You walk into the lunchroom, and all sorts of alarms go off in your head. While reaching for utensils you think “What if the last person used this for peanut butter and didn’t wash it well.” You sit down at the table thinking “Someone ate nuts here last week, was the table cleaned since then?” A coworker gleefully brings over homemade cookies. “Don’t worry, they don’t have peanuts! They’re chocolate chip cookies!” But you politely decline, trying to not hurt her feelings. You don’t know if the brand of chocolate chips was processed on the same equipment as peanut products. Experiences like these are a daily occurrence for the millions of individuals living with a food allergy.
Over 200,000 people in the US require emergency medical care for food allergies every year. Nearly half of these cases involve anaphylaxis: a severe reaction where the immune system perceives the allergen as a foreign invader, triggering a response where inflammatory mediators such as histamine are released. Symptoms include throat swelling, shortness of breath, and low blood pressure that can lead to death if untreated. Anaphylaxis onset is rapid, occurring within minutes to hours following allergen exposure so access to immediate treatment is crucial. Fortunately, treatment with Epinepherine, antihistamines, and other steroids can effectively and rapidly reverse this reaction. Individuals prone to anaphylactic reactions are often prescribed an Epipen which serves as the first line of treatment following allergen exposure, though additional treatment and monitoring is necessary.
Due to psychological impacts, reaction severity, and cost of medical intervention including Epipens, preventing allergen exposure is ideal. Unfortunately, this is easier said than done. The minimum dose of an allergen that can trigger a reaction is often low. Peanuts are one of the top 8 allergenic foods, with 0.5%-1% of the population exhibiting an allergic response. About 50% of peanut-allergic individuals experience a reaction after ingestion of 100 mg peanut protein, or less than one peanut kernel, while about 5% exhibit a reaction upon exposure to as little peanut protein as is in less than 1/100th of a kernel!
Even if foods explicitly stated to contain peanuts are avoided, cross contact can still cause exposure of doses high enough to elicit an allergic reaction. Cross contact, when an allergen is transferred from a food containing that allergen to one that does not, often occurs in factories and cooking settings. If a company packages peanuts, peanut traces can remain on equipment not properly cleaned. Other products loaded using this equipment may now contain peanut traces. Even the most vigilant can be affected, reflected in the fact that nearly half of emergency medical treatments for food allergies follow accidental exposure.
While there are no clinically approved treatments for food allergies, there has been recent success in an experimental treatment providing oral immunotherapy to peanut-allergic individuals. This process refers to feeding an increasing amount of allergen over time to increase the threshold that triggers a reaction. This regular low-dose allergen ingestion trains the immune system to become desensitized, a similar concept to how vaccines train the immune system to handle foreign invaders. A phase 3 clinical trial indicated oral immunotherapy with a peanut allergen-derived drug increased the amount of peanut protein youth and adolescents could tolerate without an allergic reaction. This potential therapy is undergoing review by the FDA, with a decision expected around Fall 2019. This parallels recent findings that early introduction of peanut products to babies may decrease their likelihood of developing a peanut allergy. It is unclear exactly how peanut allergies develop, though it is theorized to stem from a combination of genetic and environmental influences.
This trial provides imminent hope for treatment, though it certainly should not be regarded as a cure. Oral immunotherapy serves to increase the allergen dose required to trigger a reaction, as opposed to preventing a reaction from occurring. It would likely be successful in reducing the prevalence of reactions caused by accidental exposure to low allergen doses, but not allow an individual to eat allergen-containing foods to their hearts desire. While development of treatments for food allergies will significantly improve the lives of individuals living with them, increased awareness and understanding how to prevent accidental exposure can compliment these efforts.
About the Author
Emily is a PhD candidate in the Department of Microbiology studying a regulator of aromatic compound metabolism in the soil bacterium Acinetobacter baylyi. She loves running, college football, and taking her dog everywhere around Athens. You can reach her at firstname.lastname@example.org. More from Emily McIntyre.