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, eight types of food account for about 90 % of the reactions; Milk, Eggs, Wheat, Soy, Peanuts, Tree nuts, Fish and Shellfish.
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.
Where can get more information?
An allergy is a peculiar reaction to a substance that is not harmful to normal, non-allergic people. “Allergy,” however, is an often misunderstood term. Most people believe that an allergy refers to any uncomfortable reaction to a substance that is inhaled, eaten, or that touches the skin. Symptoms that are attributed to allergy include sneezing, wheezing, nasal irritation, cough, runny and/or stuffy nose, heartburn, bloating, diarrhea, and a variety of skin rashes.
The main confusion is that some substances can cause these symptoms in a non-allergic way. Examples of non-allergic reactions would be inhaling perfume (causing sneezing because of simple irritation) and ingesting milk (causing bloating because of a deficiency of an enzyme that helps digest sugars in the milk). Further complicating the issue is that a substance like milk can also cause true allergic reactions including hives and wheezing.
In fact, “allergy” implies that the body’s immune system is responding to a substance, or allergen, in such a way that it leads to some of the symptoms mentioned above. This occurs when the immune system sends white blood cells (as well as other cells and chemical mediators) to the site of the body where it encounters an allergen. These cells and chemicals cause changes in the tissues that lead to allergic-type symptoms. Examples of allergens include tree pollen, cat dander, dust mites, and several foods.
A requirement of such an allergic immune response is that the immune system is able to recognize a substance as being foreign – not normally present in the body. Put simply, the substance must contain molecules with certain characteristics (having a protein or large carbohydrate structure, for example) to enable it to be recognized by the immune system and give rise to an allergic response. This explains why the runny nose caused by cold air in some is not a true allergic phenomenon. People with allergic inflammation in their noses, however, are often more troubled by irritants such as smoke. A useful analogy is the following: Salt poured on intact, healthy skin causes no discomfort, but if you pour salt on an open wound it is quite painful.
Why allergy occurs in the first place is still a mystery. Some believe that allergy is simply a mistake of the immune system. That is, the immune system may “believe” that an allergen is an infectious organism such as bacteria or virus. Consequently, the immune system sends those white blood cells (such as lymphocytes) and chemicals to the tissues to ward off this false infection. Nasal congestion, for instance, might represent the immune system’s attempt to restrict the allergen (thinking it’s a virus or bacteria) from gaining deeper entry into the body.
Researchers have noted that there is an increase in the proportion of people suffering from allergies. Some believe that air pollution and heavier exposure to indoor allergens (spending more time inside tightly insulated homes) is to blame. Another interesting theory is that allergies are our society’s trade-off for being so sanitary. That is, our immune system is not as busy fighting off genuine infections as much as before, with the consequence being more frequent mistaken allergic immune responses. This theory is interesting in light of the lower incidence of allergy seen in poorer parts of the world with more exposure to parasitic infections.
Another very interesting development of the past few years has been the rise in food allergy. It turns out that the medical establishment apparently got this one wrong. They figured that having infants avoid allergy-causing foods until they were older would lead to a decrease in food allergy. So, several years ago, there were recommendations that suggested that children avoid peanuts, for instance, until they were one or two years of age. The result of these recommendations likely leads to an increase in peanut allergy. Recent studies from Israel and England have shown that exposing children to peanuts very early in life led to a decrease in the incidence of peanut allergy.
Finally, the question is what to do about treating allergic symptoms? First, it is important to determine what a person may be allergic to. The diagnosis can sometimes be made by the patient’s history alone, but allergy skin tests are needed to confirm the diagnosis. The next step is to avoid exposure to allergens. For food allergies, this is the only scientifically proven treatment. But for airborne allergens, medications can be very helpful since it may be impossible to totally avoid exposure. In addition to medications, immunotherapy (allergen injections) can be an effective remedy.
Should we be telling moms to avoid common allergy-causing foods for the first few years of life?
Conventional wisdom among pediatricians was to tell moms to hold off on feeding kids certain foods until the children were “old enough.” This came from allergy researchers who thought avoiding these foods would make the child less likely to develop an allergy to peanut, for instance. Unfortunately, it looks like this advice to parents is probably folklore. That is, there was no real hard science behind this advice. It turns out that the opposite advice is might be better. Researchers are starting to feel that children should be exposed to allergenic foods (peanut, shrimp, tree nuts, for example) early and often.
Studies looking at the effectiveness of government-based guidelines seeking to decrease peanut allergy by later introduction of peanuts found them at the very least to be ineffective, and possibly detrimental. Early feeding of allergenic foods may lead to tolerance. Tolerance is the response where the immune system learns to ignore a substance – or to not react in an allergic way.
I must clarify one important point. If a person is already allergic to a food, the only current recommended treatment is strict avoidance and that the patient should carry a self-injectable epinephrine device in case of accidental ingestion. What I am talking about here is trying to prevent children from becoming allergic to a food in the first place.
Food allergy continues to be a problem which seems to be on the increase despite the measures we take. We as doctors and parents must take the recommendations of the past with “a grain of salt.”
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