In addition to studying common food allergies, such as peanut, milk and egg allergies, NIAID funds research on disorders that are related to, or occur alongside, food allergy. Research related to these increasingly diagnosed conditions may offer insight on treatment and prevention.
Oral Allergy Syndrome
Oral allergy syndrome is an allergic reaction to certain raw fruits and vegetables, such as apples, cherries, kiwis, celery, tomatoes, melons, and bananas. Oral allergy syndrome occurs in people with hay fever, or cold-like symptoms caused by allergies. The syndrome is most likely to occur in those allergic to birch, grass and ragweed pollens because some of the protein allergens in these types of pollen are similar in structure to the proteins of certain fruits.
Those with oral allergy syndrome generally do not experience life-threatening reactions, but they can experience a rash, itching, swelling and sneezing if they eat or even just hold these raw fruits and vegetables. Similar to the experimental baked food approach to treating other food allergies, symptoms typically do not occur after consuming cooked or baked fruits and vegetables, as cooking or processing fruits and vegetables easily breaks down the proteins that cause oral allergy syndrome.
Eosinophilic esophagitis, or EoE, is a chronic disease that can be associated with food allergies. It is increasingly being diagnosed in children and adults. EoE is characterized by immune cells called eosinophils building up in the esophagus.
Symptoms of EoE include nausea, vomiting, and abdominal pain after eating. A person may also have symptoms that resemble acid reflux from the stomach, known as heartburn. In older children and adults, EoE can cause more severe symptoms, such as difficulty swallowing solid food, or solid food getting stuck in the esophagus and requiring removal by a physician. In infants, this disease may be associated with failure to thrive.
NIAID-funded researchers have found several genes associated with the development of EoE and have evaluated treatment with swallowed anti-inflammatory drugs called corticosteroids. A person diagnosed with EoE is usually tested for food allergies. Oftentimes, those that have both food allergy and EoE can avoid EoE symptoms by avoiding their allergen. NIAID currently funds studies investigating the effectiveness of food avoidance diets and other, experimental approaches to controlling EoE.
Conditions Often Mistaken for Food Allergy
People can feel ill after eating specific foods for reasons other than food allergy. Though these disorders may have some symptoms in common, these illnesses should not be confused with food allergy.
A problem often confused with food allergy is food intolerance, which is also an abnormal response to a food product, but differs from an allergy. A common example is an intolerance to lactose, a sugar found in many milk products that can cause an uncomfortable buildup of gas in the gastrointestinal tract. Gluten intolerance, or celiac disease, occurs when the immune system responds abnormally to gluten, a component of barley, wheat, and rye. However, unlike food allergies, these disorders do not involve IgE antibodies. The National Institute of Diabetes and Digestive and Kidney Disorders (NIDDK) currently conducts research on lactose and gluten intolerance. Visit the NIDDK website for more information.
Foodborne illness, or food poisoning, can also be confused with food allergy because of similar symptoms, such as abdominal cramping. Foodborne illness, however, is caused by microbes, microbial products, and other toxins that can contaminate foods that were improperly preserved or processed.