Many people with food allergies have mild symptoms, such as a rash, runny nose or itchy eyes, when they eat small amounts of a problem food. But they may still be at risk for a potentially deadly reaction.
In the US, food allergies cause up to 30,000 emergency room visits and 200 deaths annually due to anaphylaxis, an acute reaction that can cause respiratory distress and/or a heart arrhythmia (irregular heartbeat).
Recent development: The Food Allergen Labeling and Consumer Protection Act, which went into effect in 2006, requires food manufacturers to list eight major allergens on food labels to help people with food allergies identify and avoid problem foods.
Is It Really An Allergy?
Not all reactions to food are due to allergies. Tens of millions of Americans suffer from food intolerance. A food intolerance, such as a sensitivity to the lactose in milk, can begin in childhood. The most common symptom of lactose intolerance is gastrointestinal discomfort, including diarrhea, cramping and flatulence.
Food allergies affect about 11 million to 12 million Americans. With a food allergy, the immune system mistakenly identifies as harmful the various proteins or even a single kind of protein-within one or more foods. This triggers a cascade of events that causes immune cells to respond to the "threat" by releasing large amounts of histamine and other chemicals that produce the allergic symptoms.
The most common food allergen is shellfish. Up to 2% of Americans are allergic to shrimp and/or other shellfish, such as lobster, crab and crayfish. This type of allergy often is ignored -primarily because most people tend to eat shellfish far less often than other allergenic foods, such as eggs, peanuts and fish.
Testing For Allergies
A food allergy usually can be diagnosed with a thorough medical history taken by an allergist.
The doctor will want to know...
- When do symptoms occur? Food allergies typically cause symptoms within a few minutes to several hours after exposure. Symptoms include stomach cramping, hives, lip swelling, runny nose, congestion and asthma. With a food intolerance, symptoms may not occur until the next day.
- How much did you eat? With food allergies, any exposure can trigger symptoms. For some patients, 1 mg—an amount that's almost impossible to see will provoke an allergic response. A reaction can even be triggered by kissing—or sharing utensils with—someone who has eaten a substance to which you are allergic. A skin reaction can occur from touching the substance.
With a food intolerance, symptoms usually are linked to the amount consumed. Someone who's sensitive to milk, for example, can often drink a small amount without a reaction.
Two tests can identify most food allergies. They are…
- Skin prick. Extracts of suspected foods are pricked into the skin with a needle. The appearance of a rash within a few hours—or even a few minutes—indicates a food allergy
Caution: The skin-prick test isn't advisable for patients with severe allergies. The tiny amounts of food used in the test could trigger a life-threatening reaction.
- Radioallergosorbent test (RAST). This blood test detects antibodies to specific food proteins. The test occasionally produces false positives—indicating an allergy where none is present. It's often combined with the skin-prick test for more accurate results.
People with a history of serious food reactions must carry an EpiPen. Available by prescription, it's a self-injector that delivers a dose of epinephrine. Epinephrine stimulates the heart and respiration and helps counteract deadly anaphylaxis.
Important: Use the EpiPen immediately if you experience difficulty breathing or throat constriction. Even if you take the shot promptly, get to an emergency room as soon as possible for follow-up treatments.
Also helpful: Take an antihistamine, such as Benadryl, according to label instructions. It can lessen the severity of symptoms while you get to an emergency room.
New development: Omalizumab (Xolair), a medication currently used for asthma, appears to significantly blunt reactions in food-allergy patients who receive a monthly injection of the drug. In an early study, patients who reacted to trace amounts of peanuts were able to eat eight to 10 nuts without experiencing problems. Further studies must be completed to determine whether the FDA deems it an effective—and safe—therapy for food allergies.
Avoiding Problem Foods
Because there isn't a cure for food allergies—and even trace amounts of a protein can trigger reactions—strict avoidance is the best defense…
- Always read food labels—even if you've safely eaten that product in the past. Manufacturers frequently change or add ingredients.
- Ask about "hidden" ingredients in medications. Some prescription and over-the-counter OTC) drugs, as well as vitamins and supplements, contain milk proteins or other common food allergens. This information should be on the label, but check with your doctor or pharmacist before taking any medication or supplement
- Talk to the chef or restaurant manager when eating out. The waiter or waitress doesn't always have accurate information about food ingredients and preparation. Ask to speak to the chef or manager instead and tell him/her what you're allergic to. Explain that any contact with the offending food can be life-threatening.
If you're allergic to shellfish, for example, tell the chef or manager you can't eat a hamburger that was cooked on the same grill used to cook shrimp.
Other hidden sources of food allergens: Cooking oils that are used to cook different foods. knives and cutting boards that aren't washed clean between uses.
- Wear a medical alert bracelet/necklace. Anaphylaxis can potentially cause a loss of consciousness within minutes. A medical alert bracelet/necklace lets medical personnel know that you require urgent treatment for your allergy.