Food Allergies

What Is Food Allergy & Food Intolerance?

A bad reaction to a food doesn’t necessarily mean you have a food allergy.

For a true food allergy to be present, two things must be happen:

  1. The reaction must involve the immune system. Allergy tests determine if the immune system is involved.
  2. The reaction must create certain symptoms. Symptoms alone, however, do not prove allergy.

food allergy is a term that health experts reserve for any abnormal reaction by the body’s disease-fighting immune system to an otherwise harmless food or component of food.

Only a small fraction of the population has a genuine allergic reaction to food. In fact, in North America, only about 5 to 8 percent of children and 2 percent of adults have a true food allergy.

When a reaction to a food occurs that does not involve the body’s immune system, it is called food intolerance. This is not a food allergy.

Food intolerance stems from problems with digestion or metabolism. Usually the problem involves a defect or deficiency in an enzyme in the body, a chemical necessary for the breakdown or absorption of a particular food deficiency.

Medical experts agree that it’s important to clear up the confusion surrounding food allergy and intolerance, because the potential consequences of such confusion can be serious.

  • While food intolerance can be unpleasant, it’s rarely dangerous.
  • Individuals who have genuine food allergies, however, need to know which foods to avoid, how to recognize the symptoms of an allergic attack, and how to take steps to prevent or short-circuit a severe allergic reaction.

Facts about food allergy

  • Surveys have found that as many as one-third of all adults believe they have food allergies. However, in North America, only about 5 to 8 percent of children and 2 percent of adults have a true food allergy.
  • Food allergy usually first appears in childhood, but it can start at any age.
  • Most people who are allergic to foods have other allergies, such as hay fever or allergies to certain medications.
  • Allergic tendencies seem to run in families. However, with food allergies, it is common for only a single family member to be food allergic.
  • The best treatment for food allergy is to avoid eating the problem foods.


What Causes Food Allergy?

Food allergies occur when the immune system mounts an attack on certain proteins in certain foods. The substances in the food that trigger this immune-system response are called allergens.

The immune system is a complex network of cells and molecules that help defend the body against foreign substances. When a properly functioning immune system detects a foreign substance, it responds to this threat by producing proteins called antibodies against the invaders. The antibodies will recognize and attack this foreign substance when they next encounter it. This “battle” is what causes the allergy symptoms.

In food allergy:

  • The immune system mistakenly sees a harmless substance in the food as harmful, and churns out antibodies-known as immunoglobulin E (IgE) – to attack it.
  • These antibodies will circulate in the blood, attached to special cells called mast cells, which are part of the immune system. This occurs in order to protect against future invasion by that substance.
  • The next time a person eats that food, the substance to which he is allergic (the allergen) enters the body, and attaches to the IgE on mast cells.
  • The mast cells respond by releasing a host of powerful chemicals, including histamine, to ‘protect’ the body. This produces allergic symptoms.

Histamine contributes to inflammation and causes symptoms such as swelling on the skin and itching. It is responsible for the hives, or welts, that appear on the skin when a doctor tests for allergy. These hives show the presence of IgE and are one of the best indications of allergy.

Nice To Know:

Allergic symptoms can start within minutes or an hour or two after eating the food. In people who are extremely allergic to a food, merely inhaling miniscule amounts of the food or touching the food is enough to trigger a reaction. However merely touching the food rarely causes a systemic reaction. In fact, it is often quite surprising that a peanut allergic individual may get peanut butter on her skin without having a systemic reaction.


What Is Food Intolerance?

Very often, people mistake food intolerance for food allergy. Food intolerance is much more common than food allergy, and is the less serious of the two conditions.

Food intolerance is an exaggerated or abnormal physical reaction to a food or food additive (such as an artificial coloring or preservative) that does not involve an immune reaction. A chemical deficiency in the body is usually the cause of the problem.

It has nothing to do with food allergy because the reaction does not involve the body’s immune system.

