Understanding adult-onset food allergies

When you think of food allergies, you may picture common childhood allergies such as peanuts and shellfish. But did you know adults can develop food allergies as well? A recent study has shown that roughly 10% of adults in the U.S. have food allergies, and half of them developed those allergies later in life.

Dr. Ashika Odhav, an allergist and immunologist with Sharp Rees-Stealy Medical Group, cautions that the results of this particular study do not reflect the overall trend. While food allergies in children are increasing, adult-onset cases are not. However, she explains how these allergies develop in adults and what to do if you think you may have one.

What causes food allergies to develop later in life?
Food allergies occur when your body perceives a food as harmful and releases an antibody called immunoglobulin E (IgE). According to Dr. Odhav, adult-onset allergies can occur if you were never introduced to common food allergens in childhood. Childhood allergies can also continue into adulthood.

While family history can play a role in some types of food reactions, such as lactose intolerance and celiac disease, it does not have an effect on adult-onset allergies.

What are the most common types of food allergies in adults?
The most common types of allergies that arise in adults are peanuts, tree nuts, fish and shellfish. Adults can also develop food intolerances as they age.

“A food intolerance, such as lactose intolerance, does not cause an immune reaction and it typically involves the gastrointestinal (GI) tract, causing uncomfortable symptoms like abdominal pain, nausea, vomiting and diarrhea,” Dr. Odhav says. Treatment involves avoiding the food, or for lactose intolerance, taking supplements.

What are the typical symptoms of an allergic reaction triggered by food?
“When food allergens cause your body to produce IgE, those antibodies attach to cells in your skin, lungs and gastrointestinal (GI) tract,” Dr. Odhav says. “If you come in contact with the allergen again, the cells release chemicals including histamine, which cause food allergy symptoms such as itching, hives, swelling, diarrhea, wheezing and a potentially life-threatening reaction called anaphylaxis.”

Symptoms of anaphylaxis may include difficulty breathing, dizziness or loss of consciousness. If you have any of these symptoms after eating, use an epinephrine auto-injector (EpiPen) and immediately call 911. Don’t wait to see if your symptoms go away or get better on their own.

What should you do if you think you have a food allergy?
“If you have questions regarding a reaction that may or may not be related to a food, you should speak with your primary care doctor first. They may refer you to an allergist and immunologist, who has specialized training and expertise to determine if your symptoms are caused by a food allergy or due to other food-related disorders,” Dr. Odhav says.

When you meet with an allergist, they will look through your medical history and conduct a physical examination. You will be asked about the foods you eat; the frequency, severity and nature of your symptoms; and the amount of time between eating a food and any reaction. If the history is suspicious for an IgE-mediated food allergy, then allergy skin or blood tests may determine which foods, if any, trigger your allergic symptoms.

What advice do you have for an adult who develops a food allergy?
“Avoidance, education and preparedness are the keys to managing a food allergy,” Dr. Odhav says. “Eating even a small amount of the food, such as crumbs left on utensils, can cause a life-threatening reaction. That’s why reading the ingredients on food labels and asking questions about prepared foods are an essential part of avoidance plans.”

People with a food allergy should always carry an epinephrine auto-injector to be used in the event of an anaphylactic reaction. If you have questions about your allergies and their severity, consult with your primary care doctor.