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Dear Dr. K;

Dear Dr. K;

I recently underwent food allergy testing at the behest of my gastroenterologist to see if food allergies are causing or contributing to my irritable bowel syndrome.  It turns out I’m allergic to five foods.  My question is how do I determine if all five are causing my symptoms or just one or two?

That is a great question.  The guidelines I’m going to share with you were worked out in clinical research units.  In these settings patients are kept in a controlled environment (typically a hotel appended to the university hospital) and avoid the implicated (food allergy test positive) foods for two weeks.  It seems to take this long to fully “clean the system”.  Then, one food at a time is re-introduced.  In the research setting this is done double blinded and placebo controlled by putting the food to be tested inside gel-caps.  On a given day the patient may receive a placebo or an actual food.  Now, obviously this is a very tedious and protracted protocol.  But it has led to some basic rules to be used at home.

So, first of all, you need to avoid all five foods at the same time for two weeks.  If food allergy is causing your IBS, you will feel better at the end of two weeks. 

Then start adding a single food. You should have this food in “a usual portion size” and have it at least three days in a row.  If you have “tummy troubles” the very first day it could be due to the food or serendipity.  So, you need to repeat the experiment to verify. 

Now here is the hard part.  If you have symptoms you need to go back to the elimination diet until you feel well again before you try the next food.  Unfortunately, this could take up to two weeks again.  But you need a symptom reduced baseline to have clarity. 

Once you’ve tested all the foods there is another step you might need to take.  But this is necessary only if all the individual tests were negative.  This step involves testing food combos.  By way of example let’s say you tested positive to cheese, tomato and wheat.  Tested individually: no issue.  But tested together might reveal synergism.  So, pizza would be a mechanism to test all three.  Good luck, be patient. 

Omalizumab for Food Allergies

Omalizumab for Food Allergies

The FDA recently approved omalizumab (Xolair) to treat patients with food allergy including children as young as one year.  The approval came from several research trials including one recently published in the New England Journal of Medicine (NEJM) that was conducted at John’s Hopkins.  This particular study looked at allergy to peanut, cashew, egg, milk, walnut, hazelnut and wheat.  In the case of peanut allergy 67% of the test patients were able to consume 600 mg of peanut (equivalent to four peanuts) without adverse symptoms. 

The current recommendation is to only consider this therapy in people with severe (anaphylactic) food allergy.  In addition, the intent is not to enable ongoing ingestion of the food but to protect against anaphylaxis due to accidental exposure.  

An accompanying editorial in the NEJM was a bit of a devil’s advocate pointing out that the treatment is not curative but only works as long as the medication is continued.  It further argued that avoidance is still the lynch pin of therapy in severe food allergy.

The editorial did point out the potential safety net for children who otherwise run the risk of anaphylaxis from accidental exposure. 

Cross Reactive Epitopes & Food Allergy

Cross Reactive Epitopes & Food Allergy

A recent article in the Journal of Allergy and Clinical Immunology provided an update on our understanding of cross reactivity. 

First by way of definition an epitope is a discreet (usually small) portion of a molecule that is the binding target of an antibody.  In the case of allergic problems, the antibody is IgE.  By way of example think of distinguishing features that help you identify a car:  the Mercedes Star and the Dodge Ram. 

Allergy is directed at this epitope, not at the very large complete molecule.  As it turns out certain epitopes are found on both foods and airborne allergens.  The most common examples are crustaceans and dust mites, tree nuts and birch pollen, wheat and grass pollen.  The cross reactivity can be a two-way street where exposure to a food worsens an airborne allergy or vice versa.  Also, allergy shots for the airborne allergen can actually reduce the food allergy by desensitization reactivity to the shared epitope.  What will be very interesting to find out is whether desensitization to foods will help airborne allergy.  Food desensitization is still in its infancy with peanut desensitization being the main inroad in this regard.  But many academic centers have ongoing research to develop therapies for other common food allergens; milk, egg, wheat, soy and corn.  Stay tuned. 

Food Allergy/Undeclared Ingredients

Food Allergy/Undeclared Ingredients

Researchers at Utrecht University in the Netherlands recently published a study on food allergy reactions due to undeclared ingredients.

They studied 73 patients with food allergy who had a reaction even though they thought they were avoiding their known food allergies.  In 22 patients the scientists could find no explanation for the allergic attack.   But in 51 cases analysis of the offending food revealed one to four culprit allergens not listed under “ingredients”.

The most common “undeclared food” was milk followed closely by peanut and sesame.  The less common offenders were:  tree nuts, egg and celery.

The foods most commonly guilty of containing unlabeled ingredients were cookies and cakes, bread and rolls, chocolates, sauces and dried fruits.

Even tiny whiff enough to trigger allergic reaction

Even tiny whiff enough to trigger allergic reaction

A review of food reactions in children from inhalation was recently published in an issue of Allergy and Asthma Proceedings.

As an introduction, the authors remind readers we are able to smell foods because of tiny aerosolized particles of food. In some children, even this tiny amount of exposure can lead to allergic symptoms.

