Food allergies occur when the immune system mistakenly identifies a harmless food protein as a threat, releasing chemicals like histamine that cause symptoms. This immune response distinguishes true allergies from food intolerances, which typically involve the digestive system and are less severe. Unlike fixed conditions, food allergies are not static and can change throughout an individual’s lifetime.
Allergies That Disappear
Many individuals, particularly children, can outgrow certain food allergies. Milk, egg, soy, and wheat allergies are most commonly outgrown. For example, 60% to 80% of young children with milk or egg allergies may outgrow them by age 16, and about 50% of children with soy or wheat allergies by ages seven and eight, respectively.
In contrast, allergies to peanuts, tree nuts, fish, and shellfish are less likely to resolve. Only 20% to 25% of children with peanut allergies and about 14% with tree nut allergies may outgrow them. A small percentage (4% to 5%) of children with fish or shellfish allergies will tolerate these foods later in life. This resolution involves a shift in the immune system’s response towards tolerance.
Allergies That Develop Later
New food allergies can emerge in individuals who previously tolerated those foods, including adult-onset allergies. Shellfish, tree nuts, peanuts, and fish are common allergens that can appear later in life; shellfish allergy, for example, is reported as the most common adult-onset food allergy, followed by tree nuts.
The emergence of new allergies might be linked to new exposures or alterations within the immune system. A 2019 study indicated that nearly 6% of adults in the United States acquired a new food allergy during adulthood. This highlights the dynamic nature of the immune response throughout life.
Fluctuations in Severity
Even if a food allergy does not disappear or newly develop, its severity can change over time. Reactions might become milder or more severe with subsequent exposures.
Various factors influence these shifts. The amount of allergen consumed plays a role, as larger quantities may lead to more pronounced reactions, though small amounts can still trigger severe responses.
Other influencing factors include cofactors such as physical exercise, illness, infection, stress, tiredness, alcohol consumption, and certain medications (e.g., beta-blockers or ACE inhibitors). How the food is prepared (cooked or raw) can also affect the body’s response.
Factors Influencing Allergy Changes
Changes in food allergies involve a complex interplay of genetic and environmental factors. While genetic predispositions are recognized, their precise role in developing or outgrowing allergies is still evolving.
Environmental influences, particularly early life exposures, are significant contributors. The gut microbiome’s composition and diversity, especially in early life, are impactful, playing a role in immune system maturation and oral tolerance.
Dietary factors can directly influence the gut microbiota, further affecting the immune response. The timing and type of initial allergen exposure are also important; early oral exposure to certain foods may promote tolerance, while skin exposure can sometimes lead to sensitization.
Managing Evolving Allergies
Managing evolving food allergies requires a proactive approach involving individuals and healthcare providers. Regular medical evaluations are important to monitor the allergy’s status.
Re-testing, including skin prick tests, blood tests for specific IgE antibodies, and supervised oral food challenges, helps determine if an allergy has resolved or changed in severity. Based on these evaluations, management plans, including dietary restrictions, can be adjusted.
Maintaining an emergency action plan, typically including an epinephrine auto-injector for accidental exposures, is also important. Consulting an allergist is important for accurate diagnosis, ongoing assessment, and discussing emerging treatments like oral immunotherapy, which aims to build tolerance.