Causes of food intolerance

Carbohydrate intolerance

Causes Of Food Intolerance

Several factors may cause a person to have an adverse reaction to food. Sometimes a person’s body will react to chemicals found naturally in foods. For example, some people get a headache after eating certain cheeses and other foods that contain a compound called tyramine. In other cases, psychological factors play a role in food intolerance.

  1. Carbohydrate intolerance. Some people cannot digest certain carbohydrates, compounds that furnish most of the energy needed in a healthy diet. Carbohydrates exist as simple sugars (sucrose, glucose, fructose, and lactose) or as glucose polymers (complex carbohydrates), such as glycogen and cellulose.
  2. Celiac disease. This disorder is caused by an intolerance to gluten, the protein found in wheat and a few other grains. In celiac disease, the cells lining the small intestine are damaged and prevent the normal absorption of food constituents, particularly fats. Celiac disease involves an immune response. However, this response does not involve IgE, an antibody involved in the allergic response. Common symptoms are gas and bloating.
  3. Toxicologic reactions and food poisoning. Foods may contain toxins that are naturally part of the food or that were added by mistake during manufacturing, shipping, or handling. For instance, some types of fish (especially tuna and mackerel) contain histadine that is converted to histamine with improper storage, which can cause an adverse reaction if the fish is stored and/or prepared improperly. Food poisoning results from contamination with bacteria or other microorganisms. Symptoms of food poisoning and histamine toxicity may closely resemble symptoms of allergic reactions.
  4. Pharmacological effects. Some foods produce symptoms that resemble reactions to drugs. For example, caffeine found in coffee, tea, and other products may cause a rapid heartbeat, sleeplessness and other effects.
  5. Psychological reactions. Psychological factors play a role in food intolerance, causing people to react to a particular food because of smell or memories, for example.

Carbohydrate Intolerance

People with food intolerance most commonly suffer from a form of carbohydrate intolerance. In many of these cases, individuals have problems digesting a carbohydrate called lactose (milk sugar). In other cases, the problem involves the digestion of sugars often found in fruit juices.

Lactose intolerance occurs when an individual is deficient in lactase, an intestinal enzyme the body needs to digest the lactose in milk and other dairy products. As a result, the undigested lactose remains in the intestines, causing abdominal cramps, bloating, and diarrhea.

Nice To Know:

A blood test or a breath test can help diagnose lactose intolerance.

Carbohydrate malabsorption syndrome, which mainly affects young children, involves the inability to digest sugars, such as sucrose, maltose, and sorbitol. A young child who gets diarrhea from drinking too much fruit juice probably cannot tolerate complex sugars.

Nice To Know:

In some children, fruit and fruit juice can cause rashes. Doctors do not know what causes this reaction. They suspect, however, that physical contact with the fruit causes the irritation, rather than an internal reaction. These reactions usually disappear between the child’s 3rd and 4th birthday.


What Are The Symptoms Of Food Allergy?

In an allergy attack, the symptoms experienced depend on where in the body histamine is released. Allergic reactions to foods most often involve the skin, the stomach and intestines (digestive tract), and the mouth and airways (respiratory system). A life-threatening reaction may involve all parts of the body including the cardiovascular system so that the individual goes into shock (the blood pressure falls dangerously low). A severe reaction could start very suddenly and involve only a fall in blood pressure (shock). It is important to know that a life-threatening reaction may occur with no skin symptoms.

Symptoms may appear within minutes or as long as several hours after eating the allergy-provoking food.

Skin symptoms

Digestive symptoms

Respiratory symptoms

Life-threatening reactions (anaphylaxis)

Skin Symptoms

An allergic reaction may cause:

  • Hives (urticaria)
  • Itchy, scaly rash called eczema (or atopic dermatitis)
  • Redness or flushing (erythema)
  • Swelling (edema)

Digestive Symptoms

An allergy affecting the digestive system may cause:

  • Stomach pain
  • Nausea
  • Vomiting
  • Diarrhea

Respiratory Symptoms

Common respiratory symptoms from an allergic reaction include:

  • Sneezing
  • Coughing
  • Runny nose
  • Wheezing
  • Closing of the throat and breathing difficulties, as part of a severe allergic reaction known as anaphylaxis
  • Itchy, watery eyes are often included with respiratory symptoms.

