Going nuts over infant peanut exposure

Peanut allergies are becoming more widespread across the globe^[1]. In the United States, up to 1.4% of the population^[2], or as many as 4.4 million people have a peanut allergy. Peanut exposure is one of the leading causes^[3] of allergy-related deaths due to anaphylaxis, a set of symptoms that can include facial and oral swelling, difficulty breathing, a dangerous drop in blood pressure, and cardiac arrest. Other less severe symptoms include itchy skin and mouth, hives, and gastrointestinal distress.

Unlike some other food allergies, like milk, soy, and egg, a peanut allergy rarely lessens with age^[4]. While there has been a lot research^[5] into possible therapies, there is currently no treatment other than complete avoidance, which requires hypervigilance in case of cross-contamination of other foods, leading to trace amounts of peanut in foods that would otherwise be assumed as safe. Many current research efforts focus instead on ways to prevent the development of severe allergies like this one. Researchers discovered^[6] that dietary antigens (foreign substances that trigger the immune system to respond) for allergenic foods can pass through the placenta to the fetus, as well as pass through breast milk to an infant. Based on this finding, they hypothesized that preventing this early exposure would reduce the incidence of food allergies.

For most of the first decade of the 21st century, women were advised^[7] to avoid possible allergy triggers like peanuts, dairy, and egg during their pregnancies, as well as to avoid feeding them to their infants. In spite of these efforts, epidemiological data^[2] show that the incidence of allergies actually increased. In fact, a meta-analysis of studies^[8] following children whose mothers had avoided dietary allergens found that those children developed allergies at approximately the same rate as children whose mothers did not adhere to the dietary recommendations. As a result, the recommendation to avoid dietary allergens during pregnancy was later abandoned. Figure 1 notes some milestones from the past few decades with regards to peanut allergy.

Figure 1: Peanuts: from snack darling to object of constant vigilance

Source: Sicherer et al., J Allergy Clin Immunol. 2010.

The increase in allergy rates in response to avoiding certain foods raises the question of whether deliberate exposure to potentially allergenic foods could reduce the incidence of allergies. This study was designed to investigate this question in the context of peanut allergies in infants.

The number of people with a peanut allergy is increasing worldwide, which can result in a serious and sometimes life-threatening allergic reaction. Previous recommendations for mothers to avoid allergens during pregnancy and breastfeeding did not prevent the rise in allergies in children. The purpose of this study was to see if consumption of peanuts at an early age might help prevent development of peanut allergies in children.