The number of people with food allergies in the UK has more than doubled since 2008, with the biggest increase occurring in young children.

In a new analysis, researchers from Imperial College London estimate that the number of people with food allergies in England increased significantly between 2008 and 2018. The analysis found that up to 4% of preschool children have a food allergy, while the rate for adults is around 1%. These rates are likely to be representative of the UK

The analysis, published in The Lancet – Public Healthalso found that many people who had previously had a severe reaction due to a food allergy (anaphylaxis) were not prescribed life-saving adrenaline auto-injection pens.

The researchers emphasize that the number of newly diagnosed cases of food allergies may be declining in some age groups. However, it is unclear whether this is due to changes in infant feeding guidelines.

However, most patients with food allergy, including those with a previous history of anaphylaxis, are treated only in primary care: only about 10% were examined by a hospital specialist at least once during the 10-year study period.

According to the authors, there is an urgent need to ensure that general practitioners and other primary care staff are adequately trained and supported to care for people at risk of severe food allergy.

Dr Paul Turner, Professor of Paediatric Allergy at the National Heart & Lung Institute, Imperial College London, who led the study, said: “This new analysis paints an important, if mixed, picture of food allergy in the UK.

“The good news is that while the number of new cases each year has increased, the prevalence of food allergies has remained stagnant. However, more than a third of patients at risk of severe reactions do not carry potentially life-saving epinephrine auto-injectors such as EpiPens.

“We need to address this urgently and better support GPs and healthcare professionals who care for the vast majority of food allergy patients in the UK.”

A food allergy occurs when the immune system overreacts to certain foods, such as cow’s milk, peanuts, eggs, or shellfish. In severe cases, anaphylaxis can occur, which, if not treated immediately, can cause swelling of the airways, difficulty breathing, and cardiac arrest.

In the latest study, researchers estimated trends in the clinical incidence and prevalence of food allergy in the UK population. Using anonymised data from GP practices covering 13 million patients, the team searched for cases of food allergy between 2008 and 2018 and linked the data to relevant contacts at GPs and hospitals in England.

The analysis found that the overall estimated prevalence of food allergy in the UK increased from 0.4% to 1.1% between 2008 and 2018. In 2018, prevalence was highest in children under 5 years of age (4%), lower in school-age children (2.4% in children aged 5-9 and 1.7% in 15-19 year-olds), and lowest in adults (0.7%).

The estimated number of new cases of probable food allergy in the UK doubled between 2008 and 2018, from 76 cases per 100,000 people in 2008 to 160 cases per 100,000 people in 2018.

More than 97% of visits for food allergies occurred in a general practitioner’s office rather than in a hospital, and approximately 90% of patients had only primary care visits throughout the 10-year study period.

Prescription of adrenaline auto-injectors to patients with previous anaphylaxis was estimated at 64% in children and adolescents and only 55% in adults. Prescriptions were also less common for people in poorer regions of the country.

According to the researchers, their study is the first to use a large, population-based health dataset to describe how the picture of food allergies has changed in the UK.

They suggest that while more doctors have diagnosed food allergies over the past decade, the number of new cases may have declined due to changes in infant feeding guidelines that no longer recommend delaying the introduction of foods such as peanuts into infants’ diets.

For children with a higher risk of food allergy (e.g. with infant eczema), it is now standard practice to introduce eggs and peanuts earlier.

Professor Adnan Custovic, of the National Heart & Lung Institute at Imperial College London, said: “A worrying finding from our study is the suggestion that patients in poorer areas of the country may not have access to the vital medicines they need and are therefore more likely to attend hospital emergency departments. This urgently needs to be investigated further.”

Professor Jenny Quint, from the School of Public Health at Imperial College London, said: “Our work shows that using large health data sets can help us cut through the noise and identify changing trends in allergies in the UK and ultimately determine whether interventions are working.”

Earlier this year, Professors Turner and Custovic founded the Frankland-Kay Centre for Allergic Diseases at Imperial College London. The centre is dedicated to advancing allergy research and reducing the impact of allergies on sufferers and their families.

Dr Turner added: “Food allergies can have a huge impact on people’s lives and, in some tragic cases, can even end their lives prematurely. By better understanding the prevalence of food allergies in the UK and working with sufferers, their families, scientists and doctors, we can work together to reduce this impact.”