Student research

by
Natalie Saunders
Master of Science (Nutrition and Dietetics), University of Wollongong
Supervisors: Linda Tapsell, Anne Swain, Velencia Soutter, Robert Loblay
November 1997

Full Text - PDF (347 KB)

Introduction:
It is well documented in the literature that many people with eczema also have a food allergy. A food allergy is defined as an adverse reaction to food, involving the immune system. While the prevalence of true food allergy is difficult to determine, the presence of a positive skin prick test (SPT) indicates the child has been sensitised to that food. The primary aim of this project was to investigate in children with eczema; food sensitisation, most common sensitising foods, clinical reactions to foods, associated symptoms, and family history of allergic disease. The secondary aim was to investigate the natural history of food allergy, in particular peanut allergy. It has been suggested that the prevalence of peanut allergy is increasing, however controversy exists as to the actual reason for this. Numerous studies indicate that most children will grow out of their food allergy, however evidence suggests many children do not grow out of their peanut allergy. Peanut is also the leading cause of food induced anaphylaxis. A final aim of this study is to investigate severe food reactions in children with eczema.

Methods:
Data was collected from medical and dietetic notes of 418 children with eczema aged up to 12 years seen at the RPAH Allergy Unit between 1995 and 1997. Parents and carers were sent a questionnaire to obtain additional information about the child's symptoms, food allergen avoidance and clinical reactions to foods. All information was entered into a confidential database for analysis. To investigate the natural history of peanut allergy, those children with a positive SPT to peanut at first presentation to the clinic were invited back in for a follow up SPT.

Results:
Approximately half of all children with eczema were sensitised to one or more foods. The most common food allergens were egg, peanut, milk, fish, wheat, sesame and soy. The most common symptoms associated with food sensitisation and eczema were asthma and rhinitis. Peanut sensitisation was present in one third of the children with eczema. Peanut sensitisation tends to persist in children longer than other food allergens. There is a trend for food sensitisation to decrease and aero-allergen sensitisation to increase with age. Peanut and milk were the most common foods causing anaphylaxis.

Discussion:
To determine the actual role food allergy plays in eczema is beyond the scope of this study, however results indicate food sensitisation is common. The prevalence of peanut sensitisation is one of concern particularly due to the often severe nature of reactions and the persistence of allergy into adulthood. These children require special care and attention and parents and carers should be educated on how to avoid or reduce the risk of exposure to allergens and suitable procedures in the event of accidental exposure to food allergens.