allergies

Food allergy and anaphylaxis

Written by Sonia Navidi - Dietician

Food allergies are common among Australian children and adults, affecting about 1 in 20 Australian children and 2 in 100 Australian adults. In most cases, food allergies will disappear with age, however they do persist into adulthood for some people. Allergies to peanuts, tree nuts, shellfish, fish, seeds and eggs are most likely to continue into adulthood.

Food allergies are caused when components of the body’s immune system, called mast cells, react to the presence of the food allergen in question. Food allergens are one of the proteins in a particular food that trigger an allergic response (for example, peanut protein). The mast cells’ response gives rise to the symptoms we associate with food allergies.

The most common foods to cause allergies are:

  • Cow's milk
  • Eggs
  • Peanuts
  • Tree nuts
  • Sesame seeds
  • Soy
  • Fish
  • Shellfish
  • Wheat

Symptoms of food allergy usually occur immediately after eating the food, and include:

  • Itching, burning and swelling around the mouth
  • Runny nose
  • Skin rash (eczema)
  • Hives
  • Diarrhoea and abdominal cramps
  • Breathing difficulties
  • Nausea and vomiting

In severe cases, people may have a life-threatening anaphylactic reaction to a food allergen. Anaphylaxis requires emergency treatment, and sufferers should carry an Epi-Pen (containing adrenaline) with them at all times.

Symptoms of anaphylaxis include:

  • Rapidly spreading hives
  • Swelling of the face, tongue and throat
  • Difficulty breathing
  • Wheezing
  • Vomiting
  • Loss of consciousness

What about intolerance?

Food allergies are caused by mast cells reacting to a protein in food. Food intolerances are not related to the immune system. They are caused when we have difficulty digesting a particular food, and although troublesome, are not life-threatening. For example, people with lactose intolerance lack the gut enzyme that helps breakdown lactose (the sugar in milk), which causes the typical symptoms such as wind, bloating and diarrhoea.

Diagnosing food allergies

Food allergies should only be diagnosed by a doctor or dietitian. Eliminating foods from your diet can lead to nutritional imbalances if not planned properly.

Your doctor will choose which diagnostic test to use based on the severity of your symptoms and other factors.

Tests include:

  • Skin-prick tests
  • Blood tests
  • Elimination diet
  • Oral food challenge

Alternative tests, such as cytotoxic food testing, Vega testing, kinesiology, allergy elimination techniques, iridology, pulse testing, Alcat testing, Rinkel's intradermal skin testing, reflexology, hair analysis and IgG food antibody testing, have not been shown to work. Further to this, they are not covered by Medicare. The Australasian Society of Clinical Immunology and Allergy (ASCIA)— the peak body representing allergy specialists in Australia and New Zealand— recommends against using these tests.

A note on eliminating wheat:

Some people find that they feel better when they eliminate wheat from their diet, without being diagnosed as having coeliac disease. If you think that you might have coeliac disease, it is important to continue eating wheat until you have been diagnosed by colonoscopy. If wheat is eliminated from the diet before having a colonoscopy, there is a chance that a person with coeliac disease may be misdiagnosed as not having the condition. It is important that coeliac disease is medically diagnosed (rather than self-diagnosis), as it requires strict lifetime exclusion of gluten. People with coeliac disease are also at higher risk of certain medical conditions, such as osteoporosis and type 1 diabetes, and will need to be monitored for these conditions developing.

Services at Community Pharmacy

Community Pharmacy conducts regular supermarket shopping tours with a dietitian. These tours are provided for free as a service for the community. For details of the next supermarket tour, go to ‘What’s On’. Community Pharmacy staff are also happy to assist you with vitamin and mineral supplements or Epi-Pens if required.

References:
The Australasian Society of Clinical Immunology and Allergy (ASCIA)
Better Health Channel
Coeliac Australia

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