Food Allergy: Basics and Beyond


Food allergies are growing food safety and public health concern. They affect 4%–6% of children and up to 4 % of adults in the United States. Food allergy symptoms are most common in babies and children, but they can appear at any age. Though less common; one can develop an allergy to foods eaten for years without a problem.

Why do food allergies happen?

The body’s immune system keeps one healthy by fighting off infections and other dangers to good health. A food allergy reaction occurs when the immune system overreacts to a food or a substance in a food, identifying it as a danger and triggering a protective response.

Which foods can be involved?

While any food can cause an adverse reaction, nine types of food account for about 90 % of the reactions; Milk, Eggs, Wheat, Soy, Peanuts, Tree nuts, Fish, Shellfish, and Sesame.

What are the symptoms of food allergies?

Symptoms of food allergy can range from mild to severe. They can present with one or more of the following: vomiting, abdominal pain, hives, tongue or throat swelling causing hoarseness or difficulty talking, inability to breathe, repetitive cough, wheezing, dizziness or feeling faint, weak pulse. Anaphylaxis is the most severe presentation of food allergy in which 2 or more of the above described symptoms happen together. This can be life threatening and has to be treated immediately. One should call 911 in case of having a life threatening reaction.

A food allergy will usually cause some sort of reaction every time the trigger food is eaten. The symptoms may be the same or different every time. The symptoms might even worsen with each exposure.

What is the timing of the reaction in relation to food?

Most food-related symptoms occur within two hours of ingestion; often they start within minutes.

Is there other kind of reaction related to food allergy?

There are some delayed reactions in the form of worsening eczema in some individuals. There are also some gastrointestinal conditions involving delayed allergies to foods; namely Eosinophilic Esophagitis. There is also a delayed food allergic condition called FPIES (food protein induced enterocolitis syndrome) which is usually seen in babies. It involves severe vomiting and diarrhea which can lead to dehydration and shock.

What is the amount of food which can trigger a reaction?

The amount of food needed to trigger an allergic reaction is different for everyone. Some people react to just a tiny exposure of food and some react after ingest a larger amount.

How is food allergy diagnosed?

You should talk about your symptoms with your primary doctor and discuss about seeing a specialist who deals with allergies. An allergist is a specialist doctor who is trained to diagnose and manage food allergies.

To make a diagnosis, the allergist will ask detailed questions about your medical history and your symptoms. They will also order skin testing and/or blood tests to arrive at a diagnosis. Skin testing involves pricking the skin with an allergen extract and a control and monitoring the area for a wheal/flare reaction (looks like a mosquito bite) . The test is not painful but the skin can be itchy where the extract is placed. A positive test does not always mean an allergy but a negative test is helpful in ruling it out. The blood tests are less accurate than the skin tests. Your allergist might use one or both types of tests to diagnose food allergies.

How is food allergy treated?

The primary way to manage a food allergy is to avoid consuming the food that triggers the allergy. There is currently no cure for food allergies; nor are there medicines to prevent reactions.

Read food labels to ensure that you don’t eat foods that contain ingredients which you are allergic to. Many ingredients have alternative names which can be confusing. Always ask about ingredients when eating at restaurants or when you are eating foods prepared by family or friends.

In case you have severe food allergy; carry an epinephrine auto injector which is prescribed by your doctor. It is a lifesaving medication which is injected into the thigh muscle in case you are having anaphylaxis. Antihistamines like Benadryl can also be used in case of mild symptoms. Talk to your allergist about having an anaphylaxis action plan and discuss treatment approach for mild symptoms.

It is especially important for children with severe food allergies in day care and school to have well documented list of food to be avoided and have an epinephrine auto injector available at all times. School personnel should know how to handle emergency situations.

What is difference between food allergy and food intolerance?

Many people who think they are allergic to a food may actually be intolerant to it. Some of the symptoms of food intolerance and food allergy are similar, but the differences between the two are very important. Proper diagnosis and distinction between food allergies and intolerance is important which can be done by an allergist.

Can I outgrow my food allergies?

It is possible for children with food allergies to grow out of them; this is especially true for foods like milk, eggs, wheat and soy. Peanut and tree nut allergies tend to be more persistent. Allergies which develop later in life tend to be lifelong. Your allergist can help in figuring this out.

I am allerigic to peanuts, is my child allergic to it?

Not necessarily, though immediate family members may be at an increased risk for food allergies. Your allergist can do simple tests to figure this out.

Research Now Suggests Early introduction of Peanuts to Infants May Prevent Food Allergy

This story reminds me of the movie, “Sleeper.” The Woody Allen movie from the 70s focuses on a man who was put into a cryogenic freeze when he died after a simple operation in a New York hospital. He woke up 200 years later and found that the world was very different. He was surprised that everyone was smoking cigarettes. This future scientist told him that research had determined that tobacco was extremely healthy for the lungs.

Of course, this is silly, but one thing rings true. As science moves forward, some old dogma turns out to be very wrong. This is the case with the thought of restricting allergenic foods until later in life. Pediatricians have been taught to tell parents that they shouldn’t give their children such foods as milk, egg, peanuts, and shellfish until the child is much older. That advice is likely the opposite of good advice.

The idea about peanut introduction early in life came from an observation that children in Israel were less likely to develop a peanut allergy than children in other parts of the world. Israeli children are fed, at a very early age, treats that contain fairly large amounts of peanuts, whereas children in England, for instance, aren’t supposed to eat peanuts until much later.

So British researchers started a study looking at the very early introduction of peanuts into the diet of infants. They found that there was a dramatic decrease (80% less peanut allergy) in the incidence of peanut allergy as children grew up. I imagine that, in the very near future, the recommendations for when to introduce allergenic foods will be drastically different than in the past.  – Neil Gershman, MD



Where can get more information?