The US study also confirmed that being overweight or obese increases the risk of coronavirus infection.
Food allergies can be a nuisance at best, and a serious health hazard at worst.
There is, however, one advantage for people who have a food allergy: They may be better protected from COVID-19
A study funded by the National Institutes of Health (NIH) in the United States has found people with food allergies are less likely to become infected with SARS-CoV-2, the virus that causes COVID-19, than people who don’t have them.
The Human Epidemiology and Response to SARS-CoV-2 (HEROS) study followed more than 4,000 people in nearly 1,400 households in the US, and along with food allergies, it looked at the effects of obesity, high body mass index (BMI), asthma, and how the virus affects children under the age of 12.
The researchers found those who had a self-reported, doctor-diagnosed food allergy had a 50 per cent lower risk of getting infected with coronavirus than those without food allergies.
It was hypothesised that people with food allergies may have a lower risk of catching the virus because they tend to dine out less than the general population, but the researchers found that households with food-allergic participants had only slightly lower levels of community exposure than other households.
Dr Tina Hartert, a professor of medicine and pediatrics at the Vanderbilt University School of Medicine in Nashville, and co-lead of the research, speculates that a “type 2 inflammation” which is characteristic of allergic conditions, could reduce levels of a protein called the ACE2 receptor on the surface of airway cells.
Coronavirus uses this receptor to enter cells, so its scarcity could limit the virus’s ability to infect them.
How asthma and obesity affect COVID risk
One of the most common forms of asthma is allergic asthma, triggered by allergens like pollen, pets and dust mites.
But unlike for those with food allergies, the HEROS study didn’t find that people with allergic asthma had a reduced risk of coronavirus infection. It found asthma does not increase the risk of infection, either.
The study did however confirm an increased risk factor from obesity or a high BMI, which previous studies had suggested.
The authors found a strong, linear relationship between BMI and COVID risk: Every 10-point increase in BMI percentile - which shows how a person’s body fat compares to that of other people the same age and gender - raised the risk of infection by 9 per cent.
Participants who were overweight or obese had a 41 per cent greater risk of infection than those who were not.
One other important finding was that children aged 12 or younger are just as likely to become infected with the virus as teenagers and adults, but 75 per cent of infections in children are asymptomatic.
Dr Anthony Fauci, the chief medical advisor to US President Joe Biden and the public face of the country’s coronavirus vaccination campaign, said the study findings “underscore the importance of vaccinating children and implementing other public health measures to prevent them from becoming infected with SARS-CoV-2, thus protecting both children and vulnerable members of their household from the virus”.
“Furthermore, the observed association between food allergy and the risk of infection with SARS-CoV-2, as well as between body-mass index and this risk, merit further investigation,” he added.
The findings were published in the Journal of Allergy and Clinical Immunology.