Life-Threatening Reactions (Anaphylaxis)

The most severe allergic reaction is anaphylaxis, or anaphylactic shock, a severe reaction that involves most of the body. Anaphylaxis can affect several parts of the body at the same time, including the skin and the digestive and respiratory systems or it might just involve respiratory or cardiovascular symptoms.

In addition to producing the symptoms of food allergy, it may also lead to difficulty in breathing, falling blood pressure and unconsciousness.

Although very rare, anaphylaxis can be fatal. Each year, about 150 people in the United States die of food-related anaphylaxis.

Need To Know:

People who have had a severe allergic reaction need to take special precautions in avoiding the allergy-causing food. In addition, they should always carry injectable epinephrine, a drug that can stop an anaphylactic reaction. This is available at pharmacies with a doctor’s prescription.


Which Foods Cause Allergic Reactions?

Virtually any food can trigger an allergic response. However, studies have found that 80 to 90 percent of children with food allergies are allergic to one or more of these foods:

  • Eggs
  • Peanuts
  • Milk
  • Wheat
  • Soy

Other common triggers include:

  • Tree nuts (such as almonds, pecans, cashews, Brazil nuts and walnuts)
  • Fish and shellfish (for example, crab and shrimp)

Various other foods and certain food additives and spices may cause allergic reactions.

Nice To Know:

Many people think that chocolate and corn contain common allergens. However, these foods rarely cause a genuine allergic reaction. In addition, the immune system never recognizes sugar as an allergen.


Sometimes, an individual’s allergic reaction to a particular food extends to other foods that contain similar allergens, a phenomenon called cross-reactivity. For example, someone who is allergic to peanuts may also have a problem with other legumes, such as soybeans or peas. However, the vast majority of food-allergic individuals rarely react to other legumes. In fact, more peanut-allergic children seem to be allergic to eggs or tree nuts than to other legumes. They often “lose” their egg allergy as they grow older.

Cross-reactions can develop between foods with allergens similar to those of other allergy-provoking substances, such as plant pollens. Researchers have found, for example, that some people who suffer hay fever symptoms when they inhale birch pollen also have an allergic reaction when they eat kiwi fruit or apples. The table below shows examples of these cross-reactions.

Allergy to these plant pollens may sometimes cause allergy to certain foods

Foods that can cause allergic symptoms in those allergic to certain plant pollens


Hazelnut (filbert)










Melons (watermelon, cantaloupe, honeydew)


Chamomile tea

Nice To Know:

Q. Can MSG or other food additives cause allergic reactions?

A. Many studies have shown that additives such as monosodium glutamate (MSG), the sugar substitute aspartame, and food dyes do not cause allergic reactions. Studies of MSG have shown that most symptoms attributed to MSG cannot be reproduced during blinded MSG challenges. However, in some sensitive people, food additives can cause an adverse reaction. This sensitivity is almost always an example of food intolerance, rather than true allergy.


How Do I Find Out If I Have Food Allergies?

If you think you have food allergies, you should see an allergist, a physician who specializes in diagnosing and treating allergies. If you try to diagnose the problem yourself, you run the risk of removing too many foods from your diet and losing important nutrients.

Before making a diagnosis, an allergist will take your medical history and ask whether you have a family history of allergies. The doctor will ask detailed questions aimed at uncovering a possible relationship between the symptoms and your diet, such as:

  • What kinds of symptoms does the suspected food or foods produce?
  • How much time elapses between eating the food and the onset of symptoms?
  • How much of the food do you have to eat to trigger a reaction?
  • How many times has eating the food caused a reaction?
  • When was the last time you had a reaction to the food?

An allergist will also use diagnostic tools, including:

A Food diary

Elimination diet

Skin tests

Blood tests

Food challenge

Bowel biopsy

A Food Diary

A food diary is a daily list of all the foods you eat, when you eat them, any symptoms that occur and how long between eating and symptoms

A person with a suspected allergy may be asked to keep a food diary for a few weeks, recording in detail the foods eaten and the appearance and severity of symptoms experienced.

