What are the most common food allergies in adults, and how can you find out if you're at risk? Andrew Cate investigates.
What is a food allergy?
A food allergy occurs when your body has an adverse reaction to the proteins in food, triggering an immune response. That food may be harmless to most people, but in people who experience an allergic reaction, the immune system will treat the food as toxic. The body produces antibodies to fight off the allergy causing component of the food, resulting in inflammation.
This is different to a food intolerance, where the body does not produce any or enough of the enzymes needed to break down a food. While the symptoms of food intolerance are usually less severe, they can be similar to those of a food allergy.
What are the symptoms of a food allergy?
The symptoms of a food allergy usually impact upon three main areas of the body, namely the skin, the digestive tract and the respiratory system. Symptoms can be both minor and severe, and usually appear within a few minutes to two hours after the culprit food is consumed.
The most common allergic reactions are:
hives, flushed skin or rash, tingling or itchy sensation in the mouth, itchy eyes and coughing.
vomiting and/or diarrhoea, abdominal cramps, swelling of the throat, tongue and vocal cords, difficulty breathing, inability to speak or swallow properly, rapid heartbeat, drop in blood pressure, anaphylaxis, and loss of consciousness.
What foods are most likely to cause an allergic reaction?
Almost any food can trigger an allergic reaction, although there are some foods that are most likely, including:
- tree nuts (eg, almonds, walnuts, pecans)
- shellfish (eg, crab, lobster, prawns)
- wheat (gluten)
Could you have a food allergy and not know it?
People can be unaware that they have a food allergy because their reaction is mild or delayed, or because they associate their allergic reaction with another cause. Symptoms can differ greatly among individuals and can also vary depending on the quantity of the allergic food eaten.
How do you diagnose a food allergy?
If you suspect you may have a food allergy, look for any patterns in terms of the onset, location, severity and duration of symptoms. You can also eliminate foods over a few days that contain suspect ingredients, and monitor if your symptoms disappear. You can also re-introduce a small amount of the suspect food to see if any symptoms return. Take note of the details and discuss it with your doctor who can rule out other causes, and refer you to an allergy specialist or immunologist if required.
Living with a food allergy
The best way to deal with a diagnosed food allergy is to avoid the triggers, and if exposed, relieve the symptoms. To help minimise your exposure, do some research to find out what foods your allergen is hidden in, what restaurants can cater for you and what to look out for on food labels.
It's also wise to have an action plan to help manage your allergy, making sure the correct medication is available, and that family, friends and co-workers know what to do in case of an emergency.
Be wary of unproven allergy tests
When a food allergy is suspected, doctors use a variety of clinical tests for an accurate diagnosis, including skin and blood tests, or a supervised elimination diet.
Several other unorthodox methods of testing for food allergies also exist. These methods include cytotoxic food testing, Vega testing, kinesiology, iridology, pulse testing, Alcat testing, Rinkel's intradermal skin testing and IgG food antibody testing.
Though these may be helpful, be aware that their efficacy is controversial. According to the Australasian Society of Clinical Immunology and Allergy, these testing methods have "no scientific basis, are unreliable and have no useful role in the assessment of allergy".