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Food Allergies and Intolerance

Learn the symptoms of allergies, the difference between a food allergy and a food intolerance, and the top allergenic foods.

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Food Allergies and Intolerance

Confusion about food allergy and food intolerance leaves the door open for misinterpretation. You may think the terms are synonymous, making them interchangeable. Yet they are two very different conditions that require different approaches. Misunderstanding food allergy and food intolerance may lead to unnecessary dietary restriction. Read on to clear up the confusion.

Anatomy of an Allergy
A food allergy, sometimes called food hypersensitivity, is a reaction mounted by your immune system to an allergen in food, which is almost always a protein. Your body mistakenly regards a harmless food protein as a threat to your body's well-being, and does what it can to repel it.

The first time you or your child consumes the allergen, it won't be readily apparent that the body is defending itself against the food's protein. There will be none of the myriad signs of food allergy, such as hives, swelling of the mouth and nose, or abdominal cramps. The second and third times around will be different, however. That's because after the initial encounter with an allergen, your body produced antibodies against it as a way to defend itself against subsequent "invasions."

Once the body has produced the antibodies to halt a particular allergen, you'll feel the effects of food allergy. After eating, the body releases massive amounts of histamine and other chemicals in response to allergens that trigger food allergy symptoms. According to the Food Allergy Network, it may take just seconds for an allergen to wreak havoc, but most likely the signs of food allergy appear within two hours. Sometimes it's a day or two before the allergen makes itself known with some of the symptoms listed below. Talk with your doctor if you or your child experience any of the following after eating:

  • Abdominal pain and  bloating
  • Asthma or wheezing
  • Chronic coughing
  • Cramping
  • Diarrhea
  • Hives
  • Itching and/or tightness in the throat
  • Itchy eyes
  • Nasal congestion or runny nose
  • Nausea
  • Rashes (eczema)
  • Shortness of breath
  • Sneezing
  • Swelling of the lips, mouth,  tongue, face, or throat
  • Vomiting

Foods can produce many of the same symptoms without triggering an immune response. For instance, foodborne illness is culpable for diarrhea and vomiting, two signs of food allergy. Before you blame food allergy, your doctor must confirm that your immune system is involved, since this is the hallmark of food allergy.

Avoiding Anaphylaxis
Anaphylaxis or anaphylactic shock is a severe reaction to food—most commonly peanuts, tree nuts, fish, shellfish, and eggs—that can involve several parts of the body and any number of the symptoms of food allergy. The problem occurs when too many bodily reactions occur simultaneously, essentially overwhelming your system. As a result, blood pressure drops dangerously low and your heart may beat abnormally. Without treatment, anaphylactic reactions can be lethal. Children with asthma are at greater risk for fatal or near-fatal reactions from food.

Oral Allergy Syndrome
People with hay fever symptoms may also be allergic to certain raw fruits and vegetables, nuts, and seeds. The condition is called Oral Allergy Syndrome (OAS). OAS is caused by a cross-reaction of allergens in the pollen of birch, alder, hazel, grass, ragweed, mugwort, and in certain foods. Eating fresh fruits and vegetables can leave you with itchy or swollen lips, tongue, throat, or the roof of your mouth. OAS may be more irritating than life threatening, since it tends to cause problems in the mouth, lips, and throat, rather than all over the body. OAS symptoms disappear without treatment.

The following raw foods can produce OAS. Cooking typically destroys the allergens responsible for the condition.

  • Apple
  • Apricot
  • Banana
  • Carrot
  • Cantaloupe
  • Celery
  • Cherry
  • Fennel seed
  • Hazelnut (filbert)
  • Honeydew
  • Orange
  • Parsley
  • Peach
  • Pear
  • Potato
  • Sunflower seed
  • Tomato
  • Watermelon

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