One of the most common questions about food allergies is, “How many people have a peanut allergy?”
It is estimated that about four percent of teens and adults and five percent of children have food allergies, with less than one percent of Americans allergic to peanuts. Estimating the number of people with food allergies in the United States is a challenge, which means that current estimates are just that—the best approximations of the numbers of people with food allergies. In fact, according to a report from the National Academies of Sciences, Engineering and Medicine’s Committee on Food Allergies report Finding a Pathway to Safety’s Key Messages (National Academies of Sciences, Engineering, and Medicine; Health and Medicine Division; Food and Nutrition Board; Committee on Food Allergies, 2017), “There is no evidence of true prevalence of food allergy in the U.S.”
In this article, we’ll review some of the reasons the expert panel identified why it’s so difficult to establish an accurate prevalence number for food allergies in the U.S. We’ll explore limitations in diagnostic testing, disagreement over what to include under the umbrella of “food allergies,” and problems with the rigor of studies that have been done so far.
One of the main issues with ascertaining an accurate count stems from the inaccuracies in diagnosis. At present, there is no one laboratory test that can definitively diagnose food allergies. The NIAID specifically says that blood and skin tests alone are not diagnostic. In order to diagnose a food allergy, the process should start with having a history of a reaction.
The Panel Testing Problem
Unfortunately, panel allergy testing, where many foods are tested against at once, has been a problem. Blood and skin tests have a 50-60 percent false positive rate. This means that some people will test positive, even if they do not have any clinical symptoms of food allergies. In the absence of clinical symptoms, an individual is not considered allergic. The gold standard for diagnosing food allergies is a supervised oral food challenge. However, some doctors may determine these are not necessary if there’s a convincing history and positive skin and/or blood tests, or if an individual has already experienced a severe reaction, such as anaphylaxis. Sometimes, oral food challenges are hard to get because they come with the risk for severe reactions which families and practitioners may want to avoid and they may not be covered by insurance and are time intensive for the practitioner and family. In spite of these challenges to accessing them, oral food challenges remain the gold standard for diagnosis and are the only certain way to identify true food allergies.
What is and what is not a food allergy can be confounding when it comes to estimating prevalence. When consumers are asked about food allergies, they often equate any adverse food reaction to food allergies. Even some health professionals may be confused and include IgE mediated food allergies, non-IgE mediated reactions, oral food allergy syndrome, and even intolerances under the same umbrella. Sometimes even research studies lump together multiple conditions under the umbrella term of “food allergies” making it more complex. However, each of these has different diagnostic criteria and not all are considered true food allergies. While all of these conditions may involve the gastrointestinal tract, only IgE mediated food allergies has the potential for systemic involvement and anaphylaxis. All can cause discomfort, but only IgE mediated food allergies may be life-threatening.
The Unreliability of Self-Reported Data
Finally, the way in which studies have been done so far present some challenges. In particular, data was self-reported via phone surveys. Self-reported data is known to be unreliable because of potential bias. Since participants self-select to be in the study (or opt out), this method may over-select for participants with food allergies. In addition, because there is a lot of confusion about what is and is not food allergy, participants may claim to have allergies (or report on behalf of their child) yet may not truly have food allergy. According to the NIAID, 50-90 percent of self-reported food allergies are wrong (NIAID Sponsored Expert Panel, 2010).
Based on these challenges, it is clear why the experts deduced that we do not have a truly accurate understanding of the number of people with food allergies. In spite of the challenges associated with determining exact prevalence, testing, and defining them, food allergies are rightly a public health concern. More and better rigorous research is needed to gain a true estimate of food allergies. Until then, it’s important to remember that accurate testing is essential for the individual, as is support for the food allergy community.
National Academies of Sciences, Engineering, and Medicine; Health and Medicine Division; Food and Nutrition Board; Committee on Food Allergies. (2017). National Academies Press. Retrieved from https://www.nap.edu/catalog/23658/finding-a-path-to-safety-in-food-allergy-assessment-of
NIAID Sponsored Expert Panel. (2010). Guidelines for the Diagnosis and Management of Food Allergy in the U.S.: Report of the NIAID-Sponsored Expert Panel. J of Allergy Clin Immunol, S1-S58.