Just because your mother is allergic to strawberries doesn’t mean that you are allergic to strawberries. And just because you’ve gotten a headache after eating shrimp doesn’t mean you’re allergic to that food either.

Enter the interesting world of food allergies, a place where researchers don’t really know how a person develops a specific allergy, a place often misunderstood by the public. It’s a world that Dr. Alan DeJarnatt, who specializes in treating asthma and allergies, works in daily.

“There are different ways that foods can cause symptoms,” said Dr. DeJarnatt, who practices at Allergy and Asthma Care. “It’s important to know that only a small percentage are actually food allergies.”

If, for example, you don’t feel well after eating a certain food, you have a non-specific intolerance to the food. That’s not a food allergy, he says. A lactose intolerance occurs in some people because they’re not making the enzyme that breaks down the milk’s sugar. Again, that intolerance is not an allergy to milk products.

Specifically, a true food allergy involves the production of allergic antibodies directed against specific food allergens. When people who make those antibodies eat a certain food, they develop symptoms when the antibodies and the allergens meet. Some symptoms are gastrointestinal, such as nausea, diarrhea and vomiting. Some people develop skin rashes. Some people have systemic reactions to the food involving both the skin and gastrointestinal system.

“Rarely, though,” he said, “do food allergies cause only respiratory symptoms, such as trouble breathing.”

Some allergies cause serious reactions, such as throat swelling, vomiting and system-wide reactions. A small percentage of people can have a severe enough reaction that they could die.

How we develop a food allergy is a mystery, he said. “You have to have the genetic ability to make allergic antibodies. For an unknown reason, the immune system becomes primed against a food that causes us to make antibodies to that specific food.”

Other food allergy facts
  • Food allergies are becoming more common; researchers are trying to find out why.
  • You can develop a food allergy at any age. A child begins making allergic antibodies at about six months.
  • The most common allergies in young children are cow’s milk, eggs, soy and peanut butter.
  • Adults are more likely to be allergic to shrimp or crustaceans, tree nuts (like pecans and walnuts), peanuts and fish.
  • People often grow out of their allergies, said Dr. DeJarnatt. “Most children with a milk allergy can drink milk by preschool.” However, people with an allergy to peanuts or shrimp have a low likelihood of losing their reaction to the food over their lifetime.
  • If your parent or a sibling has a specific food allergy, you are more likely to get a food allergy, but not necessarily to the same food.
  • Skin testing is the most sensitive and specific method to detect allergic antibodies to a food. Some blood tests also are helpful.
  • Researchers haven’t found a way to prevent a food allergy or to desensitize you to the food so that you can eat it without an allergic reaction.
Treating food allergies

The first step in treating a food allergy is to simply avoid the food. “If a symptom occurs with some consistency, obviously the worst thing to do is to continually expose yourself to the food,” said Dr. DeJarnatt.

If the reaction to the food is slight, an antihistamine will lessen the effect. Other people, who have more severe reactions to certain foods, keep epinephrine with them to give themselves an emergency auto injection in the thigh if they are inadvertently exposed to the food. Then they head to an emergency room.

If you think you have a food allergy, see your physician to get tested so that you know for sure.

“It’s unfortunate if someone has manipulated his or her lifestyle and diet and not really have an allergy to the food,” said Dr. DeJarnatt. “They’ve made a false connection. That’s a reason to be evaluated.”

So, don’t deny yourself the sweet taste of strawberries unless you are sure.

Featured Doctor

Alan DeJarnatt, M.D. Allergy and Asthma

Dr. DeJarnatt received his medical degree from the University of Tennessee Center for the Health Sciences in Memphis. He completed his residency in internal medicine at Texas A&M University and Scott & White Hospital in Temple, Texas, before completing a fellowship in allergy and immunology at the University of Texas Medical Branch in Galveston.

He has been practicing medicine in Jackson since 1992.
He is board certified in internal medicine and in allergy and immunology. He is a member of the American Academy of Allergy, Asthma and Immunology; the American College of Allergy, Asthma and Immunology; the West Tennessee Consolidated Medical Assembly; and the Tennessee Medical Association.