About 1 in 25 adults in the United States has a food allergy. (The proportion in children is slightly greater because some will outgrow their symptoms).1 Food allergies have become more common in recent years, yet the reasons for this change are not clear.2
The immune system defends the body against disease. In individuals with food allergies, it attacks components of particular foods, such as peanuts or shellfish, as though they present a threat. An allergen – a substance that triggers this response – may cause a mild reaction, such as itchiness, or harsh one, such as digestive distress. These reactions harm the body like friendly fire from the immune system. A severe response called anaphylaxis can be life threatening. Symptoms include dizziness and difficulty breathing. An injection of epinephrine, followed by a visit to the emergency room, can treat anaphylaxis.3
Allergies are a public health concern that can cause sickness and even death. Diagnosing and treating them requires patients, providers, and institutions to spend time and money.
One proposed explanation of the increase in food allergies is the hygiene hypothesis. "People who live in more sanitary environments, who have less infections, less exposure to livestock and farming, are more likely to develop" a range of immune diseases, including allergies and asthma, says Doug Brugge, PhD, Professor of Public Health and Community Medicine. This difference is reflected in higher rates of immune disorders in industrialized countries, a pattern Brugge and colleagues saw when comparing asthma rates between individuals in Boston's Chinatown born in the U.S. and those born abroad.
While the hypothesis is supported by "very compelling evidence," says Brugge, "we don't understand the exact details." Other factors might contribute to allergies in addition to or instead of sanitation. For example, inadequate vitamin D levels may contribute to allergy development, possibly because of vitamin D's role in the immune system. For years, parents were urged to shield young children from potential allergens. However, early exposure to these foods may acclimate the body and reduce the risk of allergies.
Many institutions, ranging from restaurants to airlines to colleges, are adapting to rising rates of food allergies.4 "I have seen a huge increase [in severe allergies] over the last decade," says Julie Lampe, RD, Nutrition Marketing Specialist at Tufts University. "We have all our ingredients and allergens listed on food fact cards, which are at the point of service." Tufts Dining Services also trains new staff to avoid contaminating allergen-free food with ingredients from other dishes and to direct questions to an appropriate supervisor. A well-intentioned but incorrect answer, reassuring someone that the allergen is not present, can lead to a dangerous allergic reaction.
Dr. John Leung, Director of the Food Allergy Center at Tufts Medical Center, Co-Director of the Food Allergy Center at Floating Hospital for Children, Allergist, and Assistant Professor at Tufts University School of Medicine, has another concern: misdiagnosis. In his practice, for example, he saw a young boy who was incorrectly diagnosed with an egg allergy. "In daycare, at three years old, he had to stand aside because he couldn't eat birthday cake," says Dr. Leung. "He became very socially isolated."
Dr. Leung worries about the impact of misdiagnosis, which can lead to needless dietary restrictions and even nutritional deficits. He notes that this issue disproportionately affects families who cannot access quality healthcare or cannot afford to take time off from work for an appointment.
More research is needed to understand the causes of food allergies. In the future, perhaps a pill or vaccine will prevent allergies. For now, health professionals work to raise awareness to protect those with allergies without provoking unwarranted anxiety or isolation.
For more information about allergies, visit the National Institute of Allergy and Infectious Diseases. Learn more about food allergies at Tufts.
1. Diseases, N.I.o.A.a.I. Food Allergy. [cited 2016; Available from: https://www.niaid.nih.gov/diseases-conditions/food-allergy
2. Kattan, J., The Prevalence and Natural History of Food Allergy. Curr Allergy Asthma Rep, 2016. 16(7): p. 47.
3. Plus, M. Food Allergy. [cited 2016; Available from: https://medlineplus.gov/foodallergy.html
4. Jones, S.M. and A.W. Burks, The changing CARE for patients with food allergy. J Allergy Clin Immunol, 2013. 131(1): p. 3-11; quiz 12-3.