Tales of life-threatening nut allergies and increasing celiac disease are rife, but are food allergies on the rise? Jane Dostine separates fact from fiction.
Myth: Food allergies are very common
Twenty-five per cent of Australians claim they have a food allergy. However, the reality is that only 1-2% of adults are affected. If you have a reaction to something in your diet, don't jump to conclusions, seek professional advice. Food allergies are mostly a problem for babies and young children, affecting between 6-8% of them. Reactions are rarely life-threatening and are most likely to cause eczema (an itchy skin rash) or hives, which often occurs on the face or around the mouth.
Myth: An allergy is an extreme form of intolerance
Allergies are caused by the stimulation of the immune system to form antibodies in our blood stream and body tissues. They can be detected by skin-prick testing and blood tests. When you have symptoms that don't involve the immune system, experts call it intolerance. The underlying physiological cause is often unclear and can't be detected by allergy testing. Understanding the difference is important because allergies are about avoidance but intolerances are dose related.
Myth: Allergies are not increasing – there is just greater awareness
The Australasian Society of Clinical Immunology and Allergy (ASCIA) reports that allergic disease has almost doubled over the past 25 years. Dust mites, pollen, foods, animal hair, insect stings and mould are just some of the things which cause allergic reactions. In young children, food is the most common cause of severe allergy. There has been a dramatic increase in peanut allergies with one in 50 Australian children suffering – doctors and researchers aren't sure why.
Myth: If you're allergic to one food you'll be allergic to many
Children are usually allergic to two, three or more foods. Most recover by the age of four, so if you're an adult reacting to a lot of different foods, it's probably intolerance rather than an allergy.
Myth: Milk allergy is quite common in adults
Most children outgrow a milk allergy and can safely reintroduce dairy products into their diet. However, some children and adults have symptoms that can be attributed to milk intolerance, which is often caused by lactose, a sugar found in all animal milks, including breast milk. Our gut is lined with lactase, an enzyme that digests lactose. If there's not enough lactase, the gut can't digest milk and it passes through causing discomfort and diarrhoea. Occasionally, lactose intolerance causes muscle pain, headaches, fatigue and constipation. A bout of gastroenteritis can temporarily strip your gut of lactase, causing people to be lactose intolerant for several weeks afterwards.
Myth: Nuts are the cause of most food allergies
Although peanut allergy is becoming increasingly common, children can be allergic to a variety of foods, including eggs, milk, soy, wheat, seafood, tree nuts and sesame. Egg is the most common food allergy, but nuts are associated with more severe reactions. Most children outgrow food allergies by the age of four, but nut and seafood allergies tend to persist into adulthood.
Myth: Wheat allergies are on the rise
Wheat allergies are relatively uncommon, rarely occur beyond infancy and reactions are usually mild. Most people who avoid wheat and other gluten-containing grains (rye, barley and, to a lesser extent, oats) have an intolerance rather than an allergy. Some have a condition known as coeliac disease, where gluten damages the lining of the gut. Coeliac disease runs in families and affects about one in 100 Australians (more are possibly undiagnosed). Blood tests are available, but a definite diagnosis requires a small bowel biopsy. Treating coeliac disease involves adhering to a life-long gluten-free diet to protect the gut and prevent bowel cancer.
Myth: Allergies can be cured
Although immunotherapy (desensitisation) by injection or oral drops is available for hay fever and asthma where they cause severe symptoms, this isn't an option for food allergies. A food allergy is managed by complete avoidance of that food. Birth to two years is an important time in the development of the immune system and an opportunity to reduce the risk of allergy in later life. If allergies run in your family, delay the introduction of allergic foods and maintain a nut- and seafood-free household in the early years.
Myth: Food colouring causes allergies
As the media spotlight turns again to how additives affect us, it looks like colouring falls into the category of intolerance rather than allergy, which can make it harder to pin down. Chemical additives used in food processing, such as colours, flavours and preservatives, can cause irritation of the skin, gut and behaviour in sensitive people. Interestingly, even more frequent and insidious are the problems some people have with reactions to naturally occurring characteristic flavours (salicylates, amines and glutamates) in food. Diagnosis can often be quite tricky, requiring an elimination diet followed by systematic reintroduction of foods to find the chemical culprit.
Myth: Allergies are caused by a weak immune system
Allergy is an immune system overreaction to substances that ordinarily pose no threat. It's a bit like calling in a SWAT team to answer a knock at the door. The immune system goes into action and releases a flood of chemicals that cause the discomfort of an allergic reaction. Don't consider taking any of the myriad of supplements that are marketed to boost or strengthen your immune system because they won't work.
Myth: Organic foods are non-allergenic
It isn't pesticides or additives that cause people to be allergic to foods but rather the proteins (a complex molecule) in the foods. So, limiting your diet to organic food is no guarantee you will avoid food allergies - an egg is still an egg, even if it has been organically produced. The immune system recognises the protein as a potential threat, even in very tiny amounts.
Myth: Allergies are nothing to worry about
Some allergies to foods, drugs and insect stings can be potentially life-threatening, with between 10 and 20 deaths in Australia every year. Beyond that, untreated allergies can have a significant impact on your quality of life. Less severe food allergies can produce uncomfortable symptoms such as colic, diarrhoea, an itchy rash around the mouth, hives or eczema. And hay fever can interfere with your sleep and make you feel tired throughout the day, more irritable and unable to think clearly.