The beloved Israeli snack, Bamba, might soon lose its Israeli roots and relocate to Switzerland. However, its health contributions, particularly in reducing the risk of peanut allergies, remain a source of national pride.
In 2008, a British-Israeli study revealed peanut allergies are significantly less common among Israeli children compared to Jewish children in Britain with similar genetic backgrounds. This led an international team of researchers to investigate whether early exposure to peanuts could prevent life-threatening allergies later in life.
Recently, the New England Journal of Medicine published the latest findings from this research, which has been ongoing for over 15 years. About 640 infants, aged four to eleven months, who showed tendencies to develop various allergies like eczema and egg allergies—thus at higher risk for peanut allergies—were selected for the study.
What triggers a peanut allergy?
A peanut allergy arises from an inappropriate immune response to a protein found in peanuts, causing symptoms from runny noses to anaphylactic shock, which can be fatal if untreated. The prevalence of this allergy is high (between one to two percent) and rising in the Western world. The challenge in managing it lies in the widespread presence of peanuts or their traces in various foods, making avoidance difficult.
Each year, 7% to 14% of those allergic inadvertently encounter peanuts, and a third of them experience anaphylactic shock. Frustratingly, unlike many childhood food allergies that diminish over time, a peanut allergy often persists into adulthood.
How was the study conducted?
Initially, researchers identified which infants were already sensitive to peanuts using a skin test. This involves pricking the skin, applying various allergens, and measuring skin swelling around the pricks to determine sensitivities—much like determining which pollen makes you sneeze in spring.
The study then continued with two groups: those whose skin swelled, indicating peanut sensitivity, and those who did not. Each group was split into two: one that regularly consumed Bamba until age five, and one that did not.
A few years into the study, when the children were five, they were tested for peanut allergies using a challenge test, where they consumed a measured amount of peanut protein under supervision. Symptoms were monitored, and blood tests assessed antibodies to peanut proteins and those that suppress immune reactions to peanuts. Children allergic to peanuts have high levels of antibodies to peanut proteins compared to suppressing antibodies.
It was found that peanut allergy rates were significantly lower in groups exposed to Bamba early compared to those who avoided peanuts. Additionally, some children who initially showed sensitivity in infancy became completely non-allergic to peanuts by age five due to Bamba exposure.
In follow-up stages, researchers revisited the children, now 12 years old, more than 11 years after they entered the study, to see if Bamba’s allergy resistance persisted into adolescence.
"Researchers estimate that early peanut exposure reduces the chance of developing an allergy by about 75%. Moreover, since the effect of early exposure lasts several years, they assume the children’s acquired resistance will last a lifetime."
The allergy prevalence among children consistently exposed to Bamba until age five was significantly lower than among those who avoided it. This was true even for those who initially showed a skin reaction to peanuts: some outgrew the allergy entirely by age 12.
To confirm that exposure until age five is sufficient to establish resistance regardless of later exposure levels, some children were advised to avoid peanuts entirely between ages five and six. Early exposure still protected these children against allergy development.
By considering all trial groups, researchers estimate that early peanut exposure reduces allergy risk by about 75%. Since the lasting effect of early exposure was proven, researchers assume the children’s acquired resistance will last a lifetime. To validate this hypothesis, they plan to check back with the children later in life to monitor any allergy development.
Professor Arnon Elitzur, Chairman of the Israel Association of Allergy and Clinical Immunology, remarked that this research is indeed pivotal in our approach to early exposure to allergenic foods as a means to reduce food allergy risks. "Similar efficacy was later found for eggs, and we assume it applies to other allergenic foods. The latest study in the series, recently published, tracked subjects until age 12 and demonstrated that regular peanut consumption until age five significantly reduces peanut allergy risk even 12 years later, despite irregular post-age five consumption with long exposure gaps."
Key takeaways:
- An allergic reaction does not automatically lead to an allergy: Some children had positive skin tests for peanuts at the study's start but could still consume peanuts. This indicates low specificity of these tests, and a positive skin test without a reaction history doesn’t necessarily mean an allergy to that food.
- Allergies can develop later in life: The largest difference in peanut allergy rates was between children with positive skin tests who avoided peanuts (34%) versus those who consumed them (0%). This highlights that, while waiting for a challenge test (about a year), there’s a high chance a child with a positive skin test may develop an allergy to that food, even if initially non-allergic.
- Testing children only for suspected allergenic foods is recommended: It’s not advisable to conduct skin tests for foods regularly consumed or not yet eaten. Similarly, blood tests for food-specific IgE antibodies should only be conducted for foods suspected of causing an allergic reaction, upon referral by an allergy and immunology specialist.