia , Pecan, Pine, Pistachio and Walnut.

How will my body react if I have a food allergy?

Allergic reactions can vary between individuals and can affect different systems of the body. In its mild and chronic form, eczema is the most common presenting symptom of food allergy. In its severe form reactions can occur immediately or within an hour or two of even the smallest amount of the offending allergen and result in itching, rash, hives, breathing difficulties, swelling of the mouth and throat or asthmatic attack and potentially circulatory collapse (anaphylaxis). When a severe reaction happens, the body will respond by producing its own adrenaline and recovery will occur, but under certain circumstances not enough adrenaline is produced, and the reaction may be fatal. Therefore, for those at risk of having anaphylaxis, management includes having an adrenaline auto-injector (EpiPen®) to have on hand at all times in the event of accidental exposure.


Food allergy symptoms can be immediate and may include:
  • Itchiness
  • Rash
  • Hives
  • Swelling
  • Runny nose
  • Breathing difficulties
  • Nausea
  • Stomach pains
  • Diarrhoea
  • Vomiting

People who have had an EpiPen® prescribed need to be aware of it’s correct usage, the expiry date and need to make sure that it is not exposed to high temperatures, so don’t leave it in the car! People needing an EpiPen® can join the EpiClub ( www.epiclub.com.au ) which sends you a reminder of when your EpiPen® expires and other management tips.

There is a parent support group called Anaphylaxis Australia http://www.allergyfacts.org.au/ which aims to develop anaphylaxis awareness through education, research & support.

Who is most likely to develop food allergies?

There is a genetic predisposition to becoming allergic. People with food allergy usually have a family history of allergic disorders such as asthma, eczema and hay fever. If a family has one child with food allergy, the brothers and sisters of that child have a greater risk of developing food allergy.

While food allergy tends to present in infants and very young children, asthma and hay fever tend to present as they get older.

How is food allergy identified?

A detailed clinical history will be taken by the doctor, and then either skin prick tests (SPT) or blood tests (radioallergosorbent test RAST) need to taken to confirm the presence of IgE antibodies in order for a diagnosis of allergy.

Food allergies should always be investigated by the appropriate medical professional i.e. GP/Immunologist and dietary adjustments should always be made under the supervision of an Accredited Practising Dietitian (APD) or Accredited Nutritionist (AN) who specialises in food allergy.

How do we treat food allergy?

After identifying the food trigger/s it is important to avoid the allergen/s to prevent further reactions. Levels of avoidance will vary depending on the severity of reaction, the age of the child, the type of food involved, and the family’s social situation. If total avoidance is advised this may include avoiding products that are labeled ‘may contain traces of the allergen.’ Sometimes reactions are so severe, for example in the case of peanut allergy, that airborne particles can be enough to trigger a reaction.

Unfortunately for the general public, advice from “experts” can be confusing, especially when it comes to whether or not we can prevent allergy, and how strictly they need to avoid the allergen if they are already allergic. At the moment more research is needed with respect to prevention of food allergy. Some “experts” advise that food avoidance will not prevent allergy, and others advise that avoidance of nuts and seafood by direct and indirect contact, and not binging on any foods (especially eggs and dairy), can lessen the likelihood of sensitisation.

Your GP/Immunologist will help you devise an Action Plan in the event of exposure to the allergen/s, especially where anaphylaxis is concerned. Recognizing the early symptoms of an allergic reaction and knowing what to do if it happens can help people with food allergy learn to live with their condition.

This article has briefly addressed some of the issues in the complex and controversial area of food allergy. If you suspect food allergy, consultation with your GP and or Immunologist is recommended.

If you or a family member has been diagnosed with food allergy and you wish to see an APD or AN in your area, you can go to the Dietitians Association of Australia website www.daa.asn.au. Click on ‘Find an APD’ and search for a dietitian or nutritionist specialising in food allergy by selecting ‘Allergy and Food Sensitivity’ under ‘Area of practice.’ Alternatively you can contact the allergy department at your local hospital or check the yellow pages under ‘D’ for Dietitian. For people living outside Australia contact the Dietitians Association in your country.

References:

  1. Calvi, K, Investigating Food Intolerance
  2. Australian Society of Clinical Immunology & Allergy, Food Allergy, ASCIA Education Resources, Patient Information; http://www.allergy.org.au/images/stories/aer/infobulletins/pdf/aer_food_allergy_april2009.pdf
  3. Dept. Allergy & Immunology, Children’s Hospital Westmead, Factsheet, Allergy – tree nuts, http://www.sch.edu.au/health/factsheets/joint/?tree_nut_allergy.htm
  4. Thomas, B, Manual of Dietetic Practice, Blackwell Publishing, 2002.
  5. Sampson HA. Food Allergy. Part 2: Diagnosis and Management. Journal Allergy Clinical Immunology 1999; 103 (6): 981-95.
  6. Wardlaw, G. M., Perspectives in Nutrition, McGraw-Hill, Boston, 1996
  7. Royal Prince Alfred Hospital, Friendly Food, Murdoch Books, 1997
  8. Tang MLK, Robinson M 2008, Allergy prevention. Current recommendations and new insights. Australian Family Physician 37(4): 204-208.
  9. Prescott SL, Smith P, Tang M, Palmer DJ, Sinn J, Huntley SJ, Cormack B, Heine RG, Gibson RA, Makrides M 2008, The importance of early complementary feeding in the development of oral tolerance: concerns and controversies. Pediatric Allergy Immunology 19: 375-380

Kyann Calvi is an Accredited Practising Dietitian (APD) who specialises in Food Allergy/Intolerance, Coeliac Disease and other gastrointestinal disorders such as Irritable Bowel Syndrome. For the past seven years she has helped people with food allergies/intolerance meet their nutrient needs through special diets. Kyann works in private practice locations in the Eastern suburbs of Melbourne.Contact Us

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