Did You Know? Approximately 7% of Canadians suffer from a food allergy.Above: Peanut allergy (©iStockphoto.com/Pixel_Pig)

Allergies: they're no fun, and they can be downright dangerous. Food allergies are especially scary, since the “trigger” can be hidden in so many places. Although there is currently no cure for food allergies, some promising treatments, including immunotherapy, are being studied.

An illustration of the role of mast cells and IgE antibodies in allergic reactions. Click to enlarge (NIH Publication No. 03–5423)

If you're allergic to a certain food, it means your immune system mistakenly identifies proteins in that food as harmful or dangerous. These substances that cause allergic reactions are called allergens. The first time you are exposed to a food allergen, your B cells (a type of immune cell) produce and secrete their own protein, called immunoglobin E (IgE) antibodies. The next time you eat the same food, IgE antibodies bind to the allergens, triggering the release of chemicals, called histamines, by your mast cells (another type of immune cell). Histamines are responsible for symptoms typically associated with allergic reactions, including hives, swelling, cramps, and vomiting. Swelling is especially dangerous, because it can block airways and cause breathing problems.

Allergic reactions can be mild or severe. They are often unpredictable: you might have a mild reaction the first time and a severe one the next, or vice versa. In addition, an allergic reaction that starts out as mild can quickly become serious.

So what can be done? Unfortunately, there is currently no cure for food allergies. So the only way to prevent a reaction is to avoid exposure to the allergen (the food you're allergic to).

If you have been diagnosed with a food allergy, you may have been given an auto-injector containing epinephrine. Epinephrine acts on alpha and beta adrenergic receptors, and these receptors send signals telling the body to constrict blood vessels and relax smooth muscle, making it easier to breathe and relieving other allergy symptoms. It's also a good idea to teach friends and family how to use the injector, in case you aren't able to make the injection yourself.

Scientists are also exploring potential new treatments for food allergies.

Did You Know? The most common food allergies are to peanuts, nuts, sesame seeds, milk, eggs, fish (including shellfish), soy, wheat, and sulphites (found in wine, and as a preservative in some foods).One study recently published in the New England Journal of Medicine discusses oral immunotherapy as a potential cure. The authors of the study had young test subjects eat tiny amounts of an allergen. The dose was then slowly increased over time. After 22 months of therapy, 75% of the children in the test group were desensitized to the allergen and no longer had an allergic reaction. They were tested again 30 months after the therapy was finished. Twenty-eight percent of them still had no allergic response.

Keep in mind that this experiment is NOT to be tried at home! Do-it-yourself immunotherapy could be very dangerous and even life-threatening. Best leave it to the experts.

But if the proper doses for immunotherapy can be determined, millions of people around the world could be cured of their allergies. Some day soon, peanut butter sandwiches might once again be allowed in school lunches!

Learn More!

Health Living: Food Allergies (Health Canada)

http://www.hc-sc.gc.ca/hl-vs/iyh-vsv/food-aliment/allerg-eng.php Food and Nutrition: Food Allergies and Intolerances (Health Canada)

http://www.hc-sc.gc.ca/fn-an/securit/allerg/index-eng.php A Major Study Speeds Food-Allergy Treatments (Scientific American)

http://www.scientificamerican.com/article.cfm?id=major-study-speeds-food-allergy-treatments The immune system is not perfect – Allergies (The Microbial World)

http://www.microbiologytext.com/index.php?module=Book&func=displayarticle&art_id=402

Other References

EpiPen Prescribing Information (Mylan Inc.)

www.epipen.com/professionals/~/media/Files/epipen/DownloadableMedia/Prescribing-Information.ashx Ramsay DB et al. 2010. Mast cells in gastrointestinal disease. Gastoenterology and Hepatology. 6: 772-777.

Sophia Akl

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