Learn About Food Allergy
On this page you will find information on the following.
- Food Allergy vs. Intolerance
- What are the Most Common Food Allergens?
- What are the Symptoms of an Allergic Reaction?
- What is Anaphylaxis?
- How might a Child Describe an Anaphylactic Reaction?
- Food Allergy Statistics
- How are Food Allergies treated?
Is it a Food Allergy or Food Intolerance?
Have you ever heard some one say the following? “I am allergic to dairy, it upsets my stomach.” Many people think that food allergies and intolerances are the same thing. They are not. The key difference between the two lies in the immune system.
A person with food intolerance may have an adverse reaction to a food, but this reaction does not involve the immune system. A good example of intolerance is lactose intolerance. When a lactose intolerant person consumes dairy, he or she may suffer gas, bloating, cramps and diarrhea. Some people have intolerances to food additives such as yellow dye number 5, monosodium glutamate, and sulfites. These can cause adverse reactions such as hives, headache, facial pressure, chest pain or an asthmatic attack.
A true food allergy triggers a response from the immune system. Normally, our immune systems protect us from foreign harmful invaders in our bodies such as viruses and bacteria. It does this by finding the invaders and getting rid of them by producing antibodies to the foreign substance. For example, if we get sick with a cold, strep throat or the chicken pox, or if we cut our fingers or scrape our knees, our immune systems produce antibodies to fight infections and help us get better.
When a person has food allergies, the immune system interprets the proteins in normally harmless foods as foreign harmful substances. If someone with a food allergy comes into contact with a food he is allergic to, his immune system tries to fight the allergen by producing antibodies called immunoglobulin E (IgE).
The IgE antibodies attach themselves to cells called mast cells which are found in most body tissues but are especially prevalent in the typical sites of allergic reactions, including the nose, throat, lungs, skin, and gastrointestinal tract. The mast cells job is to create and store a chemical called histamine, and release it when the immune system encounters an allergen.
This histamine release causes the symptoms of an allergic reaction, which can include an itching tongue or mouth, difficulty breathing or swallowing, diarrhea, abdominal pain, hives or intense itching. This can make the person very sick.
What are the Most Common Food Allergens?
While any food can cause an allergic reaction, the proteins in dairy, soy, wheat, eggs, peanuts, tree nuts, fish and shellfish cause nine out of ten reactions in the United States. Foods are grouped into families by their origin. For example, soy, black beans and chickpeas are members of the legume family. Walnuts, brazil nuts and pine nuts are members of the tree nut family. An allergy to one member of a food family may result in an allergy to another member of the same family. More about food families
Food allergy patterns in adults are different from those of children. Some of the common patterns are.
- Children are more likely to be allergic to eggs, milk, peanuts, soy and wheat.
- Adults are more likely to be allergic to shellfish (including shrimp, lobster and crab), peanuts, tree nuts, fish and eggs.
- Allergies to milk, egg, soy and wheat are typically outgrown. Dairy is usually outgrown by age 5-6.
- Allergies to peanuts, tree nuts, fish and shellfish usually are not outgrown. About 20% of kids grow out of peanut allergy.
While some people outgrow their allergies, for some people, particularly adults, the allergy gets worse. It is common for the reactions to double every time one occurs. The first time you may get a rash, the second time hives, and the third time anaphylaxis.
What are the Symptoms of an Allergic Reaction?
Reactions can affect different parts of the body and can occur just minutes to a few hours after the food is eaten. The most common food allergy reactions include the following.
- Hives. These may occur by themselves or with other symptoms.
- Mild or severe itchy, red scaly skin called Eczema or Atopic Dermatitis.
- Asthma symptoms such as coughing, wheezing, or difficulty breathing.
- Gastrointestinal symptoms including abdominal bloating, pain and cramping, diarrhea, nausea and vomiting.
The timing of the reaction is caused by digestion. For example, seconds after eating an allergen, a person may experience swelling, tingling or itching on the lips or in the mouth, throat tightness and hoarseness. As the food moves through the digestive system, the person may experience nausea, cramping, pain, vomiting and diarrhea. Within minutes the allergens leave the digestive tract, enter the bloodstream and travel throughout the body, where they can cause a drop in blood pressure, hives or eczema, or asthma when they reach the lungs.
What is Anaphylaxis?
Food allergy reactions can range from a mild rash to a severe and life-threatening reaction called anaphylaxis, which can sometimes be fatal. The first time my five year old daughter had anaphylaxis, my husband and I had no idea it was happening. We were eating dinner at home, and she was, as energetic five year olds tend to do, squirming in her seat, joking with her sister and generally horsing around.
She began to cough. We assumed that some food or drink went down the wrong way. Then her voice changed, and she became hoarse. We did not know that hoarseness was one of the first signs of anaphylaxis. She then told us that she needed to see her doctor “right now.” At that point we knew something was wrong and rushed her to the hospital.
By the time we got to the emergency room, her lips and face were so swollen that she did not even look like herself and could barely breathe. We thank the good Lord above she had the presence of mind to tell us she needed to go to the doctor when the reaction first started. She was treated and is fine.
Food allergy causes about 30,000 cases of anaphylaxis and 150 deaths per year in the U.S., according to the American Academy of Allergy Asthma and Immunology (AAAAI). Anaphylactic allergic reactions can begin with mild symptoms such as a tingling in the mouth and throat or gastrointestinal discomfort. Within minutes it can constrict the airways in the lungs, severely lower blood pressure, sometimes resulting in a loss of consciousness and shock, and cause suffocation by the swelling of the tongue or throat.
