Pollen Food Allergy Syndrome Update

Many patients who experience seasonal allergic rhinitis (i.e., hay fever) and allergic conjunctivitis (i.e., eye allergies) symptoms (e.g., sneezing, runny nose, nasal congestion, post-nasal drip, sinus congestion, itchy nose, itchy throat, sinus headaches, itchy eyes, watery eyes, redness of the eyes) caused by sensitivities to tree, grass, and weed pollens also may experience an itchy mouth and throat after eating certain fresh fruits and vegetables. As the symptoms are usually limited to the mouth and throat, this condition is known as “pollen food allergy syndrome” (PFAS). It is also known by the name “oral allergy syndrome” (OAS).

Most people with food pollen allergy syndrome have oral symptoms such as itching, burning, tingling, and occasionally swelling of the lips, mouth, tongue, and/or throat where the fresh fruit or vegetable touches the mouth. This represents a form of contact urticaria, since there is direct contact of the food to the mouth region. The symptoms usually only last a matter of seconds to a few minutes. The symptoms are also more likely to occur in the season that the cross-reactive pollens are also prevalent.

The oral symptoms occur only when a pollen-allergic individual is exposed to raw or fresh vegetables, fruits, and/or nuts. Food pollen allergy syndrome typically does not occur with cooked or baked fruits, vegetables, or processed fruits such as in applesauce as the cooking process inactivates or denatures the protein allergens in the foods. The exception to this rule is with celery and nuts where the oral allergy symptoms typically occur even if they have been cooked.

The cause for food pollen allergy syndrome is thought to be a cross-reactivity between the protein allergens in the pollen and the fresh fruits and/or vegetables. Fruit and vegetable proteins (i.e., allergens) share varying degrees of structural similarities with allergens found in pollens as well as other fruits and vegetables. This structural homology confuses the immune system and causes an allergic reaction to occur. The patient’s body “sees” the fruit or vegetable protein allergen as the pollen allergen and reacts to the food because it “thinks” it is the pollen. This homology or similarity between the food allergen and the pollen allergen is referred to as cross-reactivity.

Certain pollens are more likely to be cross-reactive with certain fruits, vegetables, and/or nuts. Below is a list of the cross-reactivity that may occur between common pollens and common raw or fresh fruits, vegetables, and/or nuts:

  • Alder pollen: almonds, apples, celery, cherries, hazelnuts, peaches, pears, parsley
  • Birch pollen: almonds, apples, apricots, avocados, bananas, carrots, celery, cherries, chicory, coriander, fennel, fig, hazelnuts, kiwi, nectarines, parsley, parsnips, peaches, pears, peppers, plums, potatoes, prunes, soy, strawberries, wheat, peanuts
  • Grass pollen: fig, melons, tomatoes, oranges
  • Mugwort pollen (i.e., celery-mugwort-spice-syndrome): carrots, celery, coriander, peppers, fennel, parsley, sunflower
  • Ragweed pollen: banana, cantaloupe, honeydew, watermelon, cucumber, zucchini, Echinacea, artichoke, dandelions, hibiscus tea, chamomile tea

Note: Any of the above pollens may cross-react with berries (e.g., strawberries, blueberries, raspberries), citrus (e.g., oranges, lemons), grapes, mango, fig, peanut, pineapple, pomegranates, and/or watermelon.

When a fruit or vegetable allergy develops in the absence of a pollen allergy, patients may be sensitized to nonspecific lipid transfer proteins (nsLTPs) or to gibberellin-regulated proteins (GRPs). In general, sensitization to these proteins is associated with higher rates of systemic reactions as well as higher rates of food-dependent, exercise-induced anaphylaxis. The allergens responsible for isolated food allergy are typically resistant to both heat and digestion and therefore have a greater potential to cause systemic symptoms.

There are also several syndromes that are associated with pollens and foods:

  • Celery-mugwort-birch-spice syndrome — The celery-mugwort-birch-spice syndrome is a potentially severe form of celery allergy seen in children and adults who are sensitized to both birch and mugwort pollens. Patients with this syndrome react to celeriac (i.e., root of the celery plant or celery tuber).
  • Mugwort-pollen food allergy syndrome — Patients sensitized to mugwort (Artemisia vulgaris) may develop a systemic food allergy (e.g., to mustard).
  • Latex-fruit syndrome — Approximately 30-50% of individuals who are allergic to natural rubber latex show an associated hypersensitivity to some plant-derived foods, especially fresh fruits. An increasing number of plant foods, such as avocado, banana, bell pepper, chestnut, kiwi, peach, tomato, and white potato, have been associated with this syndrome.

Diagnosis: The diagnosis is suspected when a comprehensive history is suggestive of pollen food allergy syndrome. Allergy tests such as prick skin testing, food elimination, and oral food challenges are helpful in establishing the diagnosis. Food prick skin testing with fresh foods is more reliable than commercial extract food prick skin testing because the process of making the extract can destroy the responsible protein allergen.

Treatment: The treatment of pollen food allergy syndrome involves avoiding exposure to the involved fresh or raw fruits, vegetables, and/or nuts to prevent the uncomfortable feeling in the mouth and throat, as well in order to reduce the risk of rare systemic symptoms. Taking antihistamines can minimize the severity of the symptoms however systemic reactions need treatment with epinephrine injections. Patients with a history of a systemic reaction should be prescribed a self-injectable epinephrine device (e.g., EpiPen, Auvi-Q, Adrenaclick) and instructed on when and how to use it. It is important that the patient go immediately to the closest emergency room once a self-injectable epinephrine device is used.

Some studies have demonstrated that treating pollen allergies with allergy immunotherapy (i.e., allergy shots, allergy injections, allergy hyposensitization) can reduce the symptoms associated with cross-reacting fruits and vegetables that cause pollen food allergy syndrome.

The board certified allergy doctors at Black & Kletz Allergy will eagerly respond to your needs for further information and services in dealing with food allergies, pollen food allergy syndrome, and other allergic and immunologic disorders.  The allergists at Black & Kletz Allergy have 3 convenient locations in the Washington, DC, Northern Virginia, and Maryland metropolitan area.  Our offices are located in Washington, DC, McLean, VA (Tysons Corner, VA), and Manassas, VA.  We offer on-site parking at all of our offices and our Washington, DC and McLean, VA offices are Metro accessible. There is a free shuttle that runs between our McLean, VA office and the Spring Hill metro station on the silver line.  To make an appointment, please call our office or alternatively, you can click Request an Appointment and we will respond to your inquiry within 24 hours by the next business day.  Black & Kletz Allergy treats both adults and children and we strive to provide the best and most current diagnostic and treatment modalities in the Washington, DC metro area, as we have done for more than 5 decades.