Oral allergy syndrome (OAS) is a well-recognized but little known condition. It is characterized by burning sensation or mouth pain and swelling when they eat specific foods that cross react to pollens to which you are allergic. Interestingly, the specific foods causing this reaction are well established to cross react with certain trees, grass, or weed pollens, house dust mite or latex. There are common groups of foods that cluster with certain nasal allergies. For example, ragweed allergy commonly causes an oral or gut reaction after eating melons or bananas but usually not other foods. Birch tree pollen is commonly associated with reactions to numerous foods as is latex allergy. The explanation for these reactions include similarities in protein structures as well as some chemicals in the foods.

Though this reaction is well documented in the allergy literature it is not commonly recognized or diagnosed by most doctors including some allergy specialists and many stomach specialists. Various allergy sites include lists of the common foods associated with certain pollens, dust mite or latex. However, a comprehensive list that is easy to read or interpret can be difficult to find. Also, the names of some of pollens or the common links between a group of pollens and a group of foods can be confusing.

In its classic form OAS should be easy to recognize. After eating a food associated with a pollen to which you are allergic you experience near immediate burning sensation in your mouth or throat with or without swelling. However, it is commonly recognized that frequently in medicine, symptoms do not occur in the “classic” or typical manner in a specific person. Worded another way doctors are taught "patients don't read the textbooks". Therefore, you may experience variations of the reaction such as throat swelling or tightening, burning when swallowing, a lump in the throat or a sense of swallowing difficulty but not make the connection to what you ate or what is happening to you.

You or your doctor may misinterpret your symptoms. Frequently people just assume it happened because they were having a choking spell on food that was poorly chewed, swallowed too fast, or eaten or drank while too hot or cold. Commonly, it is assumed that an esophageal (swallowing tube) disorder, especially acid reflux with a hiatal hernia is the cause. Acid reflux can cause an esophageal constriction called a stricture or ring that can result in food sticking sensation but this is usually associated with heartburn symptoms or food getting stuck prompts an upper endoscopy or scope exam. Other times, especially if occurring in an elderly person, a neurological condition like stroke or Parkinson’s disease is blamed. Sometimes doctors decide that your symptoms are due to a nervous reaction or neurosis that historically was called as globus hystericus. The hystericus portion of the term is usually dropped these days to the shorter term globus or globus sensation especially since it is not proven it is due to a psychiatric problem. However, globus may be the diagnosis arrived at if your complaint is you feel a lump in your throat and an ‘evaluation” appears to turn up nothing even if OAS was not considered or excluded.

An unusual condition that has been 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 the pediatric population but is now known to occur in adults. Classically described in teenage boys and young men who presented food sticking episodes without heartburn or acid reflux symptoms, it is associated with a strange appearance of the esophagus on endoscopy (lighted scope exam of the upper gastrointestinal tract). What the doctor doing the scope sees is your resembles a cat’s esophagus. That is it looks like it has rings (cats have cartilage rings in their esophagus, we do not) and this is referred to as "ringed esophagus" or felinization of the esophagus. On biopsy of such a ringed or felinized appearing esophagus (that is also often narrowed resulting in food sticking) microscopic signs of allergy are noted. The lining shows numerous eosinophils, a reddish pink appearing white blood cell, characteristic of allergic conditions. These eosinophils release chemicals like histamine that trigger swelling, pain, and damage to tissue.

Food allergies are commonly found to present in EE though sometimes the search for a food allergy by traditional skin tests or IgE blood tests is negative. Treatment is avoidance of known food allergens and swallowed nasal steroids sprays that are designed for use in the nose for nasal allergies. Though not specifically proven yet, eosinophilic esophagitis (EE) may be a variant of the OAS.

Eosinophilic gastroenteritis and eosinophilic or allergic colitis also exist and can be diagnosed by biopsies of the stomach, small intestine and colon respectively. Allergic colitis is typically seen in infants who have cow’s milk protein allergy. It presents as colic type abdominal pain, diarrhea, weight loss and bloody diarrhea in an infant on cow’s milk formula or sometimes in breast-fed infants whose mom is drinking a lot of cow’s milk.

Allergic gastroenteritis occurs in any age group presenting typically 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 is detectable only by special stool chemical tests known as fecal occult blood tests (FOBT) or stool guaiac testing.

At least some people with food intolerance that does not make sense on limited diet diary information, blood tests, biopsies, or allergy testing, may have a form of OAS. In other words, the presence of known pollen or latex allergy may be predisposing to reactions to foods known to cross react with allergies noted in OAS. However, instead of classic oral allergy syndrome symptoms other stomach and intestinal symptoms or even non-gastrointetinal symptoms may result.

Support of this concept can be found in detailed screening of individuals for food intolerance. Those with known pollen or latex allergies, any known food allergies or intolerance including gluten intolerance (celiac disease) and casein intolerance, are asked to complete a series of symptoms assessment and severity rating scales followed by a strict elimination diet. This is followed up by re-assessment of response of symptoms while re-introducing foods one at a time while monitoring for recurrence.

This type of analysis is the basis for the Neopaleo Specific Diet. In the near future online symptom assessment and screen for food intolerance along with dietary recommendations specific to individuals will be available at www.thefooddoc.com. An online diet symptom diary will also available. A simplified table illustrating the common foods that may cross-react with the broad categories of pollen allergens and latex allergy is available. Food intolerances are more commonly being recognized as a common cause of illness and symptoms. Individualized specific diet recommendations and elimination diet trials may be more helpful in discovering any possible links to what you are eating and how you feel.