Food allergies are dominating headlines, altering nutrition labels and changing the way products get marketed in the United States. Although not as common as in children, food allergies can affect adults.
According to a recent study in the Journal of the American Medical Association (JAMA), an estimated 26 million U.S. adults, or 10.8 percent of the adult population, have a food allergy. Although only 5 percent of adults have physician-diagnosed food allergies, up to 19 percent of adults believe they are allergic to certain foods.
Food allergies can be dangerous, no matter what the age, so it’s important to understand when a reaction to a certain food should be cause for concern, said Saffana Hassan, MD, an allergist affiliated with Memorial Hermann Greater Heights Hospital.
“Adults can develop an allergic reaction at any point in their life,” Dr. Hassan said. “Those who suspect they have a food allergy should definitely consult a medical professional because we’ve seen that even after minor reactions, the next reaction can be fatal.”
What is a food allergy?
A food allergy is the immune system’s overreaction to a food protein. There are many symptoms of an allergic reaction to food, ranging from mild to severe and even fatal.
Mild and moderate allergic reactions to food include: hives; redness in the face, especially around the mouth and eyes; itchiness in the mouth or ear; sneezing; coughing; unfamiliar tastes; congestion or runny nose; nausea, and at times, vomiting and diarrhea.
“Whenever we see even a mild reaction to a food and people test positive for antibodies to that food, we usually tell the patient to stay away and we prescribe an epinephrine pen for them to carry with them,” Dr. Hassan said. “There is no guarantee that even if you accidentally consume that food again that your reaction will also be mild.”
When should I seek medical care?
People should immediately seek professional medical help when they experience a severe allergic reaction to food. A severe allergic reaction is called anaphylaxis and its onset can be sudden and send the body into shock.
Severe allergic reactions to food include: tightening of the throat; swelling of the tongue; trouble breathing or swallowing; chest pain; feeling faint or dizzy; unconsciousness; a drop in blood pressure and turning blue. Some reactions can be fatal.
How do I know I have a food allergy?
It can be difficult to determine which food may be triggering an allergic reaction because symptoms can present within minutes or hours after consumption.
“In general, if you can establish a linear relationship between eating a certain food and symptoms of a food allergy, then there is a good chance a food allergy exists,” Dr. Hassan said.
What tests are there for food allergies?
The most accurate way to determine a food allergy is through allergy testing conducted by a healthcare professional.
The most common food allergy test is the relatively painless “scratch” or skin prick test (SPT), where proteins from the suspected allergen are placed on a small area of skin for about 20 minutes. The skin is pricked or scratched but never broken during the test, which measures the presence of immunoglobulin E (IgE) antibodies reacting with the food.
If the scratch test is positive, then blood is drawn and tested to determine the IgE antibody levels.
Other tests include the food elimination diet and the oral food challenge, the latter of which should only be done under the supervision of an experienced allergist because of the risk of severe allergic reaction.
What are the most common foods that cause allergies?
An estimated 90 percent of food allergies are caused by eggs, milk, peanuts, tree nuts, fish, shellfish, wheat or soy, according to the American College of Allergy, Asthma and Immunology (ACAAI).
“A lot of adults say they are allergic to milk, but they may actually have lactose intolerance,” Dr. Hassan said.
Milk allergies certainly exist but they are not the same as lactose intolerance. A milk allergy is an immune system reaction to a protein in milk. People who are lactose intolerant typically do not have a specific enzyme that allows them to digest milk.
What about food allergies among children?
According to the ACAAI, up to 6 million children have food allergies, the most common being egg, milk, wheat and nuts. Symptoms of food allergies are similar among adults and children.
“A lot of children outgrow their allergies by age 6 or 7,” Dr. Hassan said. “The exception is peanut allergies, which a majority of children do not outgrow.”
Food allergy tests are the same for children and adults.