Food allergy symptoms can range from itchiness and swelling to a full-blown medical emergency. But no matter where you are in your reaction level, we can all agree that there’s nothing beneficial about an allergy — right? Actually, surprising new research suggests that food allergies have a protective effect against COVID-19.
Published in the Journal of Allergy and Clinical Immunology, the study found that people with food allergies are at a lower risk of COVID-19 infection as compared to those without them.
Understanding the Research
The researchers set out to determine whether people with food allergies, asthma, eczema, or allergic rhinitis were more likely to get COVID-19. So, they recruited volunteers from 1,394 households (4,142 people total participated in the study). About half of the participants claimed to have a food allergy, asthma, eczema, or allergic rhinitis. The study authors confirmed these conditions with doctor diagnoses and blood tests.
Twice a week for six months — in a time period between May 2020 and February 2021 — each volunteer had to provide a nasal swab. (Some nasal swabs were self-collected, and some were taken by care providers, such as parents.) If a participant tested positive for COVID-19 at any point, more nasal swabs and blood samples were taken.
At the end of the six months, 147 households (261 participants) had tested positive for COVID-19. Age didn’t affect transmission rates — so children got infected at a rate similar to teens and adults. (However, children were far less likely to have symptoms than adults.)
Unexpectedly, households that had an individual with a food allergy experienced lower transmission rates. In fact, food allergies were linked to a 50 percent lower risk of getting infected. Asthma, allergic rhinitis, and eczema did not appear to increase or decrease the risk of infection.
The Link Between Food Allergies and a Lower Risk of COVID-19
Why might food allergies reduce a person’s risk of being infected with COVID-19? According to Max A. Seibold, PhD, lead National Jewish Health investigator and the study’s first author, it might have to do with inflammation already present in the body — specifically, type 2 inflammation.
Type 2 inflammation is a normal immune response to infection, parasites, and (in some people) allergic conditions like food allergies. Dr. Seibold and his team theorize that this type of inflammation reduces the ability of COVID-19 to enter cells.
“Our findings … suggest underlying inflammation is an important determinant of susceptibility to SARS-CoV-2 infection,” Dr. Seibold said in a press release.
What These Research Results Mean
Now, this research does not necessarily mean that having a food allergy will protect you from getting COVID-19. It also does not mean that having a food allergy protects you from a serious infection — the researchers only tested infection rates, not severity of illness.
In addition, the study had some limitations. It took place before most people had a vaccine, so a similar study conducted now could yield very different results. Also, the team didn’t analyze as many nasal swabs as they had meant to (potentially because participants and caregivers didn’t always send them in). This could have caused the study authors to underestimate the number of COVID-19 infections. It may also have caused them to underestimate the risks linked to asthma and other conditions.
Furthermore, some households were more likely to get COVID than others — particularly households in which children or teens went to school. Lastly, those who lived in a food-allergy household could have been better at preventing transmission (cleaning high-touch surfaces regularly, for example), because they were already careful about cross-contamination of food.
Still, the research is important, because it gives us valuable insight into risk factors for infection. The authors also argue that this study provides some of the strongest evidence to date that asthma isn’t a risk factor. Someday, the research may also help scientists develop new ways of preventing transmission.