Go out to a restaurant with friends, or take your child to a birthday tea and chances are there will be someone there who cannot eat something because they have a food allergy.
But true allergic reactions to food are actually far less common than most of us imagine, according to Professor Barry Kay, Consultant Allergist at the London Clinic. 'Food allergy, which happens when someone eats a particular food and their immune system produces what we call IgE antibodies, causing a particular set of symptoms [see 'Symptom Watch'] immediately or shortly after eating the offending food, is clear-cut, uncontroversial and can be confirmed scientifically by an allergy test,' he says.
'It can also be extremely serious.' In fact, if you have a severe food allergy, eating even a minute amount of the wrong food causes a reaction called anaphylaxis: breathing difficulties, swelling of the lips and throat, abdominal pain, vomiting, collapse and, in the worst-case scenario, it can lead to death.
Allergy or intolerance?
Experts still don't know how many of us are affected by food allergy, but it appears to be on the rise. 'The trouble is that many people who believe they have a food allergy are actually experiencing food intolerance, or non-allergic food hypersensitivity,' says dietitian Helen Bond, a spokesperson for the British Dietetic Society.
'In fact, although around 30 per cent of people claim to be allergic to one or more foods, only 1 to 2 per cent of adults have a true food allergy and 5 to 8 per cent of children. But, food intolerance is far more common and may affect as many as 45 per cent of people according to some estimates,' she adds. While food allergies normally occur in reaction to a fairly limited number of foods, (see '10 Common Culprits') food intolerance reactions are more idiosyncratic and occur when you eat foods that most people can tolerate without a problem making them quite hard to diagnose.
As Dr Anton Emmanuel, Consultant Gastroenterologist, senior lecturer in Neuro-gastroenterology at University College, London, and expert adviser to Food Intolerance Awareness, part of AllergyUK, explains: 'The main problem is that food intolerance is unpredictable: sometimes a reaction happens and sometimes it doesn't, while symptoms are wide-ranging and can be vague, although often they affect the digestive system.'
Symptoms of food intolerance can be caused by lack of the enzymes needed to digest certain foods, e.g. lactase, an enzyme needed to digest the milk sugar lactose, causing lactose intolerance. They can also be caused by an abnormal sensitivity to certain ingredients in foods, additives and preservatives, such as tyramine, found in mature cheeses and yeast extract as well as certain wines that causes migraine. Alternatively they may be toxic reactions to food (e.g. food poisoning).
Meanwhile, coeliac disease, which is not an allergy or an intolerance at all but a unique and complex immune reaction, can trigger symptoms (see 'Symptom Watch') when an affected person eats gluten, which is a protein found in bread, pasta, biscuits, and a host of other foods containing wheat, barley, rye and, to a certain extent, oats. This damages the surface of the gut, thereby making it hard to absorb certain nutrients.
10 Common culprits
You can get an allergic reaction to any food, but these are the top offenders...
- Peanuts and products containing peanuts
- Soya and soya products
- Egg and egg products
- Milk and milk products
- Fish and fish products
- Wheat and products containing wheat
- Shellfish (e.g. shrimps, prawns, lobster, crab, crayfish, clams, mussels, oysters and scallops)
- Fruit - apples, pears, kiwi fruit and peaches are common culprits in adults
- Vegetables - potatoes, carrots, celery and parsnip in adults
- Tree nuts and products containing tree nuts - almonds,Brazils, hazelnuts, cashews, macadamia, pecan, pine nuts, pistachios, and walnuts