by Gary Falcetano, PA, Senior Manager, Global Medical & Scientific Affairs, Allergy, Thermo Fisher Scientific
Food allergy is a dynamic condition that may begin in infancy, emerge in adulthood, or change over time. Because of this, accurate, age-appropriate testing is essential for diagnosis, risk assessment, and long-term symptom management.
Since the concept of allergy testing was first described in 1872 by English physician Charles Blackley, food allergy testing has evolved significantly. It has only become more specific, particularly with the introduction of total and specific immunoglobulin E (IgE) tests.
For laboratory professionals, this evolution has implications for test selection, workflow design, and result interpretation. Taking a lifespan-based approach to allergy diagnostics is critical and has real operational implications for laboratories.
Allergy diagnosis begins with clinical history
Food allergies are increasingly common, with prevalence rising by 50% since the 1990s, according to the U.S. Centers for Disease Control and Prevention (CDC). In parallel, allergy diagnostics have also evolved substantially.
Skin-prick testing (SPT) and specific IgE blood testing have long worked in concert in allergy diagnosis, with component-resolved diagnostics now offering enhanced specificity and improved risk stratification beyond conventional methods. Food challenge tests, also known as oral food challenges, are also extremely useful when leveraged alongside a blood test or SPT to help confirm an allergy or determine if a patient has even outgrown an allergy.
Despite these advances, the proper gathering of a patient’s clinical history is still the most important ‘test’, as serological testing and skin prick testing don’t necessarily indicate a clinical allergy, but rather sensitization to an allergen. The clinical context is necessary to accurately diagnose a clinical allergy.
Prioritizing early and accurate allergy diagnosis can help patients avoid unnecessary exposure to allergens, proactively address their symptoms, and improve their quality of life. For laboratories, this underscores the importance of analytical accuracy, reproducibility, and clear reporting.
Allergies are dynamic
Although food allergy is frequently associated with childhood, it’s actually a lifelong and evolving condition. In fact, about 10% of adults have a food allergy, while prevalence among children is about 8%. Of that adult population, almost half report onset during adulthood.
According to an article published in the Journal of the American Medical Association, adult-onset food allergies are common, severe, and an important and emerging health problem. For nearly half of food-allergic adults, at least one of their allergies began in adulthood. Moreover, a person might also develop a food allergy to something he or she has eaten for years without any problems.
For children, allergies may disappear as they age, with about 20% reported outgrowing their allergies by the time their school aged. There are several specific common allergens that they’re very likely to outgrow, including milk, soy, eggs, and wheat. On the contrary, sesame allergies persist for 80% of children, and allergy to peanuts, tree nuts, fish, and shellfish are lifelong for 80-90% of cases. These patterns highlight the need for ongoing reassessment.
The concept of the atopic march shows the progressive nature of allergic disease. The atopic march, sometimes called the allergic march, refers to the natural history or typical progression of allergic disease that often begins early in life. These include atopic dermatitis, food allergy, allergic rhinitis, and asthma.
The atopic march typically follows a specific course, where infants often initially present with eczema. An impaired skin barrier puts them at higher risk for infections and development of IgE antibodies when potentially allergenic substances in the environment can directly contact immune cells in the patient's dermis. Conversely, recent studies have demonstrated that early exposure to potential allergens through the gastrointestinal tract can substantially reduce the development of food allergy.
Early-life preventive strategies should be incorporated into routine anticipatory guidance to reduce the risk of long-term allergic disease. Clinicians should counsel families on implementing optimal skin care measures beginning in infancy, including the regular application of fragrance-free, thick emollients to support epidermal barrier function, particularly in infants at elevated risk for atopic dermatitis. Consistent moisturization, avoidance of harsh cleansers, and maintenance of skin integrity are foundational interventions.
In addition, clinicians should discuss the timely introduction of age-appropriate allergenic foods, such as peanut-containing products, beginning around 4–6 months of age (in accordance with current guidelines and individual risk assessment), as part of a comprehensive allergy prevention strategy. When there is a question of food allergy, specific IgE testing with both whole allergens and allergen components helps to confirm and rule out suspected foods and allow for more personalized management decisions.
According to national and international guidelines, the reassessment of food allergic children at regular intervals —depending on age, food and patient history, is suggested to identify possible development of spontaneous tolerance. This diagnostic data helps determine when supervised oral food challenges may be appropriate, so patients can potentially reintroduce foods to the diet and reduce unnecessary avoidance.
For laboratories, these realities reinforce the importance of lifespan-based testing strategies. Food allergy diagnostics must support both initial diagnosis and longitudinal monitoring across changing risk profiles.
Precision allergy care
One of the most significant advancements in allergy diagnostics is component-resolved diagnostics (CRD). There are two types of IgE blood testing: whole allergen and allergen component. Whereas whole allergen testing helps identify potential allergic triggers and confirm or rule out allergies, the allergen component tests focus on pinpointing specific proteins in an allergen that may be responsible for triggering symptoms.
More specifically, options like the ImmunoCAP allergen component testing measure allergic sensitization to molecules found within whole allergens, allowing for a deeper understanding of causes, risks, and management of symptoms. Knowing which specific proteins that a patient may be reacting to allows clinicians to obtain a greater understanding of the patient’s potential allergy and make a more informed diagnostic decision, when combined with the patient’s clinical history.
Some components are strongly associated with true, persistent, and potentially severe allergy, while others reflect cross-reactivity and may be associated with milder symptoms. For example, peanut storage proteins Ara h 6, along with Ara h 1, 2, and 3, are usually associated with a higher risk for systemic reactions or anaphylaxis, whereas sensitization to other components like Ara h 8, CCD, and Bet v 2, which are denatured by heat and digestion, as opposed to Ara 1, 2, 3 and 6, may indicate that patients will have either no clinical symptoms or isolated oral symptoms.
This level of diagnostic specificity allows clinicians to stratify clinical risk better, reduce unnecessary oral food challenges, and provide personalized symptom management plans. Reflex testing, when there’s a positive result from whole allergen testing that triggers further available component testing, can also streamline the diagnostic process, as it only requires only one blood draw from the patient.
As food allergy care becomes increasingly personalized, CRD will only continue to enhance diagnostic precision and clinical confidence.
Transforming the future of allergy diagnostics
Allergies are not static across patients’ lifespans; sensitization, symptoms, and risk profiles can all shift during different phases of life.
Modern food allergy care depends on integrating history, traditional specific IgE testing, and advanced allergen component diagnostics. When used together, these tools help clinicians diagnose more accurately, prevent disease progression, safely expand diets, and support patients across every stage of life.
Laboratories that recognize this dynamic nature are better positioned to support clinicians and patients along their diagnostic journey. A lifespan-based approach means aligning allergen selection, workflow design, and diagnostic technologies with the reality of how allergic disease develops and progresses across the lifespan.
About the author
Gary Falcetano, PA, is the Senior Manager of Global Medical & Scientific Affairs for Allergy in ImmunoDiagnostics at Thermo Fisher Scientific. A licensed physician assistant with more than 25 years of diverse experience in emergency and disaster medicine, primary care, and allergy and immunology.