Du Toit G, Katz Y, Sasieni P, et al. J Allergy Clin Immunol. 2008;122(5):984–991
PURPOSE OF THE STUDY. To determine the prevalence of peanut allergy (PA) among Israeli and United Kingdom Jewish children and to evaluate the relationship of PA to peanut consumption by infants and mothers.
STUDY POPULATION. The study included Jewish children between the ages of 4 and 19 years who attended targeted primary and high schools. Eligible Jewish schools in greater London, United Kingdom, and Israeli schools in the Mehoz Merkaz region of Tel Aviv were selected because they were thought to represent comparable residential environments. The mothers of Jewish infants 4 to 24 months of age in general practitioner clinics in the United Kingdom and Tipat Halav clinics in Israel were also surveyed about the timing of ingestion of peanut.
METHODS. Two validated questionnaires were used. The Food Allergy Questionnaire was completed by high school pupils and by parents on behalf of primary school pupils; it asked about allergies to cow's milk, hen's egg, sesame, peanut, tree nuts, asthma, hay fever, and eczema and parental occupation. The Food Frequency Questionnaire, a validated consumption questionnaire given to mothers in the waiting room, made a detailed determination of peanut, sesame, and other solid-food consumption during the child's first year and by the mother during pregnancy and lactation. All children with a questionnaire-based diagnosis of PA were invited for allergy testing; PA was confirmed if skin-prick test results, specific immunoglobulin E (IgE) measurements, or both were greater than the 95% positive predictive values or if children had a positive oral peanut-challenge result.
RESULTS. The Food Allergy Questionnaires were distributed to 10 786 children, and 81.8% were returned. Mothers returned 176 Food Frequency Questionnaires; none declined participation. The prevalence of PA in the United Kingdom was 1.85% and that in Israel was 0.17% (P < .001). After adjustment for atopy, the relative risk for PA in the United Kingdom was 5.8 (95% confidence interval: 2.87–11.8) for all children and 9.8 (95% confidence interval: 3.1–30.5) for primary school children. In terms of dietary assessments, the Kaplan-Meier plots for the age of introduction of solid foods were similar in the 2 countries; the introduction of egg, soybean, wheat, vegetables, fruits, and tree nuts was similar. However, with the introduction of peanut there was a significant difference between the 2 countries; by 9 months of age, 69% of Israelis were eating peanut, compared with only 10% of United Kingdom infants. The median monthly consumption of peanut in Israeli infants 8 to 14 months of age was 7.1 g of peanut protein and that in United Kingdom infants was 0 g (P < .001). Similar contents of major peanut allergens were demonstrated in products from the 2 countries, as well as similar levels of IgE binding between the products.
CONCLUSIONS. The prevalence of PA is 10-fold higher in Jewish children in the United Kingdom, compared with that seen in Jewish children in Israel. The differences cannot be explained by differences in age, gender, ancestry, atopy, or socioeconomic class. The most obvious difference in the diet of infants in the 2 populations occurs in the introduction of peanut. Israeli infants are introduced to peanut during early weaning and continue to eat peanut more frequently and in higher amounts than United Kingdom infants, who avoid peanut. It has been proposed that different methods of preparing peanut could be responsible for the different rates of PA in different countries, but commonly consumed peanut-containing foods in both countries are derived from roasted peanut butter, and equivalent amounts of total protein, major peanut allergen, and IgE binding were demonstrated among these foods.
REVIEWERS COMMENTS. This study demonstrated a strong inverse association between peanut consumption in infancy and the prevalence of PA in childhood. It is compelling that the early introduction of frequent and high doses of peanut protein in infants may lead to oral tolerance. Although there is inherent selection bias and recall bias with questionnaires in general, the authors of this study attempted to reduce both of these factors. Until recently, dietary avoidance of peanut during pregnancy, breastfeeding, and early childhood was recommended in the United States. This article prompts us to question our practices and recommendations in terms of introduction of peanut into our children's diet and how it may affect their propensity to develop PA. An ongoing study, Learning Early About Peanut Allergy (LEAP), which is being conducted by the authors of this article, should provide much-needed evidence for guidelines on the introduction of peanut into the diet of infants and children.
- Copyright © 2009 by the American Academy of Pediatrics