After the first consultation with the medical investigator, a skin prick test and/or blood tests for specific immunoglobulin E (IgE) to eight major food allergens will be tested, namely cow's milk, egg, peanut, treenuts, wheat, soya, seafood, shellfish. Subject will consult a dietitian for either a well-balanced diet (CG) or low histamine diet (TG) and he/she is asked only to start the diet one week after the first consultation. The subject will be asked to fax or email his/her completed questionnaire and food diary for checking before he/she starts the diet. Dietitian will ensure that the questionnaire and the food diary are completed correctly by the subject. Dietitian will then phone the subject not only to remind him/her to start on the diet but also to make sure that the subject corrects any errors in completing the questionnaire and food diary. If the diary during the run in period is done very poorly it may have to be repeated before the formal diet begins. Dietitian will conduct subsequent weekly phone follow up with each subject. Each subject will be reminded to complete their questionnaires and food diaries every evening.