A friend tells me she was recently tested for allergies. “I tested positive to birch, walnut, and olive trees … and peanuts, but no other foods. With the birch allergy, I was also diagnosed with Oral Allergy Syndrome (or Pollen Allergy Syndrome). Do you know anything about it?”
I know more about it thanks to a recent review of this topic in the Journal of the Academy of Nutrition and Dietetics. Food allergies are well defined, reports registered dietitian Jill Balla Kohn. Oral Allergy Syndrome (OAS) is not.
A food allergy, according to experts at the National Institute of Allergy and Infectious Diseases, is an immune response after a repeated exposure to substances in food — typically proteins — that causes an adverse effect on health.
Oral allergy syndrome (OAS) is a collection of symptoms related to a reaction to proteins in pollen — the male part of a seed plant that “pollinates” other plants. That’s why OAS is sometimes called “pollen-food allergy.”
As might be expected, people with hay fever or other pollen allergies are more susceptible to oral allergy syndrome. That’s because some proteins in pollen are similar to proteins in certain foods. So a person who is allergic to grass, for example, may also be sensitive to foods with related proteins such melons, oranges or tomatoes.
Food allergies and OAS usually have different symptoms, however. Food allergies can affect every part of the body and cause breathing, hives on the skin or stomach problems. OAS symptoms are usually limited to areas around the mouth and throat. (My daughter’s lips get itchy when she eats cantaloupe, for example.)
The good news, says Kohn, is that many people who are sensitive to pollen never develop sensitivities to related foods. And people with oral allergy syndrome can often eat cooked versions of their offending foods since many of the proteins associated with pollen are destroyed by heat.
Some (many) people have food allergies as well as oral allergy syndrome which makes life really interesting. According to the Food Allergy Research and Resource Program, www.farrp.unl.edu, 90 percent of allergic reactions to food are caused by peanuts, milk, eggs, wheat, soy, tree nuts (i.e. almonds, walnuts, pecans), fish, and crustacean shellfish.
Once a food allergy is identified, the tried and true treatment is to avoid it. And in the case of a true food allergy, all forms of the offending food, including cooked, should be avoided.
“Should I ask to see a dietitian or just follow the diet and experiment as I go?” my friend asks.
Yes and yes. Once the diagnosis of food allergy or OAS is made, a nutrition professional can help you identify closely-related foods that may be causing symptoms.
(Barbara Quinn is a registered dietitian and certified diabetes educator affiliated with Community Hospital of the Monterey Peninsula. She is the author of “Quinn-Essential Nutrition” (Westbow Press, 2015). Email her at to firstname.lastname@example.org.)