Food allergies - the facts
Australia has one of the highest food allergy prevalence rates in the world. Liz Nowosad explores the facts of food allergy and intolerance.
It’s estimated that one in three Australians will experience an allergy at some point in their lives, be it very mild or potentially life threatening. In a study conducted by The Australasian Society of Clinical Immunology and Allergy, 4.1 million Australians –19.6 per cent of the population – have at least one allergic disease.
Suffer from food allergies? It’s estimated that one in three Australians will experience an allergy at some point in their lives, be it very mild or potentially life threatening. In a study conducted by The Australasian Society of Clinical Immunology and Allergy, 4.1 million Australians –19.6 per cent of the population – have at least one allergic disease.
Allergies occur when the immune system overreacts to substances in the environment. These allergens are commonly found in house dust mites, pets, pollen, foods, drugs, insect stings, latex and moulds.
FOOD ALLERGY AND INTOLERANCE
Food allergy occurs in around 1 in 20 children and approximately 1 in 100 adults. That’s approximately 65,000 Australian children and 96,000 adults. Food intolerance is even more common with surveys indicating that up to 25 per cent of the population believe they have some sort of food intolerance. Currently, there is no cure for food allergy and the only successful way to manage an allergy or intolerance is to avoid the foods containing that allergen or food component.
WHAT IS A FOOD ALLERGY?
A food allergy is an immune system over-response to a food protein, known as an allergic reaction. Our immune system mistakenly identifies an allergen as an invader and begins to create antibodies against it. These antibodies (called IgE) attach themselves to mast cells found under the surface of our skin, in our nose, eyes, lungs and gastrointestinal tract. The IgE antibodies grab the allergen and alert the mast cells to release powerful chemicals, including histamine.
The reaction can happen minutes or hours after contact and may lead to many different symptoms, including hives, itching, swelling, vomiting, diarrhea and nausea. In some cases it can cause potentially life-threatening symptoms, namely anaphylaxis, where the respiratory and/or cardiovascular systems as well as the skin and/or gastrointestinal tract are affected. The most common food allergens, responsible for up to 90 per cent of all allergic reactions, are the proteins found in cow’s milk, eggs, peanuts, gluten, soy, fish, shellfish and tree nuts.
WHAT IS A FOOD INTOLERANCE?
For the majority of us, symptoms such as bloating after eating certain foods are most likely caused by food intolerance rather than allergy. Food intolerance is an adverse reaction to a food that doesn’t involve the immune system. Symptoms can be quite vague and may include a combination of gastrointestinal problems such as bloating and flatulence, diarrhea, nausea and indigestion. Intolerance can also aggravate eczema or asthma.
These symptoms can be immediate or delayed for up to 20 hours after a food is eaten. Although some tests used to diagnose food intolerances are more respected than others, none are 100 per cent reliable. For this reason, most specialists recommend an elimination diet, where you completely remove all the foods from your diet that you suspect of causing intolerance for one-to-three weeks. Then, reintroduce a small amount of one of the suspects and if symptoms reappear, the intolerance is confirmed. If you have no reaction, continue adding the suspect foods one at a time until you find out which one is causing problems.
“This test can also be performed to diagnose a food allergy,” say Allergy New Zealand. “It’s important this test is undertaken under the supervision of an experienced doctor, allergy specialist or registered dietitian to ensure that proper nutrition is maintained. If there is a risk of a severe reaction, foods should never be reintroduced without first consulting a health professional, especially in children. Undertaking an elimination diet to get to the bottom of what’s causing food intolerance can be a slow frustrating process but try and stick with it. Unfortunately, there are no ‘quick fixes’ where diagnosing intolerance is concerned; be suspicious of anyone offering an easy answer.”
THE USUAL SUSPECTS
Almost any food can cause intolerance, but like food allergy, some foods are more likely to than others. Lactose, found in cow’s milk and dairy products, is the most common intolerance. If you are bloating or have diarrhea after eating/drinking dairy, try switching to alternatives such as soya, oat or rice milk and see if you notice an improvement.
A specific type of allergy can develop to the protein in wheat and other grains such as rye, barley and oats called gluten, though more people react to wheat than any other. This condition is called coeliac disease. The true prevalence of coeliacs in Australia is not known, but it is possibly as high as 1 in 70 people. Coeliac disease is predominantly seen in Caucasians and it seems it may be more common in people who have a Celtic background.
Intolerance to yeast, found in bread as bakers yeast and beer or lager as brewer’s yeast, is also common. You may experience bloating after eating bread but not pasta, in which case it is most likely the yeast you are reacting to. If beer leaves you bloated and windy, try swapping for champagne or spirits.
Other common causes of food intolerance include salicylates – natural preservatives found in a wide variety of fruits, vegetables, nuts and spices; amines – produced during fermentation, aging and ripening; and glutamate – an amino acid found naturally in all protein foods.
If you suffer symptoms of allergy or intolerance, make an appointment to see an allergy specialist. After a consultation they will be able to identify the most likely cause. They know to listen for certain clues, such as the foods you crave or are addicted to, because often the foods we yearn for the most are the ones that cause us the problem. While the results of allergy testing are a guide to whether the person is allergic, they do not provide a reliable guide to whether the reaction will be mild or severe. Information on allergy testing is available on the ASCIA website. Tests used by doctors and allergy specialists include skin prick testing, blood tests for allergen specific IgE (RAST), total IgE testing, eosinophil counts, patch testing and challenge testing.
BEWARE UNORTHODOX ALLERGY TESTING
Do your research before handing over your money to get a diagnosis. According to The Australasian Society of Clinical Immunology and Allergy (ASCIA), there are several methods of unorthodox, so-called tests for food allergy. Examples include 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. “These have no scientific basis, are unreliable and have no useful role in the assessment of allergy. These techniques have not been shown to be reliable or reproducible when subjected to formal study.” ASCIA advises against the use of these tests for diagnosis or to guide medical treatment.