A food allergy happens when your immune system responds defensively to a specific food protein that, in reality, is not harmful to the body.
The first time you eat the offending food, the immune system responds by creating specific disease-fighting antibodies (called immunoglobulin E or IgE). When you eat the food again, the IgE antibodies spring into action, releasing large amounts of histamine in an effort to expel the "foreign invader" from the body. Histamine is a powerful chemical that can affect the respiratory system, gastrointestinal tract, skin, or cardiovascular system.
What Are the Symptoms of a Food Allergy?
- A tingling sensation of the mouth
- Swelling of the tongue and throat
- Skin rash
- Vomiting, diarrhea, or abdominal cramps
- Trouble breathing
- A drop in blood pressure
- Loss of consciousness
Severe reactions -- called anaphylaxis -- can be deadly.
Which Foods Most Often Cause Allergic Reactions?
There are eight foods that cause over 90% of food allergies in children -- cow's milk, eggs, peanuts, wheat, soy, fish, shellfish, and tree nuts (such as walnuts, pecans, and almonds).
In adults, 90% of food allergies are caused by peanuts, tree nuts, fish, and shellfish.
How Are Food Allergies Diagnosed?
Your doctor may do a radioallergosorbent blood test (RAST) to check the number of antibodies produced by your immune system. Elevated levels of certain types of antibodies can help your doctor identify specific food allergies.
By having you keep a food diary, your doctor will have a much better starting point to determine the foods that could trigger your allergies. You may be asked to eliminate all potentially allergenic foods and then add them back to your diet one at a time to see if they prompt any reaction. This is called an elimination and challenge diet.
How Are Food Allergies Treated?
The best way to cope with a food allergy is to strictly avoid the foods that cause a reaction. Mild reactions often will go away without treatment. For rashes, antihistamines may help reduce itching and may also relieve congestion and other symptoms.
For more serious reactions, corticosteroids, such as prednisone, will help to reduce swelling. In life-threatening situations, an epinephrine injection can immediately begin to reverse symptoms and is the only effective treatment option. If a doctor has prescribed an auto-injector for you, carry two at all times.
How Can I Be Prepared for Food Allergies?
Once you and your doctor have determined which foods you should avoid, stay away from them. However, it's important to maintain a healthy, nutritious diet. Ask your doctor to recommend foods that will provide the necessary nutrients.
You should also be aware of the ingredients in processed foods. Be sure to read labels. A registered dietitian can help you learn how to read food labels to discover hidden sources of food allergens. Some lotions, hair care products, soaps, and medications can also have food products -- like nuts or milk -- that might trigger allergies.
When eating out, call ahead to find out if the staff is trained to deal with food allergies. Be clear with your server about what you need and ask to speak with the manager or chef if you don’t get a good feeling. Order simply-prepared dishes and avoid salad bars or buffets.
If you’re prone to allergic reactions, ask your doctor to prescribe an epinephrine injection kit and carry two with you at all times. Let family members and co-workers know what you’re allergic to and how to help if you have a reaction. If your child is allergic, make an emergency plan with their school and teachers.
It can be tricky if you live in a family or roommate situation where one person has an allergy and the others continue to eat the problem food. Here are some tips:
- Clearly mark food packages and containers with “safe” or “unsafe.” Consider separate shelves in the refrigerator or pantry.
- Prepare food for the person with allergies first.
- If possible, have separate sets of utensils and cookware for preparing foods with and without the allergy trigger. Otherwise wash them right away.
- In between fixing safe and problem foods, thoroughly clean counters and other surfaces where you prepare meals. For some things, like peanuts, you may need to use a spray cleaner or sanitizing wipe as well as dishwashing liquid.
- Some people with allergies can get a reaction from food proteins released into the air in vapor or steam during cooking. These are rare and usually mild. Make sure a sensitive person stays away from the kitchen during cooking and for 30 minutes after.
- Wash your hands often while cooking, and before and after you eat.
- Scrub the table and kitchen counters after your meal.