A food allergy occurs when the body’s immune system mistakenly identifies a food protein as harmful. This protein, known as an allergen, triggers an immune response that can cause a range of symptoms. When someone with a food allergy eats, touches, or inhales an allergen, their immune system produces a specific type of antibody called IgE.
These IgE antibodies circulate in the blood and attach to immune cells. The next time the person encounters the same allergen, it binds to the IgE antibodies, prompting the immune cells to release chemicals like histamine. These chemicals are responsible for the various symptoms associated with food allergies.
The location where these chemicals are released determines the specific symptoms that manifest. For instance, if the chemicals are released in the skin, they can cause hives, itching, and redness. In the respiratory system, they might lead to difficulty breathing, wheezing, or a runny nose.
Unanswered Questions About Food Allergies
Despite significant progress in understanding food allergies, many questions remain unanswered. Researchers are actively investigating these areas to develop better prevention and treatment strategies. Some key questions include:
- Why do some individuals develop IgE antibodies to certain foods while others do not? Genetic predisposition, environmental factors, and early childhood exposures are all being explored as potential contributing factors.
- Why do some individuals with IgE antibodies to a food allergen not experience an allergic reaction? This phenomenon, known as tolerance, is not fully understood, but it may involve mechanisms that suppress the allergic response.
- Why do some individuals with food allergies experience severe reactions, while others have milder symptoms? The severity of an allergic reaction can depend on various factors, including the amount of allergen consumed, the individual’s sensitivity, and the presence of other health conditions.
Researchers hope that by finding the answers to these fundamental questions, more effective ways to prevent food allergies or reduce the severity of allergic reactions can be developed.
The Evolution of Food Allergy Prevention Strategies
For many years, healthcare professionals advised parents to delay introducing potentially allergenic foods to infants. However, this approach has changed over time due to new research findings.
Initially, the American Academy of Pediatrics in 2008 concluded that there was insufficient evidence to support delaying the introduction of allergenic foods beyond 6 months of age as a means of preventing food allergies. This was a significant shift from previous recommendations.
A landmark study called Learning Early About Peanut Allergy (LEAP), funded by the National Institute of Allergy and Infectious Diseases (NIAID), revolutionized our understanding of peanut allergy prevention. The LEAP study results in 2015 demonstrated that introducing peanut-containing foods to infants before their first birthday significantly reduced their risk of developing peanut allergy by the age of 5.
Specifically, children who consumed peanut products early in life were 80% less likely to develop peanut allergy compared to those who avoided peanut until age 5. This groundbreaking finding led to a complete reversal of the previous advice.
Further research by the LEAP team showed that the protective effect of early peanut consumption was long-lasting. Children who had consumed peanut early in life were still less likely to develop peanut allergy even when they avoided peanut consumption between the ages of 5 and 6.
Long-term follow-up studies of the LEAP participants into adolescence confirmed the sustained benefits of early peanut introduction. The tests showed that regular, early peanut consumption reduced the rate of peanut allergy in adolescence by 71% compared to early peanut avoidance. The findings were published in May 2024.
The Role of Skin Exposure in Peanut Allergy Development
The LEAP study also provided insights into how peanut allergy might develop. Researchers observed that some infants in the peanut avoidance group became sensitized to peanut at a young age. They hypothesized that exposure to trace amounts of peanut through the skin could contribute to this sensitization.
This observation highlights the importance of considering all routes of allergen exposure, not just ingestion, when trying to understand and prevent food allergies.
Updated Guidelines for Peanut Allergy Prevention
Based on the compelling evidence from the LEAP study, NIAID spearheaded the development of Addendum Guidelines for the Prevention of Peanut Allergy in the United States, which were published in January 2017. These guidelines recommend introducing peanut-containing foods to infants as early as 4-6 months of age, depending on their individual risk factors.
Since the publication of these guidelines, research has expanded to include other allergenic foods, such as milk and eggs. Studies suggest that early introduction of these foods may also help prevent food allergies. As a result, many countries are broadening their guidelines to include foods beyond peanut. These evolving recommendations reflect the growing understanding of the importance of early allergen exposure in preventing food allergies.
