Chew on this-according to a new report from the National Institute of Allergy and Infectious Diseases, 13% of US adults believe that they are allergic to one or more of the primary allergy-provoking foods, yet only 3% truly are allergic.

One reason: People often confuse food allergy with the more common food intolerance.

Results: When asked to explain the difference, allergist Clifford W. Bassett, MD, cited three major distinctions…

  • Allergies usually appear in childhood and may disappear over time, whereas food intolerances tend to increase with age.
  • With an allergy, the immune system mistakes a food for a harmful invader and creates antibodies that provoke a reaction whenever that food is consumed. An intolerance usually is primarily a digestive reaction (rather than an immune response) that occurs when a food irritates the gastrointestinal tract or cannot be properly digested.
  • Allergy symptoms, which can range from mild to life-threatening, may include itching, flushing, hives, dizziness, nausea, facial swelling and/or difficulty breathing. Intolerance reactions typically are milder and chiefly gastrointestinal (abdominal discomfort, bloating, diarrhea), though they sometimes include skin reactions and other non-digestive symptoms.

Editor's note: Why is it important to recognize the difference? Dr. Bassett explained that with a food allergy, you must assiduously avoid the food, since just a fraction of a teaspoon may bring on a full-blown reaction and you should keep an epinephrine auto-injector on hand to halt any potentially life-threatening reaction. If you suspect that you have a food allergy (primary culprits include shellfish, fish, peanuts, tree nuts, milk and eggs), consult an allergy specialist for testing.


In the case of a food intolerance, you may be able to identify the trigger by tracking what you eat and when symptoms arise. If you try an "elimination diet" that excludes the suspect food, check food labels so you don't unknowingly ingest something you want to avoid, Dr. Bassett said.

Note: Some people with a food intolerance find that they can have occasional small amounts of that food without bringing on symptoms.

Common food intolerances involve…

  • Lactose, a sugar in cow's milk. Up to 10% of US adults are lactose intolerant, generally because they have a deficiency of the enzyme lactase required to properly digest lactose.

Symptoms typically include abdominal pain, bloating, excessive gas and/or diarrhea. Opting for lactose-free milk or lactase enzyme supplements may allow some intolerant individuals to have more normal digestion, Dr. Bassett said.

  • Gluten, a protein found in wheat, rye and barley. Gluten intolerance appears to be more common today than it used to be. Patients often experience bloating, gas and intestinal discomfort after eating gluten grains.

Be aware: Gluten is found not only in baked goods and pastas, but also in foods containing grain derivatives—including surprising ones, such as luncheon meats, gravies, sauces, soy sauce, candy, fruit fillings, dairy-free creamer and beer-so you need to be a "food label detective," Dr. Bassett said.

  • Monosodium glutamate (MSG). Though best known as a flavor enhancer in Asian cuisine, MSG also appears in many frozen, canned and processed foods. Very sensitive people may experience flushing, a burning sensation and pressure in the face, neck and chest, as well as sudden headaches.

Food intolerances you may never have heard of include...

  • Sulfites, compounds that occur naturally in fermented products (beer, wine, champagne) and that often are added to dried fruit, grape juice, packaged foods, canned goods and other foods as a preservative. Ingesting sulfites may trigger nasal itchiness and congestion, hives and/or swelling. In people with asthma, ingesting sulfites may bring on an asthma attack.

Check labels: Aliases include sodium or potassium bisulfite...sodium or potassium metabisulfite...sulfiting agent...and sulfur dioxide.

  • Tartrazine, a dye (also called yellow dye #5) used in many beverages, chips, processed vegetables, candies and desserts. Some case reports suggest a link between tartrazine and a rare episodic skin rash. It had been thought that individuals most prone to tartrazine intolerance included those who cannot tolerate aspirin and those with asthma, but more recent research does not confirm this association, Dr. Bassett said.
  • Tyramine, a naturally occurring compound in aged cheeses, avocados, bananas, beer, chocolate, red wine and tomatoes. In sensitive individuals, Dr. Bassett said, tyramine can bring on headaches, migraines and even an elevation of blood pressure.

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