While the food diary cannot prove that a particular food causes certain symptoms, it can indicate possible links between foods and symptoms that might otherwise go unnoticed.

It may be more helpful to maintain an “event” diary. When symptoms occur record all the food eaten at the previous meal. This may identify the problem much more quickly and with less effort.

Nice To Know:

If you suspect you have a food allergy, start a food diary before your first appointment with your allergist. It is particularly helpful to make a list of foods eaten in the few hours before a reaction.

Elimination Diet

An elimination diet is one from which foods suspected of causing an allergic reaction are removed for as long as several weeks. The physician usually provides a list of foods that are permitted or forbidden during this time.

  • You will be asked to eliminate the suspected foods for about two weeks. (You must be certain that a diet lasting longer than two weeks is nutritionally adequate.)
  • You’ll note whether your symptoms disappear during the diet.
  • In some cases, the doctor will ask you to reintroduce the foods back into your diet one at a time, and you’ll note whether symptoms return after you start eating the foods again. This reintroduction process is similar to a procedure known as a food challenge.

Need To Know:

Consult your doctor before beginning an extensive elimination diet. A doctor’s supervision will insure that you do not remove too many foods from your diet.

Long-term elimination diets are also a treatment of food allergy.

Skin Tests

Skin testing can help pinpoint which foods trigger allergic reactions in people who have a true food allergy. It can also help rule out a food allergy when the problem is actually a food intolerance.

Skin tests are useful in detecting food allergies, but they are not foolproof. Allergy skin tests detect only the presence of antibodies. They cannot make an accurate determination that an allergy exists.

The least expensive allergy skin test is the skin prick or puncture test. The physician places a droplet with an extract of the suspect food on the skin, and then uses a needle (or special device) to puncture the top layer of skin through the droplet. (If the physician scratches the skin through the liquid allergen, it’s called a scratch test, a test that is rarely used now.) In recent years several new skin testing devices have been introduced into allergy practice.

If a raised bump surrounded by an area of redness (known as a wheal or hive) forms within 15 to 20 minutes, the skin test is positive. In other words, the person has an antibody for that allergen.

  • A positive response does not necessarily mean that the person has a food allergy. Many people, especially those with a family history of allergy, can have a positive test result and experience no allergic symptoms when they eat the food. You do not have an allergy unless you have symptoms as well as an immune response to the allergen.
  • When there is no reaction to the allergen, the skin test is negative. A negative result almost always means the person is not allergic to the most common food allergens. Sometimes, however, a person with an allergy will still test negative. This is called a false-negative result. A false negative may happen, for instance, in young infants with poor skin reactivity, or if the skin testing material is not reliable.

Nice To Know:

To test reactions to fruits, vegetables, and some other foods, physicians use a “fresh food” skin test. There are several techniques for accomplishing this procedure, but it always involves fresh food.

In some cases, a physician will inject the allergen under the patient’s skin. Doctors do not use this “intradermal” (within the skin) test as often as the skin prick test because it has a greater chance of causing a severe, systemic (whole-body) reaction if someone is very allergic. It is also less accurate than the skin prick test.

Blood Tests

A blood test called the radioallergosorbent test (RAST) is also useful in the diagnosis of food allergies. It measures levels of IgE antibodies specific to certain allergens in a blood sample.

The IgE RAST does not have the side effects associated with the skin prick test (itchy hives). However, the RAST is more expensive and less immediate than the skin prick test. Individuals must wait to get test results back from a lab. It is also less sensitive than skin testing most of the time, and sometimes the quality control of the test is a problem. A new version of the RAST (CAP RAST) may give more accurate diagnosis for a few foods. (Recently it has become possible for individuals to have blood tests for allergy ordered and performed with minimal or no physician involvement. However, making changes to the diet without skilled interpretation and advice may be harmful or even dangerous. It may also make life needless unpleasant by removing foods from the diet that are not causing harm.)