The foods most commonly implicated in this mischief are: fish, nuts, legumes, grains and cow milk.

Up to 10 percent of children allergic to fish will have some type of allergic response to seafood odors or fumes. Typically, this is eye itching, sneezing or wheezing.

Of interest, shellfish were much less likely to cause inhalation problems than “swimming” fish.

The incidence of airborne nut allergy was smaller with three percent of children with tree nut allergy reacting to the smell, and one percent of peanut-allergic children reacting. (Even though peanut is a legume, it was studied in the nut category because there are so many children with peanut allergy.)

Again, common symptoms seen were eye itch, sneezing and wheezing. But some children suffer hives and even anaphylaxis from nut odor inhalation.

The most common legumes to cause inhalation allergy are soy, chick peas, peanut-like lupines and green beans. The spectrum of symptoms: eye itch, sneezing and wheezing, but also intense itching in the mouth and throat in some children.

The cereal grains most likely to cause problems are rice, buckwheat and wheat. Buckwheat is more common a cause than expected because many children have ongoing exposure from buckwheat chaff being used in stuffed animals.

And while cow milk is a common cause for inhalation allergy, some children are sensitized from powdered formulas being mixed in their presence.

Also, as mentioned in a previous newsletter, some asthma inhalers contain small amounts of milk protein as a stabilizer.

Few victims, but plenty of chances to ingest

Few victims, but plenty of chances to ingest

Heads up. This article is truly only intended for a very, very select group of individuals with severe food allergy. It addresses a very special situation when foods are found as an excipient (non-active ingredient) in a medication.

Excipients are added in manufacturing to protect, support or enhance stability or bioavailabilty of an active ingredient.

The amount of food found as an excipient is truly miniscule, and therefore, 99.99-plus percent of people actually allergic to that given food would not – repeat NOT – be affected by the tiny amount found in the medicine.

Some medicines that contain trace amounts of egg include: Interferon, some probiotics, vaccines against flu, measles-mumps-rubella (MMR), rabies and yellow fever; Propofol, Ibuprofen, some multi-vitamins, Rosiglitazone and diphenhydramine.

Tiny amounts of fish protamine are found in NHP insulin.

Gelatin is found in many capsules and tablets, and in some suppositories and nicotine chewing gum. Vaccines for flu, Japanese encephalitis, MMR, rabies, tick-borne encephalitis, typhoid, varicella, yellow fever and zoster also contain it.

Milk has four allergy-causing proteins: Casamino acids are found in vaccines (DTaP, meningococcal pneumococcal, Td). Casein is found in Cefditoren, Miconazole, some probiotics and vaccines (TDaP, typhoid). Lactalbumin is found in the oral polio vaccine. And lactose is found in many tablets, capsules and granules. It is also in some asthma inhalers: Foradil, Advair, Flovent, Ventolin, Pulmicort, Spiriva, Symbicort and Asmanex.

Peanut oil is found in dimercaprol injection, progesterone capsules and valproric acid capsules.

Pine nut resin is found in fluoride tooth varnish.

Popular foods, pancake batter linked to pesky syndromes

Popular foods, pancake batter linked to pesky syndromes

Food ingestion anaphylaxis caused by mites is a newly described syndrome, as detailed by the World Allergy Organization in this month’s Journal of Allergy and Clinical Immunology. Until recently mite allergy was best recognized as a major cause for allergic rhinitis and asthma via the inhalation of the microscopic mites. Millions of allergy sufferers actually receive allergy shots for this mite allergy.  Over the years occasional case reports would appear in the medical literature about airway anaphylaxis;  that is, sudden and severe closure of the airways due to an inordinate inhalational dose of mite, such as from spilling a vacuum cleaner bag. But until recently, there had never been reports of anaphylaxis from the ingestion of mites.
The new syndrome has been dubbed oral mite anaphylaxis (OMA), or also “pancake syndrome,” because the primary source of ingested mites is from wheat flour contaminated with mites — and for some reason, this occurs most often in pancake mix.  The syndrome occurs primarily in warm, tropical or sub-tropical locations where temperature and humidity favor the proliferation of mites in certain foods.  In some cases the wheat itself was mistakenly assumed to cause the reaction because the presence of mites was not initially suspected.  Also, the patient may live in a northern clime, but have a reaction from wheat or flour mix produced in a tropical area.
Unfortunately, cooking does not inactivate the mites in terms of allergenicity.  Other common foods that have been implicated are pizza dough, beignets, polenta, grits and scones.
Mother’s milk, delayed solids: Food allergy prevention standards, but we can always learn from new data

Mother’s milk, delayed solids: Food allergy prevention standards, but we can always learn from new data

 This month’s issue of the Journal of Allergy and Clinical Immunology has a symposium on food allergy.

Until recently it has been recommended that a good strategy to reduce risk of children developing food allergy was to promote exclusive nursing as a food source, to have the mother avoid highly allergenic foods and to delay weaning with introduction of solid foods.