Anaphylactic Symptoms are reversed by treatment with injectable epinephrine, antihistamines, and other emergency measures. If you are at risk for anaphylaxis, you should wear medical alert bracelets or necklaces, and carry a syringe of adrenaline (epinephrine) obtained by prescription from a physician. This is also known as an EpiPen. If you have a severe reaction, first use your medication, then immediately seek medical care. Even if you are feeling better, seek medical care immediately. The epinephrine only slows the reaction, so symptoms may reoccur a few hours later.
How Might a Child Describe an Anaphylactic Reaction?
Language children use to describe a reaction. Teach a child these symptoms, and the words to use. www.foodallergy.org/school/childdescribe.pdf
Food Allergy Statistics
- About 6% of children and 4% of adults in the U.S. have food allergy (cite – http://www.aaaai.org/media/jaci/2004/07/new_old.stm). In my daughter Emma’s kindergarten class, 3 kids out of 23 have peanut allergy.
- Children with eczema are more likely to have food allergies.
- Food allergy causes 30,000 visits to the emergency room each year, and 150 to 200 deaths each year.
How are Food Allergies Treated?
Currently, there is no cure for food allergies. The best way to treat them is to strictly avoid the foods you are allergic to, and always be prepared for emergencies. In addition to wearing medical alert bracelets or necklaces and carrying injectable epinephrine, it is important to explain your allergies, symptoms and possible reactions to those people who are around you the most. This may include family members, co-workers, friends, school teachers or day-care workers. Also, teach them what to do in an emergency. They may need to administer the epinephrine and take you to the emergency room.
How is a Food Allergy Diagnosed?
If you suspect you or your child has a food allergy, please see an immunologist or allergist who is board certified by the American Board of Allergy and Immunology (ABAI) as soon as possible. These specialists are best qualified to determine if you have a food allergy because they have specialized training from an accredited program in the prevention, diagnosis and treatment of problems involving the immune system. Board-certified immunologists and allergists have passed the examination given by the American Board of Allergy and Immunology.
The Allergy Tests
Allergy testing is helpful in confirming allergy to certain foods. In addition to food, the physician may also test for environmental allergens such as mold, dust mites, pollens or animal dander. This is important because foods may not be the only trigger for your symptoms. Initially we thought my oldest daughter was allergic to as many as 15 foods. After the immunologist performed allergy tests, we learned that she was only allergic to five foods. Most of her daily symptoms were being caused by dust mites, pollens, mold, and my parents’ cat.
What allergy tests might the immunologist or allergist perform? There is considerable controversy regarding the types of allergy testing available. While some tests have been scientifically validated and are routinely used with great success, others are experimental and have not been scientifically validated.
Once again, I can’t emphasize enough how important it is to be under the care of a board certified immunologist or allergist. These specialists should be familiar with the latest research and clinical trials regarding the testing available. They have also received specialized training in determining the appropriate test for a patient, conducting the tests, interpreting the results and recommending a course of treatment.
Here are the most common tests performed.
The Skin Test
Skin testing produces fast results and is relatively safe. It involves scratching or pricking the skin with a small amount of liquid extract made from the food. This is most often done on the back or arm. If your body makes an antibody to the extract, redness, itching or small hive called a wheal will appear within 20 minutes. This is a positive response and indicates a possible allergy. If there is no reaction, the test is negative. The tests are not 100 percent accurate, so it is important to fully discuss the results with your physician.
The RAST Test (radioallergosorbent test)
Skin testing cannot be performed on patients who have severe anaphylactic reactions or extensive eczema, because it could cause a dangerous reaction. In these cases, a doctor may conduct a blood test, such as the RAST. Blood tests measure the presence of food-specific IgE in the blood of patients. These tests are not done as often as the skin test because they are more expensive, and the results are not available immediately and are only as good as the lab that performs them. As with skin testing, the tests are not 100 percent accurate, so it is important to fully discuss the results with your physician.
This test should only be performed under the care of a physician. It requires the elimination of a suspected food allergen from the diet for a period of time, during which the patient should be carefully monitored by the physician. Later it is reintroduced, to see if symptoms reoccur. It often fails because of a variety of reasons. These can include accidental ingestion of the food, the patient may have other food allergies, or may not even have a food allergy. In the case of my oldest daughter, environmental allergies flawed the test.
This is important! Often, a person will have environmental allergies in addition to food allergies. It can be difficult to determine which is causing the adverse reactions, which is why it is so important to be under the care of a reputable immunologist or allergist.
Before conducting skin testing, we tried the elimination diet. We removed apples from my daughter’s diet, her eczema cleared up. We reintroduced apples to her at the same time we brought home a new rug. She broke out in head to toe rash. So we, and the physician we were seeing at the time, assumed she was allergic to the apples and permanently removed them from her diet.
We were wrong. Later, through skin testing by a board certified immunologist, we determined that dust mites from the new rug were the culprit, not the apples. We had unnecessarily removed a perfectly healthy food from her diet.
Also while on the elimination diet we removed dairy from her diet. We reintroduced it the same day she spent time with a relative’s cat. She got hives, so we permanently removed dairy from her diet. Skin testing later determined that she was allergic to the cat, not the dairy.
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