Food Challenge

The only test that can definitively diagnose food allergy is a procedure known as a food challenge. In this procedure, the person is given either a food suspected of causing allergy or a placebo, a food that will not cause an allergic reaction. In some cases, the suspected food is hidden in another food or in capsules so that the patient cannot recognize it.

It is often a double-blind procedure, in which neither the person nor the physician can distinguish the food from the placebo, thus ruling out the possibility that the person’s or the physician’s expectations are influencing the results.

A double-blind food challenge rules out the possibility of a psychological reaction (when symptoms occur because the individual thinks he or she has a food allergy).

Nice To Know:

Studies show that less than half of all people who suspect they have a food allergy, test positive for food allergy in a double-blind food challenge.

Need To Know:

People who have had severe food reactions are allowed to participate in food challenge only under very special conditions because the procedure itself could be life-threatening.

Bowel Biopsy

In rare instances, a food allergy or food intolerance may cause intestinal damage.

biopsy of the small bowel (intestine) may be performed on people who have frequent diarrhea and cannot absorb certain nutrients. The biopsy is especially useful for diagnosing food-allergy due togastroenteropathies (inflammation of the lining of the stomach and intestinal tract) and celiac disease, which damages the intestinal lining.

Biopsy of the large intestine is helpful in children with food-induced enterocolitis (inflammation of both the colon and the small intestine) and colitisinflammation of the colon. Colitis is a condition in which drinking milk can cause diarrhea and blood in the stools.

How Is Food Allergy Treated?

Once an allergy is diagnosed, strict avoidance of the offending food (or foods) is the only proven method of managing the allergy. There is no medical cure for food allergy. However, within the next few years there will be safe and effective vaccines for food allergies.

By strictly avoiding the food for one or two years, approximately one-third of children and adults can lose their sensitivity to that food. But few children or adults outgrow their allergies to peanuts, tree nuts, and shellfish.

Need To Know:

According to allergists, if you have had a severe reaction to a food, you should never eat it again. The chances are more likely than not that you will not lose your sensitivity to that food. Whether the vaccines that are being developed will allow you to eat forbidden foods will have to be determined by careful and continuous studies.

Although there are no medications currently available to treat food allergies, there are drugs on the market to treat symptoms of food allergies. The proper treatment depends on the severity of the allergic reaction.

  • Antihistamines can help control mild reactions. These drugs have side effects, however. Over-the-counter antihistamines cause drowsiness. Your doctor can prescribe an antihistamine that will not make you sleepy.
  • Asthma medication can be useful for people who wheeze during an allergic reaction. In rare instances, food allergies may bring on an asthma attack. These attacks may be very severe.
  • Epinephrine is used to treat anaphylaxis, a life-threatening complication of food allergy. Doctors advise people with severe food allergies always to carry a self-injecting device loaded with epinephrine or a kit containing a needle and syringe and to inject themselves at the first sign or symptoms.

How-To Information:

Epinephrine usually stops an anaphylactic attack. However, a person who is having an anaphylaxis reaction also needs to seek medical attention immediately, because the problem may suddenly worsen even after treatment with epinephrine.

  • Call 911 or your local emergency number.
  • Tell the dispatcher that you are having a severe allergic reaction and the emergency response team should bring more epinephrine.
  • You should travel by ambulance to the nearest hospital.


How To Cope With Food Allergy

Most people with food allergies will be put on an elimination diet (one from which foods suspected of causing an allergic reaction are removed). It may be difficult to stop eating some foods, such as those made with wheat or milk. Fortunately, there are many foods on the market that substitute for the more common allergy-provoking foods.

Creating a food plan

Avoiding accidental ingestion

Creating A Food Plan

For help in restricting your diet after a food allergy diagnosis, consult your doctor or a registered dietitian. Dietitians can help design a food plan, suggest alternative foods or ingredients to replace forbidden ones, and provide instruction on reading food labels.

You may find it helpful to use an allergy-free cookbook, which gives recipes that omit common food allergens. Prepared allergen-free items, such as rice bread and soy beverages, are available at health food stores and some grocery stores.

