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Oral allergy syndrome (OAS) is a widely recognized but little known condition. It is characterized by a burning sensation or mouth pain and swelling when you eat specific foods that cross-react to pollens you are allergic to. Interestingly, the specific foods that cause this reaction are well established to cross-react with certain trees, grass or weed pollens, dust mites, or latex. There are common groups of foods that cluster with certain nasal allergies. For example, ragweed allergy often causes an oral or intestinal reaction after eating melons or bananas, but usually no other food. Birch tree pollen is commonly associated with reactions to numerous foods, as well as latex allergies. The explanation for these reactions include similarities in protein structures and some of the chemicals in the food.
While this reaction is well documented in the allergy literature, it is not widely recognized or diagnosed by most physicians, including some allergy specialists and many stomach specialists. Several allergy websites have lists of common foods associated with certain pollens, dust mites, or latex. However, a comprehensive list that is easy to read or interpret can be difficult to find. Also, the names of some pollens or the common connections between a group of pollens and a group of foods can be confusing.
In its classic form, OAS should be easy to spot. After eating a food associated with pollen that you are allergic to, you almost immediately experience a burning sensation in your mouth or throat with or without swelling. However, it is widely recognized that in medicine, symptoms often do not appear in the “classical” or typical way in a specific person. Phrased another way, doctors are taught “patients don’t read the textbooks.” Therefore, you may experience variations of the reaction, such as swelling or tightness of the throat, burning sensation when swallowing, a lump in the throat, or a feeling of difficulty swallowing, but not related to what you ate or what happened to you.
You or your doctor may misinterpret your symptoms. Often people just assume it happened because they choked on food that was badly chewed, swallowed too quickly, or eaten or drunk while it was too hot or too cold. Usually, an esophageal (swallowing) disorder, especially acid reflux with a hiatal hernia, is believed to be the cause. Acid reflux can cause a narrowing of the esophagus called a stricture or ring that can result in a feeling of food plaque, but this is usually associated with heartburn symptoms or food getting stuck, which then gives rise to an upper endoscopy or scope examination. Other times, especially if it occurs in an older person, it is blamed on a neurological condition such as a stroke or Parkinson’s disease. Sometimes doctors decide that your symptoms are due to a nervous reaction or neurosis that used to be called globus hystericus. The hysteric part of the term is nowadays usually dropped to the shorter term globus or globus sensation, mainly because it has not been proven to be due to a psychiatric problem. However, Globus may be the diagnosis made if your complaint is that you feel a lump in your throat and an ‘evaluation’ seems to be futile, even if OAS was not considered or ruled out.
An uncommon condition more recently recognized in the field of gastroenterology (diseases of the stomach and intestines) that may be related to or a variant of OAS is called eosinophilic esophagitis (EE) or allergic esophagitis. It was first described in pediatric patients, but is now known to occur in adults. Classically described in teenage boys and young men who presented with food plaque episodes without symptoms of heartburn or acid reflux, it is associated with a strange appearance of the esophagus on endoscopy (illuminated scope examination of the upper gastrointestinal tract). What the doctor doing the scope sees is that the esophagus looks like a cat’s esophagus. That is, it looks like it has rings (cats have cartilage rings in their esophagus, we don’t) and this is called “ringed esophagus” or felinization of the esophagus. Biopsy of such a ringed or felinized-looking esophagus (which is also often narrowed so food sticks) shows microscopic signs of allergy. The lining shows numerous eosinophils, a reddish-pink appearing white blood cell, characteristic of allergic disease. These eosinophils release chemicals, such as histamine, that cause swelling, pain, and tissue damage.
Food allergies are common in EE, although the search for a food allergy through traditional skin testing or IgE blood testing is sometimes negative. Treatment consists of avoiding known food allergens and swallowed nasal steroid sprays designed for use in the nose for nasal allergies. Although not yet specifically proven, eosinophilic esophagitis (EE) may be a variant of OAS.
Eosinophilic gastroenteritis and eosinophilic or allergic colitis also occur and can be diagnosed by biopsies of the stomach, small intestine, and colon, respectively. Allergic colitis is most commonly seen in infants with a cow’s milk protein allergy. It presents as colicky abdominal pain, diarrhoea, weight loss and bloody diarrhea in a baby fed cow’s milk or sometimes in breastfed babies whose mothers drink a lot of cow’s milk.
Allergic gastroenteritis occurs in any age group and typically presents as abdominal pain, with or without intestinal blockage or perforation; diarrhea; Anemia; weight loss; and microscopic bleeding in the intestinal tract, also known as occult blood in the stool. Such bleeding can only be detected by special chemical stool tests known as fecal occult blood testing (FOBT) or stool guaiac testing.
At least some people with food intolerances that don’t make sense based on limited dietary diary information, blood tests, biopsies, or allergy testing may have some form of OAS. In other words, the presence of known pollen or latex allergies can predispose to reactions to foods that are known to cross-react with allergies noted in OAS. However, instead of classic oral allergy syndrome symptoms, other gastrointestinal symptoms or even non-gastrointestinal symptoms may result.
Support for this concept can be found in detailed screening of individuals for food intolerance. Those with known pollen or latex allergies, known food allergies or intolerance, including gluten intolerance (celiac disease) and casein intolerance, are asked to complete a series of symptom assessments and severity rating scales, followed by a strict elimination diet. This is followed by a reassessment of response to symptoms while reintroducing foods one at a time while checking for recurrence.
This type of analysis is the basis for the Neopaleo Specific Diet. In the near future, online symptom assessments and food intolerance screening along with dietary recommendations specific to individuals will be available at www.thefooddoc.com. An online dietary symptom diary will also be available. A simplified table is available illustrating common foods that may cross-react with the broad categories of pollen allergens and latex allergy. Food intolerances are increasingly recognized as a common cause of illness and symptoms. Individualized specific dietary recommendations and elimination diet trials may be more helpful in discovering possible links to what you eat and how you feel.
Copyright 2006 The Food Doc, LLC. All rights reserved.
Pollen allergy and food sensitivity : the oral allergy syndrome and food intolerance
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