What Are Food Allergies & Sensitivities

What Are Food Allergies & Sensitivities

Food allergies are becoming more common, so we need effective food allergy tests to keep us informed and safe. Let’s see how testing works, including at home.

First of all, what is a food allergy? A food allergy is an unpleasant or unhealthy effect that occurs when you eat a certain food and your immune system has an adverse reaction to it (Boyce et al., 2011). Food allergies are surprisingly common: It is possible that as many as 30% of all children have a food allergy, with some commonly eaten foods being those to which children are most likely to be allergic (Pyrhönen et al., 2011).

There are several kinds of food allergy tests. One that is considered the gold standard, perhaps because it is as close to real-life testing as possible, is called an oral food challenge (Sampson et al., 2012). This kind of test is usually conducted in a doctor’s office and consists of giving the patient gradually increasing amounts of food to which they may be allergic. This is not something to be tried at home; the reason it happens in a doctor’s office is so that a medical provider with the ability to treat any kind of severe allergic reaction, such as anaphylaxis, is present and able to intervene immediately. This is considered a preferable approach because it is the most naturalistic of the food allergy tests and because a medical professional who can recognize signs and symptoms of an allergic reaction is able to witness them occurring (or not) in real time (Sampson et al., 2012).

A second type of food allergy test, which has been used often since the 1950s, is called skin prick testing (LaHood & Patil, 2019). In this method, a tiny amount of the food substance being investigated is applied to a person’s skin, and then the skin is pricked—not deep enough to draw blood but sufficiently so that the food substance can interact with the more vulnerable skin cells underneath the top layer. If the skin changes color and puffs up slightly, it indicates an allergic reaction.

The advantages of this method are that it can be performed easily with a variety of tools such as needles, and it puts the patient at lower risk of a severe allergic reaction (LaHood & Patil, 2019). This is also not something to try at home, as most doctors acquire the extracts of various foods from professional sources, use sanitized and sterile tools, and are familiar with how different reactions to the extracts will look—not things most people could be expected to comfortably pull off at home.

The most commonly used form of testing is a serum test, or blood test, in which cells from our blood are exposed to allergens and are observed to see whether they demonstrate an immune response (LaHood & Patil, 2019). While this does not prove that a person will have an allergic reaction to a real-life encounter with a certain food, it can strongly indicate whether their body has developed a strong immune response to certain foods.

“Food allergy is one of the least diagnosed and most prevalent causes of symptoms, especially depression.”
― Sherry Rogers

Food Allergy Causes

Why do we have food allergies in the first place? It seems that food allergies are related both to our genetics and to our experiences of not being exposed to certain foods as we grow up (Sampson et al., 2018). The genes we inherited from our parents may set us up to have allergic reactions to certain foods; we know this because studies of people who are twins have shown that people with more genes in common are more likely to share the same food allergy (Kivistö et al., 2019). At the same time, if our bodies do not get exposed to certain foods, we may become sensitized to them as well—a fact that has led some doctors to recommend exposing children early on to foods such as peanuts (Togias et al., 2017).

Food Allergy Action Plan

So, to be clear, a good action plan for determining one’s food allergies would start with consulting a medical professional (Lieberman & Sicherer, 2010) and following evidence-based protocols for figuring out what you are allergic to. Using other methods or going it on your own puts you at risk of eating something you really shouldn’t or eliminating foods from your life unnecessarily. After that, continue to follow your physician’s recommendations regarding whether to treat your allergy or simply avoid the food(s).

In Sum

Hopefully, this article helps you see that some aspects of food allergies are very clear while others aren’t. Immediate allergic reactions to foods should be pretty obvious, but there are lots of experiences we have that could result from a food sensitivity or from something else entirely. To my mind, this makes it important not to overthink the situation or go out of one’s way to find a food allergy (Bird et al., 2015), since other variables may be at play. Also, there is research to suggest that people perceive themselves to have food allergies at higher rates than they actually do have food allergies (Woods et al., 2002). All of this is to say, if you have not had alarming or very consistent allergic symptoms after eating a food, it may just be perfectly safe to eat.


● Bird, J. A., Crain, M., & Varshney, P. (2015). Food allergen panel testing often results in misdiagnosis of food allergy. The Journal of Pediatrics, 166(1), 97–100.

● Boyce, J. A., Assa’ad, A., Burks, A. W., Jones, S. M., Sampson, H. A., Wood, R. A., . . . & Schwaninger, J. M. (2011). Guidelines for the diagnosis and management of food allergy in the United States: summary of the NIAID-sponsored expert panel report. Journal of the American Academy of Dermatology, 64(1), 175–192.

● Kivistö, J. E., Clarke, A., Dery, A., De Schryver, S., Shand, G., Huhtala, H., . . . & Ben-Shoshan, M. (2019). Genetic and environmental susceptibility to food allergy in a registry of twins. Journal of Allergy and Clinical Immunology: In Practice, 7(8), 2916–2918.

● LaHood, N. A., & Patil, S. U. (2019). Food allergy testing. Clinics in Laboratory Medicine, 39(4), 625–642.

● Lieberman, J. A., & Sicherer, S. H. (2010). The diagnosis of food allergy. American Journal of Rhinology & Allergy, 24(6), 439–443.

● Pyrhönen, K., Hiltunen, L., Näyhä, S., Läärä, E., & Kaila, M. (2011). Real‐life epidemiology of food allergy testing in Finnish children. Pediatric Allergy and Immunology, 22(4), 361–368.

● Sampson, H. A., O’Mahony, L., Burks, A. W., Plaut, M., Lack, G., & Akdis, C. A. (2018). Mechanisms of food allergy. Journal of Allergy and Clinical Immunology, 141(1), 11–19.

● Sampson, H. A., Van Wijk, R. G., Bindslev-Jensen, C., Sicherer, S., Teuber, S. S., Burks, A. W., . . . & Chinchilli, V. M. (2012). Standardizing double-blind, placebo-controlled oral food challenges: American Academy of Allergy, Asthma & Immunology–European Academy of Allergy and Clinical Immunology PRACTALL consensus report. Journal of Allergy and Clinical Immunology, 130(6), 1260–1274.

● Togias, A., Cooper, S. F., Acebal, M. L. Assa’ad, A., Baker, J.R., Beck, L.A., . . . & Boyce, J. A. (2017). Addendum guidelines for the prevention of peanut allergy in the United States: report of the National Institute of Allergy and Infectious Diseases–sponsored expert panel. Journal of Allergy and Clinical Immunology, 139, 29–44.

● Woods, R. K., Stoney, R. M., Raven, J., Walters, E. H., Abramson, M., & Thien, F. C. K. (2002). Reported adverse food reactions overestimate true food allergy in the community. European Journal of Clinical Nutrition, 56(1), 31–36