A new British study in The New England Journal of Medicine has found that early introduction of peanuts to the diet may offer protection from the development of peanut allergy. The Learning Early About Peanut Allergy (LEAP) study, conducted by the National Institute of Allergy and Infectious Diseases (NIAID)-supported Immune Tolerance Network (ITN) tested the theory that the very low rates of peanut allergy in Israeli children was the result of early introduction of peanuts in the diet.
What We Know The prevalence of peanut allergy amongst children in Western countries has doubled in the past 10 years, reaching rates of 1.4 to 3.0% with approximately 1.7% of Canadian children allergic to peanuts. Peanut allergy is the leading cause of anaphylaxis and death due to food allergy . It also puts a substantial social and psychological (stress) burden on those with the allergy as well as their families. Research has demonstrated that peanut allergy develops early in life and is rarely outgrown. Clinical practice guidelines from the UK (1998) and from the US (2000) recommend the exclusion of foods known to result in serious allergic reactions from the diets of infants considered at high risk for allergy as well as from the diets of pregnant and breastfeeding women who have a family history of food allergy. The problem is that studies in which food allergens have been eliminated from the diet have consistently failed to show that elimination from the diet prevented the development of IgE-antibody mediated food allergy (the ‘gold-standard’ for diagnosis). As a result, in 2008, the previous recommendations for the avoidance of common serious food allergens were withdrawn — but the question remained as to whether early exposure or avoidance is the better strategy to prevent food allergies.
The Background to this Study Several years ago, the researchers of this study had observed that the risk of developing peanut allergy was 10 times higher amongst Jewish children in the UK as it was in Israeli children of similar age and ancestry. This observation was associated with a striking difference in the time at which peanuts are introduced in the diet in these countries: in the UK infants typically do not consume peanut-based foods in their first year whereas in Israel, peanut-based foods such as Bamba® are usually introduced in the diet early (at approximately 7 months of age). This finding led to the researchers hypothesizing that the early introduction of peanuts may offer protection from the development of peanut allergy. The Learning Early about Peanut Allergy (LEAP) study set out to determine whether the early introduction of peanut in the diet could serve as an effective strategy for the prevention of peanut allergy.
Study Subjects and Method Dr. Gideon Lack, a professor of pediatric allergy at King’s College London led the international team of researchers based on the idea that Israeli children have lower rates of peanut allergy compared to Jewish children of similar ancestry residing in the UK. The study tested the hypothesis that the very low rates of peanut allergy in Israeli children were a result of high levels of peanut consumption, beginning in infancy. In 2006, they recruited 640 children (mean age 7.8 months) who already had an egg allergy or eczema or both (indicators of children prone to a peanut allergy). The children aged 4- 11 months were divided into two groups. The first group of children did not have a peanut allergy in the initial skin-prick (RAST) allergy test while the second group of children had a weakly positive RAST test when the study began. These groups were then randomly assigned into two groups. In one group, the parents were asked to feed their babies peanut butter or Bamba® three times a week until the age of five years of age. The second group were instructed to keep their children’s diets peanut-free until age 5 years. Infants who were randomly assigned to eat peanut products were given an initial food challenge and further RAST allergy testing. Those who had negative results were given 2 g of peanut protein in a single dose and those who had a reaction to the peanut food challenge were instructed to avoid peanuts. Infants randomly assigned to consumption who did not have a reaction to the baseline challenge were fed at least 6g of peanut protein per week, distributed in three or more meals per week, until they reached 5 years old. Further clinical assessments occurred when the children were aged 4 – 11 months and at 1 year, 2 ½ years and 5 years old.
Source of Peanuts in the Study The preferred peanut source was Bamba®, an Israeli snack food manufactured from 50% peanut butter and puffed corn. Bamba® is the number one selling snack in Israel with 90% of Israeli families reporting buying Bamba on a regular basis. Smooth peanut butter was provided to children who did not like Bamba.
The Findings Among the 542 infants in the group with a negative result on the initial skin-prick test, 530 were included in the peanut eating group. At 5 years of age, ~ 14% of the peanut-avoiding group and 2% of the peanut-eating group were allergic to peanuts. This absolute difference in risk of 12 percentage points represents ~85% relative reduction in the prevalence of peanut allergy.
Significance of This Study The study indicates that the early introduction of peanut dramatically decreases the risk of development of peanut allergy and seems to indicate that something can be done to reverse the increasing prevalence of peanut allergy.
Word of Caution Parents of infants and young children with eczema or egg allergy or both should consult with an allergist, pediatrician or their General Practitioner before feeding them peanut products due to the increased risk of these children being allergic to peanut protein.
DuToit, G., Roberts, G., , D.M., Sayre, PH, Randomized Trial of Peanut Consumption in Infants at Risk for Peanut Allergy, N Engl J Med 2015; 372:803-813
Health Canada and AllerGen (Allergy, Genes, and Environment Network of Centres of Excellence), Canadian allergy prevalence study, 2008, http://www.hc-sc.gc.ca/fn-an/securit/allerg/res-prog/allergen_research-eng.php
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