The health benefits of nuts like walnuts, pecans and almonds have been widely promoted. But for the millions of Americans with food allergies, the advice to eat nuts could be hazardous to their health. For these individuals, nuts—or other food allergens, such as shellfish and milk—could prove deadly. For reasons not yet fully understood, food allergies appear to be on the rise. While much more common in children than adults, allergies affect people of all ages and ethnicities.

Do you or your child have an undiagnosed food allergy? Get the lowdown on food allergies from Natalie Digate Muth, MPH, RD, CSCS, a dietitian, an ACE master trainer and a medical student at the University of North Carolina at Chapel Hill.

Understanding Food Allergies

The 8 most common food allergens are:

  • milk
  • eggs
  • peanuts
  • tree nuts (e.g., almonds, cashews and walnuts)
  • shellfish
  • fish
  • soy
  • wheat

The proteins in these foods cause people to itch, break out in hives and sometimes go into
anaphylactic shock, a life-threatening situation in which the heart rate drops and the breathing tubes narrow. This anaphylactic reaction occurs because the body misinterprets the food as an invader. When the perceived “invader” enters the bloodstream, the immune system creates an antibody to destroy the interloper.

With repeat exposure to the food, the antibody responds by binding to the allergen. This sets in motion a series of immunologic events, including the release of the hormone called histamine. Histamine is responsible for many food allergy symptoms, which include redness, swelling, itching, gastrointestinal symptoms and hypotension. Once the body creates an antibody to a food, an immune response happens every time that food is eaten.

For more information, see for the National Institute of Allergy and Infectious Disease pamphlet Food Allergy: An Overview.

If You Have Food Allergies

If you or your child shows the symptoms of a severe allergic reaction, such as dizziness, wheezing, falling blood pressure or difficulty breathing, take it seriously. The affected person can either be driven to a local emergency room (in mild cases) or taken via ambulance (in severe cases). Medical treatment may involve injectable epinephrine, antihistamines and other emergency measures. These medicines reverse the allergic response by restoring blood pressure, blocking further production of histamine and countering the harmful effects induced by the allergen.

After treatment of acute symptoms of an allergic reaction, you will need to be referred to an allergist, who will try to identify the food culprit through a variety of tests.

Preventing Future Reactions to Food

Once an allergy diagnosis is confirmed, you must avoid the given food to prevent an attack. This is no simple task, considering the widespread use of many common food allergens; peanuts, for example, are a common food additive.

To help ease the burden, the U.S. Food and Drug Administration (FDA) implemented a law requiring food-manufacturing companies to list on product labels any of the 8 most common allergens in food items. While this certainly will help, you must still be vigilant. People with severe allergic reactions should always carry an epinephrine pen (for injecting epinephrine, which is used to treat the reactions) and wear a medical-alert bracelet noting the specific allergy.

What About Exercise?

In certain situations, exercise can transform an otherwise benign food into a potent allergen. This is what’s known as an exercise-induced food allergy. According to the National Institute of Allergy and Infectious Disease (NIAID), “People who have this reaction only experience it after eating a specific food before exercising. As exercise increases and body temperature rises, itching and light-headedness start and allergic reactions, such as hives, may appear and even anaphylaxis may develop.”

The NIAID says the cure for this is “simple”: Until the culprit food is identified, people with a history of exercise-induced allergies should avoid eating for a couple of hours before exercising.

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©2007 by IDEA Fitness Journal. Reprint permission is granted to IDEA members by the copyright owner, IDEA Health & Fitness Inc., (800) 999-4332.