The number of people with allergies is increasing at an alarming rate. Ahead of Food Allergy and Intolerance Week (January 24-28), experts explain why more of us are having allergic reactions, and what the common triggers are.
By Lisa Salmon
If eating cheese always gives you a migraine, you might assume you're allergic to it.
However, chances are you're actually one of the estimated 45% of people in the UK who suffer from a food intolerance.
The two debilitating problems are often confused and Food Allergy and Food Intolerance Week (January 24-28) hopes to clear that issue up and give sufferers more advice and information about their condition.
Considering cases of allergies are estimated to have tripled during the last 20 years, their guidance is clearly much needed.
Allergy UK believe an allergic condition will affect around one in four people in the UK at some time in their lives, with numbers increasing by 5% each year, and as many as half of those sufferers are children.
A food allergy happens when a person's immune system immediately reacts in a negative way after the offending food has been eaten, or sometimes even touched or smelled.
The immune system mistakenly believes allergens - the substance in the food that causes the reaction - to be damaging and produces an antibody (IgE) to attack it.
This leads other blood cells to release further chemicals, including histamine, which together cause the symptoms of an allergic reaction.
Allergy symptoms can range from a slight rash or runny nose, wheezing, itching, severe abdominal problems and sudden collapse, to the most severe reaction, anaphylaxis.
However, when it comes to food intolerance symptoms - such as fatigue, bloating and irritable bowels - they're nearly always delayed, taking hours, and sometimes even a day or two, to appear.
Lindsey McManus, executive director of Allergy UK says: "The word allergy is used to describe an adverse reaction, but people don't understand the difference between food allergy and food intolerance."
"Working out the difference is hard and the word does tend to get bandied about wrongly."
While allergies can sometimes be hereditary, the reason for their dramatic rise is also opaque. There are a number of theories, including the possibility that dietary changes, such as eating less fruit and vegetables, may be responsible.
Another theory is that children are increasingly growing up in 'germ-free' environments, meaning their immune systems may not get enough exposure to develop properly.
McManus stresses people can develop a food allergy or intolerance at any time: "They can have enjoyed a particular food all their life and suddenly won't feel very well as a result of eating it. A trigger can be illness or high stress."
The level of danger from allergies varies widely. Anaphylactic sufferers carry adrenaline injections. A quick dose of the hormone will improve potentially fatal symptoms such as swelling of the throat and mouth, difficulty in swallowing, speaking or breathing, nausea and vomiting, a drop in blood pressure and unconsciousness.
When it comes to less severe allergic reactions, treatment usually involves anti-histamines, or occasionally steroids.
"Fortunately full-blown anaphylaxis is quite rare, but with any allergy people may not be able eat certain foods, as they may get swollen lips, rashes or breathing problems," says McManus. "Allergies really can make life miserable, and sometimes even dangerous, for people."
Less severe food intolerance responses are relatively common. Symptoms which also include joint pain, rashes, eczema and migraine can occur for many reasons, such as eating the same food too often, having a hectic lifestyle so food isn't digested properly, or lacking the enzymes to break food down.
Some people are simply adversely affected by the chemicals that occur naturally in certain foods, which don't affect other people.
Unfortunately, there are no easy blood or skin-prick tests to identify intolerance, except for one or two well-researched problems such as gluten and lactose intolerances.
Some tests have been developed that may be helpful in identifying intolerances, but none give a definite answer.
McManus says: "It's extremely difficult to get a diagnosis - GPs have little or no knowledge of food allergy. And it's even more difficult to pinpoint the problem with food intolerances, the mechanism behind it is very poorly understood."
She says there's a real lack of allergy clinics in the UK and people who suspect they have a problem with certain foods should contact their GP or Allergy UK.
If you think they have a problem with a particular food, the charity recommends you write a food symptoms diary, including everything you eat for two or three weeks, together with your symptoms, to see if there's a pattern.
McManus says it's best to compile a food diary under the guidance of experts at Allergy UK, or a GP - particularly if the reaction is severe. Then you can look at eliminating foods.
"People really do need proper advice and help if they suspect an allergy or food intolerance," she stresses.
"While food intolerance can make you pretty miserable, food allergy has the potential to kill, so you have to be very careful."
Could you be allergic?
According to Allergy UK, these are the foods which commonly cause allergies...
:: Nuts and seeds
:: Shellfish and fish
:: Some fruits such as citrus and kiwi
:: For more information about allergies and food intolerance visit www.allergyuk.org.