When a little of what you fancy can be a real pain

However, chances are you’re actually one of the estimated 45 per cent of people in the UK who suffer from a food intolerance.

The two debilitating problems are often confused, but Food Allergy and Food Intolerance Week (January 24-28) hopes to clear up that issue and give sufferers more advice and information about their condition.

Cases of allergies are estimated to have tripled during the last 20 years. Allergy UK believes an allergic condition will affect around one in four people in the UK at some time in their lives, with numbers increasing by five per cent 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 unknown. 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.

She stresses that 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 relieve 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.

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 down food.

Some people are simply adversely affected by the chemicals that occur naturally in certain foods, which don’t affect other people.

TV doctor Dr Hilary Jones says:“For years, the orthodox medical profession has neglected the role of food intolerance in ill health.”

He is backing a test developed by YorkTest Laboratories, in York, which can help identify foods to which people may be sensitive. It includes a finger-prick blood-collection kit. The results, which are based on the presence and amounts of food-specific IgG antibodies, are analysed by scientists at YorkTest Laboratories.