Many people say they are allergic to a food or something in its makeup, but often this could be more of an intolerance, or even just a dislike/distaste of a food.
So what is a true food allergy? (for info on food intolerance, see our article “Are you Intolerant”)
Allergies
- Food allergies are thought to affect around 5% of New Zealanders
- It’s hard to give an exact figure for the prevalence of food allergies because most of the data is self-reported and there may be a large number of people who haven’t been diagnosed officially [1].
What is a food allergy?
People develop a food allergy when their immune system reacts by creating antibodies against a harmless food protein.
What happens?
When the food is eaten, these antibodies (called IgE), recognise the protein and hook on to it. This results in the immune system going into action, culminating in an allergic reaction with varying symptoms [2].
Food allergies that are prompted by these IgE antibodies result in an immediate reaction (no more than two hours after eating) such as [2]:
- swelling
- an itchy rash
- diarrhoea
- vomiting
- anaphylaxis (difficulty breathing and collapse)
There are also food allergies that have delayed reactions – that is, they occur after two hours and up to a day later. These, however are not prompted by IgE antibodies. This type of allergy can result in gastrointestinal symptoms such as vomiting and/or skin reactions like atopic eczema [2].
Food allergy in adults
The types of foods we are allergic to can change, and children who have had allergic responses can grow out of them. In adults, the most common type of food allergy is known as pollen food syndrome or oral allergy syndrome and is often a reaction to raw fruits and vegetables [2]. It’s called pollen syndrome because it occurs in people who have antibodies that have been created against pollen, and these react with the proteins in the fruits and vegetables that are similar to pollen.
The most common foods involved include [2]:
- apples and stone fruit
- tree nuts (e.g. walnuts)
Other common foods that cause allergic reactions in the adult population include [2]:
- fish
- shellfish
- peanuts
- legumes
- seeds
- wheat
- soy
How do I know if I have a food allergy?
There are diagnostic tests that can identify food allergies caused by the IgE antibodies. These include both IgE blood tests and skin prick tests.
Because the delayed type of food allergy is not caused by the production of IgE antibodies, there are no diagnostic tests for this at present.
However, if you feel you have this type of allergy, excluding certain foods from the diet with the help of a health professional can help manage the situation.
What about other tests?
There are a growing number of tests used to test for allergies or intolerance. These include hair follicle tests, kinesiology, pulse tests and many more. Some people believe these tests are based on sound science, but clinical scientific research studies have not validated this to date [2].
If you suspect you have a food allergy, it’s best to work with a credible health professional. If part of the process is to eliminate these foods from your diet, care needs to be taken to ensure you’re getting all the right nutrients from your other foods.
Allergy NZ
Food (and non-food) allergies are potentially very serious. More detailed and comprehensive information can be found at www.allergy.org.nz
References
1. Crooks, C., Ameratunga, R., Simmons, G., Jorgensen, P., Wall, C., Brewerton, M., Sinclair, J., Steele, R. and Ameratunga, S., 2008. The changing epidemiology of food allergy–implications for New Zealand. The New Zealand Medical Journal (Online), 121(1271).
2. British Dietetic Association. Food Allergies and Intolerances. 2015 – [cited on 15 September 2017]. PEN Database