It is not always possible to avoid the offending food. Your physician may give you medication to treat symptoms resulting from food allergies.

Need To Know:

A special note: individuals with wheat allergy are being told that they may eat spelt grain products. However, if you have true wheat allergy, you will react to spelt as well, and this is an unsafe substitution.

Need To Know:

A word of warning about elimination diets

They should not be too restrictive and they must be nutritionally balanced. Sometimes people allow their food restrictions to reach such extremes that they develop food aversions verging on eating disorders. Proper diagnosis and counseling by an allergist and a dietitian are crucial in maintaining a nutritionally complete diet.

Avoiding Accidental Ingestion

Despite precautions, people with histories of food reactions sometimes unknowingly consume a food to which they are allergic. This can happen when the person is unaware of an ingredient in a dish someone else has prepared. Or perhaps the offending ingredient is not on the label or is expressed in a term that does not clearly describe the ingredient.

People with severe food allergies need to be aware that tiny amounts of allergens left on pots, pans, and cooking utensils can contaminate other foods (cross-contamination now also termed “cross-contact”). To avoid this kind of danger, people with severe food allergies are advised to make certain that pots, pans, and cooking utensils are carefully washed with soap and water after each use to remove any traces of forbidden foods.

How-To Information:

How to avoid allergy-provoking foods

Read all food product labels.

  • Read the ingredient list on food labels carefully to check for foods that are off-limits.
  • Be especially careful with foods that have hydrolyzed protein on the label. This is usually a vegetable protein, but sometimes tuna fish or hot dogs contain hydrolyzed milk protein. This milk protein is not safe for people who are very allergic to milk.
  • Since food manufacturers often change ingredients, you must always read labels, even ones on foods you are familiar with.

Ask about ingredients.

  • When you eat dishes served in restaurants or by friends, ask whether the meal contains the specific food or foods you are allergic to.
  • Be aware that common recipes sometimes contain unusual ingredients. One person who was very allergic to peanuts died after eating chili containing peanut butter.
  • If you are in a restaurant, be sure that the servers can communicate your questions and concerns to the kitchen staff.

Ask about preparation.

  • Ask the cook how the food was prepared.
  • Food sometimes is cooked in peanut oil, for instance. Peanut oil that is not highly purified (as in a cold-pressed or natural oil) will have enough peanut protein to create a reaction in someone allergic to peanuts.
  • Also, peanuts cooked in any oil (canola, olive) will make the oil peanut-protein (allergen) containing oil; using the oil may cause an allergy. If there is any uncertainty about the oil, do not eat it.

Don’t take a chance.

  • Question restaurant staff about ingredients.
  • If the server does not know what is in a dish, ask the chef.
  • Don’t eat the food-or leave the restaurant-if you are not certain about the ingredients.

Protect your child.

  • If you have a child with food allergies, tell your child’s caregivers what foods your child must avoid.
  • Make sure the adults know what to do in case of a severe food reaction.
  • Encourage your child to ask whether foods contain allergens.

Bring your own food to parties.

  • If you have many food allergies or intolerances, you may want to bring a dish that you know you can safely eat when you go to a party.


Controversial Tests And Treatments for Food Allergies

There are some questionable practices for diagnosis and treatment of food allergies. Tests that are not scientifically valid and are considered experimental include:

  • Blood tests that determine food immune complexes and IgG food antibodies: Such tests measure substances that all normal people have in their blood. Food immune complexes form after food digestion. IgG includes most of the protective antibodies, including those that form when you receive a vaccine or after an infection. It is unclear whether people with allergies make abnormal amounts of these substances.
  • Cytotoxic test: This test involves adding a food allergen to someone’s blood sample and examining the reaction of white blood cells under a microscope. If the cells change shape, decrease or die, the person is thought to be allergic to that food. No proof exists that this test is effective for diagnosing food allergy.
  • Provocation and neutralization: In the subcutaneous (under the skin) form of this test, a food extract is injected under the skin. In the sublingual (under the tongue) form, the food extract is placed under the person’s tongue. If the person has an allergic reaction, he or she receives more of the substance. The belief is that the second dose neutralizes, or relieves, the symptoms. In reality, it can cause a severe allergic reaction.

