So you think you have a food allergy?
A lot of people think they suffer from food allergies. They are cautious around the dinner table and quick to read the labels on their food packaging, but experts say true food allergies are less common than most people think.
Although up to 20-30% of people believe that they have a food allergy, it is estimated that only between 2% and 5% of the general population suffer from a definite food allergy according to an article in the South African Medical Journal.
Allergy or intolerance?
Associate Professor Jonathan Peter, head of the Allergology and Clinical Immunology division at UCT’s Department of Medicine and the Allergy clinic at the UCT Lung institute, says it’s important to distinguish between allergies and intolerances since the symptoms often overlap.
“Food allergies are caused by an abnormal immune response and cause a range of symptoms from mild e.g. hives or diarrhoea to life-threatening anaphylaxis. Food intolerances caused by other mechanisms such as enzyme problems e.g. lactose intolerance can also can similar symptoms, but reactions are normal limited to digestive problems,” Prof Peter explains.
“The most common food allergies in South Africa are to egg, peanuts, cow’s milk, tree nuts like hazelnuts and soya,” says Sasha Watkins, dietitian and director of EATFIT.
Symptoms of an allergic reaction
Watkins says there are two main types of food allergies, namely IgE-mediated (immediate type) and non-IgE mediated (delayed type). IgE stands for Immunoglobulin E and is a type of antibody produced by the immune system when your body reacts to an allergen.
Immediate reactions (IgE-mediated) occur within minutes to two hours of contact with the food, and symptoms include:
- Swelling of parts of the face
- A raised red itchy rash
- Itchy or red eyes
- An itchy mouth
- Nausea and vomiting
- Stomach pain
- A runny or blocked nose
- Shortness of breath or wheezing
Non IgE-mediated food allergies (or delayed reactions) occur hours to days after eating the offending food, and therefore it can be more difficult to recognise symptoms, which may include:
- Colicky pain
- Severe reflux
- Blood in the stool
Prof. Peter explains that an IgE-mediated allergic reaction in its worst form can lead to anaphylaxis. “Anaphylaxis can lead to cardiovascular symptoms, drop in blood pressure, coma and death ” he says.
What to do when you have allergy symptoms
According to Prof Peter there are three things you can do if you have symptoms of an allergic reaction:
- If you have anaphylaxis, you should make it a priority to see a specialist, identify the offending food and receive an anaphylaxis action plan.
- If you clearly have symptoms of an allergic reaction, but symptoms are less specific, get assessed by a doctor.
- If you are suspicious about your reaction to certain foods, keep a food diary in which you write down what you eat and how your body reacts to it. Use this to aid the doctor in identifying the offending food.