food allergy

The term ‘allergy’ is often misused to describe annoying symptoms such as bloating after drinking a cup of milk. As a result, many people think they have a food allergy when it is, in fact, an intolerance. There is also a widespread belief that food allergies are trivial when, in fact, they have an enormous impact on your everyday life.

A food allergy is an immune system over-response to a food protein and the body triggers an allergic reaction. Symptoms can include hives, itching, swelling, vomiting, diarrhoea and nausea. In some cases, it can cause potentially life-threatening symptoms, called anaphylaxis, either by breathing difficulties and/or a sudden drop in blood pressure.

Sometimes food allergy may be less obvious and can be characterised by infantile colic, reflux of stomach contents, eczema, chronic diarrhoea, and failure to thrive. Recent studies have found that up to 40-50 per cent of eczema cases in young children are triggered by food allergy.

Between 6 and 8 per cent of children have a food allergy, and between 2 and 4 per cent of adults. In children, the most common allergies are to cow’s milk and egg, followed by soy, peanuts, tree nuts and wheat. The majority of children will lose their allergies by age three to five years. But allergies to peanuts, tree nuts, fish and shell fish are generally prolonged, which is why these four allergies are the most common amongst adolescents and adults.

Several theories have attempted to explain the rise in food allergies and one leading theory is the ‘hygiene hypothesis’. This theory suggests that exposure to certain germs and infections early in life are important in training the immune system to recognise foreign threats to our body. Our tendency to lead a lifestyle of cleanliness and hygiene means our children don’t get exposed to these ‘good bugs’ and their immune systems have become over-reactive.

Another explanation for the rise in food allergy is the introduction of foods too early in an infant’s development before the immune system is mature enough to handle them. This could occur through the allergenic food passing through breast milk or an unintended exposure in life through highly processed foods typical of the Western diet with some foods containing hidden sources of the allergy-causing food.

However, this particular theory is now being challenged and the Australasian Society of Clinical Immunology and Allergy says that there is no evidence that delaying the introduction of food, included "allergenic" food, prevents food allergy. The peak professional body of immunologists and allergists in Australia and New Zealand introduced new infant feeding guidelines in December 2008.

Treatment and prevention

Although there is no cure yet for food allergy, research in the last decade has increased exponentially and researchers are getting much closer to developing a vaccine. They are also looking at changing the way the immune system responds to allergens through desensitisation - this works much the same way as allergy shots work for hay fever.

But until this comes into fruition, avoiding the allergenic food is the only treatment. Most importantly is that if you suspect you — or your child — have a food allergy, you should see an experienced GP, paediatrician or allergy specialist.

Once a diagnosis has been made, either through a skin prick test or a blood test in conjunction with a detailed history, you will have to be taught how to read food labels to appropriately avoid the food you are allergic to, how to recognise early symptoms of a reaction and how to treat it. This is where Allergy New Zealand can help.

There is no proven way to prevent allergies but there are a number of steps that may reduce the risk including exclusive breastfeeding for the first six months, delaying the introduction of solids to age six months, and avoiding exposing your baby to cigarette smoke.

Food labels

Going to the supermarket takes on a whole new meaning when you are avoiding common foods. You need to learn to read food labels and prepare more foods from scratch that you may have before. And every time you buy, you will need to read every label every time – manufacturers change their ingredients or processing aids from time to time!

Since December 2002, New Zealand’s food labelling laws require that the most common allergenic foods be stated on food labels. This includes milk, egg, soy, peanut, tree nut, sesame, fish, shellfish and gluten-containing cereals, including wheat.

While it is not mandatory for manufacturers to include precautionary statements such as ‘may contain traces of peanuts’, these are usually only used if the manufacturer feels there is a significant risk of cross contamination; for example, if biscuits containing peanuts are produced on the same line as another biscuit.

Read more on shopping for food allergies here.

			Updated October 2009