Allergies: What's the cause?

Is it possible to have a mild food allergy that only brings on symptoms intermittently? I sometimes develop a runny nose and itchy throat soon after eating certain foods. The symptoms are mild and don't really trouble me, but it would be nice to know what causes them.

Dr Fred Kavalier answers your health question:

Allergies of all kinds are becoming more common in the UK. It may be because our environment is becoming cleaner. Without regular contact with germs, the body may be more likely to react to certain foods. A reaction that consists of a runny nose and an itchy throat definitely sounds allergic. There are cells in the throat and nose called mast cells. When these cells become sensitised to certain foods, they secrete chemicals such as histamine which cause the unpleasant symptoms. You could have some specialised allergy tests to find out the exact cause of the reaction. But if the symptoms are mild and not troublesome, it's not worth worrying about them. A severe food allergy will cause tongue swelling, wheezing and difficulty in breathing. This is a medical emergency that needs urgent treatment in a casualty department.

Please mail your questions for Dr Fred to health@independent.co.uk. He regrets that he is unable to respond personally to questions.