All about food allergies

Posted by Kunal Shah, M.D.
April 22, 2014

What if you had to carefully read the ingredients of every food you ate in order to avoid an allergic reaction? Life at the dinner table is very different for the small percentage of Americans who are allergic to certain foods. Recent studies show that approximately five percent of children under the age of 5, and three percent of adults are allergic to at least one food.

There is often confusion regarding the difference between a food allergy and intolerance. Often, the symptoms can be very similar. 

What is a food allergy?

If you have a food allergy, your body is overreacting to a specific food as if it were a threat. Your immune system releases an antibody called immunoglobulin E (IgE) to neutralize the food allergen. When you eat even the smallest amount of that food, the IgE antibodies sense it and tell your immune system to release a chemical called histamine, which causes many allergic symptoms such as:

  • Itching
  • Swelling
  • Hives
  • Difficulty breathing
  • Vomiting
  • Diarrhea
  • Abdominal cramps
  • Anaphylaxis (Severe, life-threatening reaction) 

Some of the most common food allergens include:

  • Eggs
  • Milk
  • Peanuts
  • Shellfish
  • Tree nuts
  • Soy
  • Fish

What is food intolerance?

Unlike an allergic reaction, the symptoms of food intolerance are almost always gastrointestinal. An intolerance means that your body does not have the correct mechanisms to digest certain foods properly. A common food intolerance is lactose intolerance, which means your body has difficulty digesting lactose, the main sugar in milk products. This, in turn, causes symptoms of bloating, abdominal pain and sometimes diarrhea.

Other intolerances that are sometimes confused with food allergy include:

  • Sensitivity to food additives such as monosodium glutamate (MSG) or artificial sweeteners.
  • Celiac disease, which is a gluten intolerance triggered by eating bread, pasta and many other foods containing wheat, barley or rye.
  • Food poisoning causes by bacteria that contaminate the food

How do you diagnose a food allergy?

An allergist is the best qualified professional to diagnose a food allergy. Your allergist will begin by taking a detailed medical history to find out whether your symptoms are an allergic reaction, a food intolerance or other health problem. Other food allergy tests include:

  • Skin test. A skin test may determine which foods, if any, trigger your allergic symptoms. In skin testing, a small extract of the food is placed on your forearm or back by a tiny pin prick just below the skin. If you’re allergic to the substance, you’ll develop a small bump.
  • Blood test. Your allergist may also take a blood sample to measure the levels of food-specific IgE. Positive blood tests do not necessarily mean that you have a food allergy, but can help put together the pieces to the puzzle.
  • Food diary. You may be asked to keep a food diary of what you eat and whether you have a reaction.
  • Elimination diet. A limited elimination diet is removing the suspected food allergen from your diet under the direction of your doctor for a few weeks. You then add the food item back into your diet to see if the symptoms return.
  • Oral food challenge. During this test, conducted in your allergist’s office, you are given small, but increasing amounts of the suspect food. Your doctor watches you to see whether a reaction occurs. A reaction only to suspected foods confirms the diagnosis of a food allergy. If you don’t have a reaction, you may be able to include that food in your diet again. 

Unfortunately for those with food allergies, there is no cure. You can only prevent the symptoms by avoiding the foods you’re allergic to. If you do come into contact with a food that causes a minor allergic reaction, you can often use antihistamine medication to reduce the symptoms. For severe reactions, you may need an emergency epinephrine injection or a trip to the emergency room. You should always wear a medical alert bracelet or necklace.

If you suspect you or a family member have a food allergy, consult with your health care provider for medical advice.

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Comments (1)

This is a great article.

Kay - 04/29/2014

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