 Randomized controlled single center trial. Setting: Outpatient pediatric gastroenterology PG clinic, Childrens Hospital, London, Canada. Methodology: After a 4 week run in period, 60 children aged 5-18 years, meeting Rome 3 inclusion criteria for abdominal pain associated FGID will be recruited to the trial. After informed consent, the participants will be randomized to either a standard treatment or lifestyle modification dietary elimination group in the ratio of 1:1. IgG testing to food antigens will be completed in both groups using a commercially available specific IgG ELISA-based multiple food allergen panel but will ONLY be disclosed for the lifestyle modification group. The patient will receive specific advice by a dietitian to exclude a maximum of two food items from hisher diet for 4 weeks. Children will be followed-up in PG clinic at 4-weekly intervals for 16 weeks. At every clinic visit, Diary of food intake, Abdominal Pain Index API and Quality of Life QOL questionnaire will be completed by both child and parent. The standard therapy group will receive conventional treatment for Abdominal Pain AP as per usual practice at the PG Clinic. Response is defined as more than 50 improvement in frequency and severity of abdominal pain. At each follow up visit, non-responders will cross over to the other arm of the study. At the end of the trial, non-responders in either group will continue to receive conventional treatment in the PG Clinic. Responders will be discharged back to their family physicians. Data will be analyzed using IBM SPSS Statistics, version 22.0. 