However, despite the implementation of this approach in a number of countries in Asia, Europe and North and South America, there has been no reduction in the incidence of food allergy. The recommendations were made based on individual facts that are true, but that unfortunately do not lead to the desired outcome.

It is definitely true that mother’s milk is the best and most complete of infant nutrition. It is also true that mother’s milk contains a host of proteins and immune globulins that provide protective immunity to the infant. It is also true that early exposure to foods other than mother’s milk can lead to the development of food allergy.

From all these facts it was assumed the feeding recommendations also would be the best course to follow.

Once the potential benefit of this dietary approach was actually studied however, it was quickly learned that it did not provide the desired results. As it turns out a crucial fact that was previously unknown makes a pivotal difference.

If infants have early exposure to non-breast milk foods through skin contact, this is what leads to allergic sensitization. This has been born out in animal model research. Paradoxically, the food allergy development through skin contact can actually be prevented by early oral exposure to the food, e.g., from parents’ hands, kisses, etc. A good example of this phenomenon has actually been recognized for quite some time and it has to do with nickel allergy.

If a child’s first exposure to nickel is from pierced ears (skin exposure), there is up to a 40 percent chance of the child developing nickel allergy. If, on the other hand the child has oral nickel exposure from placement of orthodontic braces prior to ear piercing, the risk of nickel allergy is almost zero.

At this point in time the American Academy of Allergy has no specific recommendation. There are, however, numerous randomized controlled studies that are being conducted comparing the early exposure to foods such as peanut, milk, wheat and egg versus strict avoidance of these foods. Such studies will lead to a new evidence-based recommendation on how to prevent food allergy.

Vaccine Research addresses serious worldwide uptick in food allergy

Vaccine Research addresses serious worldwide uptick in food allergy

Another part of the Journal of Allergy and Clinical Immunology’s food allergy symposium addressed European research on food vaccines. Impetus for this research is the worldwide increase in food allergy and also the increasing frequency of anaphylactic shock from food allergy.

Since vaccine therapy has proven successful in treating respiratory allergies and has also worked to prevent recurrent anaphylaxis from insects, it stands to reason that it could help eliminate food allergy and prevent food-related anaphylaxis.

Four types of vaccines for food allergy have been studied in Europe (and other countries): oral, sublingual, epicutaneous and subcutaneous.

All of these methods have proven to be of some benefit. Unfortunately, the ones that lead to the best improvement seem to have more side effects. Between the two ingestion vaccines (immunotherapy), oral immunotherapy leads to better reduction in allergy than sublingual.

The oral route commonly leads to GI side effects such as heartburn, nausea, vomiting, cramps and diarrhea. The sublingual route was much less likely to cause these symptoms, but did lead to itching and swelling in the mouth. Epinephrine shots had to be given twice as often for reactions in the oral group as compared to the sublingual group.

But patients who were successfully treated from both groups were able to ingest the implicated food – such as peanut – without going into allergic shock.

Subcutaneous immunotherapy, which is how traditional allergy shots are given, was more effective than epicutaneous immunotherapy. But once again, the more effective format led to more frequent vaccine reactions and to greater need for epinephrine to treat some of the reactions. When either of these techniques was successful, it again allowed the patient to safely ingest the offending food.

The European study group is conducting new and longer studies of these various forms of immunotherapy. The studies will include children, adolescents and adults. They also are adding studies to compare the use of pharmaceutical-grade food extracts versus the use of the entire native food as a vaccine substrate to see which works better and is safer.

New guidelines can help diagnose food allergies

New guidelines can help diagnose food allergies

The American Academy of Allergy, Asthma and Immunology (AAAAI) has just released guidelines for diagnosing and managing food allergies. These guidelines were conceived because of a lack of uniformity among physicians in testing and treating food allergy.

Frequently, pediatricians, family physicians and internists will order tests for food allergy. It is especially important that non-allergist physicians – as well as allergists – have a standard guideline for handling food allergy issues.

The AAAAI starts by pointing out that food allergy is common, but that many persons also have adverse reactions to foods that are non-allergic in origin. Proper testing/evaluation can separate these disparate conditions.

The AAAAI notes that the most common food allergens are milk, eggs, peanuts, tree nuts, shellfish, wheat and soy. The natural tendency is for an individual to outgrow the allergy. This is true for most foods, and studies have found that 80 percent of children outgrow their food allergies. This, however, is not true for peanut, tree nut and shellfish, where statistics show that only 20 percent of children outgrow these allergies.

The AAAAI makes a strong point that a positive test does not necessarily mean the patient has a true allergy to the food. What is also needed is a relevant history of prior reaction to the tested food or a confirmation of the test by an oral challenge. Oral challenges can be done at home following an elimination period. In cases of severe anaphylactic food allergies, food challenges may be done in an allergist’s office or in a hospital.

The most sensitive mechanism for testing is skin testing which measures IgE levels to the food. The RAST test, ELISA or Immunocap are blood tests for IgE.

Some labs offer a non-standard IgG food test which has no relevant value in diagnosing food allergy.