Food Allergies: General Information

Food allergies often cause itching of some form—either the mouth and throat while the food with the first few bites or the skin sometime later. Within minutes or hours, hives, nausea/vomiting, diarrhea/cramps, wheezing, coughing, chest/throat tightness, shortness of breath or rarely, a drop in blood pressure may occur (a sign of a severe allergic reaction). The severity of someone’s reaction is mostly determined by how sensitive they are to a given food and the amount of the allergen ingested. More severe reaction (anaphylaxis) may occur in asthmatics and those taking certain blood pressure medications (beta blockers). Also a food allergen combined exercise, overheating, alcohol and aspirin/NSAIDS may lead to more severe reactions.

In young children, the most common causes of food allergy are dairy, eggs, fish, soy, tree nuts and peanuts. Egg and milk allergies are frequently outgrown. Peanut allergy is usually lifelong and can be severe and sometimes fatal. Deaths from food allergy occur every year and usually occur in those who are known to be allergic. Fatalities from food allergy are more likely to occur if there is a delay in the administration of emergency medical care [or self-administration of epinephrine (EPIPEN)] and in those with asthma.   Please read Dr. Stadtmauer’s article for patients entitled Don’t Be Araid to Use Epinephrine.

The best treatment for food allergy is primary prevention (namely not becoming allergic in the first place).  That can be accomplished by introducing common allergens at a young age during the development of the immune system (about 6 months of age).  While there is no cure at this time for established food allergies, food desensitization has garnered much attention lately.  This is a promising treatment but must be done under close supervision of an experienced allergist.  For most patients, the best treatment for food allergy is avoidance.  You should educate yourself about the foods to which you are allergic.  A wealth of information is available on FARE (Food Allergy Reseach and Education) where you can find educational materials, recipes and warnings about mislabeled processed foods.

It is not easy managing food allergies because of the many sources of cross-contamination:   

  • In  Restaurants:
    • Nuts and nut oils in salad dressings and sauces
    • Milk, egg, wheat or peanut butter in sauces or marinades
    • Butter added at the end of grilling
    • Eggs in casseroles or to bind ground meats
    • Fish used in sauces
  • At Grocery:
    • Bulk foods/bins
    • Deli section (shared slicer)
    • Bakery section (shared cookie sheets)

Foods are related to each other genetically.  Therefore an allergy to one food might lead to allergic reactions to similar foods (whether or not these foods look alike).  Examples include peanut allergy that cross-reacts with another legume, lupin, that is commonly used as a flour in Europe.  Some milder cross-reactive food allergies are also sometimes related to pollen allergy, an entity known as Oral Allergy Syndrome (or the Fruit Pollen Syndrome).

Diagnosis is made by the history of the reaction, skin prick testing and blood test.  If there are doubts about the diagnosis (by history or testing) then a slow, supervised food challenge may be done.  This post by Dr. Stadtmauer clears up some of the confusion about allergy testing.

When dining out, especially in a restaurant where your language is not spoken, it is important to communicate with the staff about your food allergy.  Restaurant cards in multiple languages are recommended when eating out or travel.    Despite your best efforts to avoid allergens, sometimes restaurants intentionally mislabel inexpensive fish (for example, tilapia) as expensive fillets.

There are also many non-allergic reactions to food. These include food intolerance, stomach diseases, enzyme deficiencies, infections or toxins.

  • Gastrointestinal Disease- ulcers or irritable bowel syndrome
  • Food Intolerance-enzyme deficiency
    • Dairy products cause bloating, cramping and gas due to lactose intolerance in persons lacking lactase.
    • Alcohol may cause flushing (commonly in Asians) due to Alcohol Dehydrogenase deficiency
  • Food poisoning causing vomiting and/or diarrhea occurs when bacteria contaminate food
  • Syndromes. Chinese Restaurant Syndrome (MSG) may be associated with flushing or headache but not life-threatening allergies.
  • Celiac Disease-also known as gluten sensitive enteropathy is a genetic disease that may cause many chronic symptoms

You might want to listen to a podcast of Dr. Stadtmauer’s interview about food allergy.  Lastly, have you ever wondered why food allergies evolved?

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