Food Allergy is a growing concern, especially when it is a child who is affected. The prevalence is highest in the first two years of life. The prevalence falls progressively with time to an average of three percent of the total population. Food allergies can occur in adults, but it is much less common than in children. Up to one-third of parents will report an adverse reaction to foods that are not true allergies. These can include a rash around the mouth from strawberries, tomato products, and citrus, as well as lactose or milk intolerance.
A food allergy results when the immune system mistakenly targets a harmless food protein—an allergen—as a threat and attacks it. Unlike other types of food disorders, such as intolerances, food allergies are “IgE mediated.” This means that your immune system produces abnormally large amounts of an antibody called immunoglobulin E—IgE for short. IgE antibodies fight the “enemy” food allergens by releasing histamine and other chemicals, which trigger the symptoms of an allergic reaction. Reactions to foods can vary. Symptoms include
Although nearly any food can cause an allergic reaction, eight foods account for 90% of all food-allergic reactions in the United States. These foods are: Peanut, Tree nut, Milk, Egg, Wheat, Soy, Fish and Shellfish.
In children, the most common food allergens are milk, egg, wheat, soy, peanuts, and tree nuts. Adults who develop food allergies are more likely to be allergic to peanut, tree nut and seafood, especially shrimp; however, children can also develop allergies to shellfish and fish.
The good news for most children with milk and egg allergy is that 70–80% of them will outgrow these allergies with time. Recent studies suggest that on average, half of children with milk and egg allergy will become tolerant by age 8-12 years old. The news is not as good for peanut allergy. Only 25% (usually infants who develop peanut allergy) will become tolerant with time. Very few adults who develop allergy to tree nuts, peanuts or seafood become tolerant.
Food allergy is often an early indicator that other allergies may follow. Children with food allergy, especially to eggs, have a 50-90% of developing allergies and asthma, as they get older. Of milk allergic children, 50% will have an allergy to other foods and 40% of children with peanut allergy will develop allergy to other nuts. One-third of children with severe atopic dermatitis (eczema) will have a food allergy trigger.
The food that caused the reaction may not be obvious. Our board-certified allergy specialist often use more than one type of test to diagnose food allergy. Allergy skin prick testing, ImmunoCap (blood tests), and when appropriate, oral food allergy challenges are utilized to confirm a diagnosis. Additionally, we are now able to conduct component testing for peanut allergic patients to determine the risk of having a severe reaction.
Allergy skin testing is the most accurate and preferred method of evaluating allergies. These tests are safe, minimally invasive, and easily interpreted. Blood assays or ImmunoCap may present the clinician with diagnostic challenges. Studies have shown variability between different labs so that results can be difficult to interpret. Blood tests also have decreased sensitivity compared to skin testing. Results from blood tests can often take a week or longer to be reported.
There are times when an oral food challenge is performed to confirm a specific food allergy diagnosis. This should be done in a medical facility by a board-certified allergy specialist who is specially trained in this procedure.
The most important aspect of treatment for food allergy is an accurate diagnosis.
Unfortunately, there is no cure for food allergy at this time. Strict avoidance of the allergy-causing food is the ONLY way to prevent a reaction. Every patient should read labels on packaged foods and ask friends and family what ingredients they have used. Do not eat foods from a buffet that you cannot identify and do not be shy in restaurants.
Always make the chef aware of your specific allergies. Always be prepared for accidental ingestion by carrying self-injectable epinephrine. Do not leave home without an epinephrine auto-injector! There are several forms of auto-injectable epinephrine: Epi-Pen, AuviQ, and generic epinephrine (formally Adrenaclick). Make sure you and those close to you are trained and comfortable with how to use the one you have. If the epinephrine is used, proceed to the nearest ER for observation. The benefits of epinephrine may only last 15–20 minutes, which means the reaction can reappear. Use this time to call 911 and go directly to the ER for evaluation and additional treatment.