A food allergy is now a common condition and affects 1-2% of adults and 4-8% of children under five years old. Data from The Journal of Allergy and Clinical Immunology also indicates that 10% of children under the age of one have a proven food allergy.
Food allergies usually appear in the first years of life and manifest in itchy rashes and facial swellings that occur shortly after food ingestion. Less common symptoms of food allergy include infantile colic and failure to thrive, reflux of stomach contents, eczema and chronic diarrhoea. Food allergies can also cause severe allergic reactions involving breathing difficulties, vomiting or diarrhoea and are the most frequent triggers of anaphylaxis in children.
The Australasian Society of Clinical Immunology and Allergy (ASCIA) has reported hospital admissions for severe allergic reactions (anaphylaxis) have doubled over the last decade in Australia, the US and the UK.
It’s still uncertain as to why a growing number of children are allergic to everyday foods, such as peanuts, eggs, tree nuts, sesame, dairy, fish, crustaceans and soy. However, current research suggests that the causes of food allergies involve a complex interplay of genetics and environment. In 2017, the world’s largest study into the genetic causes of food allergies discovered a total of five genetic risk loci for food allergies. “Studies of twins suggest about 80% of the risk for food allergies is heritable, but little is known so far about these genetic risk factors,” says Professor Young-Ae Lee, a researcher at Max Delbrück Center for Molecular Medicine in Germany.
According to ASCIA, proposed explanations for the rise in allergies (not yet proven in studies) include hygiene hypothesis, which proposes that less exposure to infections in early childhood is associated with an increased risk of allergy; delayed introduction of allergenic foods; methods of food processing, such as roasted versus boiled peanuts; and development of allergy to food by skin exposure, such as the use of unrefined nut oil-based moisturisers.