    Some doctors use provocation and neutralization to try to desensitize allergic people to foods. But the technique has been found to be ineffective for both diagnosis and treatment of allergies.

How-To Information:

Consult a board-certified allergist or physician for food allergy testing. If you are uncertain about the procedure, don’t hesitate to ask questions or to get a second opinion.


Food Allergies: Frequently Asked Questions

Here are some frequently asked questions related to Food Allergies And Intolerance.

Q: What is the difference between food allergy and food intolerance?

A: Food allergy involves a reaction of the body’s immune systemfood intolerance does not. Food intolerance stems from problems with digestion or metabolism-the way the body breaks down food-usually because of an enzyme deficiency. Food intolerance rarely causes life-threatening reactions, as is possible with food allergy. A common symptom of food allergy is hives on the skin.

Q: Which foods most commonly cause allergic reactions?

A: The most common food allergies are to eggs, peanuts, tree nuts (such as almonds, pecans, cashews, Brazil nuts and walnuts), milk, wheat, soy, fish, and shellfish.

Q: Are food allergies inherited?

A: Allergies do tend to run in families. But for food allergy, it is common for only a single family member to be food allergic.

Q: Will my child outgrow food allergies?

A: Most children outgrow their food allergies after avoiding eating the foods for a time. Fewer, however, outgrow their allergies to peanuts and tree nuts.

Q: Can breast-feeding prevent my baby from getting food allergies?

A: Some experts believe that breast-feeding protects against food allergies developing later in life. Others think that breast-feeding delays the onset of food allergies, rather than prevents them. Still, many doctors recommend that you breast-feed your baby for at least six months if you have a strong family history of allergy. Babies are not allergic to proteins made in the breast. However, a baby can react to a food the mother eats.

Q: Is there a cure for food allergies?

A: Science has yet to find a cure for true food allergies. The best approach to avoiding reactions is to eliminate the problem food from your diet. Physicians hope the vaccines being developed will control food allergy even if they do not cure the condition.

Q: Can sugar or other foods influence behavior?

A: Whether foods can directly cause behavior changes such as hyperactivity, fatigue, or irritability is controversial. Scientific studies in which children unknowingly were fed sugar failed to conclude that sugar causes notable behavior changes. Likewise, there is no evidence to support the claim that certain foods can influence behavior. Most likely, a behavior change comes because people believe that eating a food makes a difference, rather than through any physical effect. Food additivesmay be another story, but it takes a large amount of additives to make people hyperactive, and it is difficult to reproduce this evidence consistently. At this time, it is doubtful that food additives cause reactions in very many individuals.

Q: Can food allergies cause or aggravate chronic illnesses?

A: Claims that link food allergies to arthritis, epilepsy, depression and environmental illness are unconfirmed and controversial. Eliminating certain foods from the diet may be helpful, however, for some people who suffer from migraine headaches or arthritis. Studies have shown a link between migraines and some foods in rare cases. In only one well documented case, milk was shown to aggravate arthritis.

Q: What foods are linked to migraine headaches?

A: Foods known to trigger migraine headaches include alcohol, especially red wine; foods with tyramine, such as aged cheese; foods containing nitrates, including cold cuts and bacon; chocolate; drinks containing caffeine; and foods with monosodium glutamate (MSG). Surprisingly, however, there are few, if any, blinded studies confirming these commonly held conclusions.

Q: Can MSG or other food additives cause allergic reactions?

A: Many studies have shown that additives such as monosodium glutamate (MSG), the sugar substitute aspartame and several food dyes do not cause allergic reactions. Studies of MSG have shown that most symptoms attributed to MSG cannot be reproduced during blinded MSG challenges. However, in some sensitive people, food additives can cause an adverse reaction. This sensitivity is almost always an example of food intolerance, rather than true allergy.

Q: What is sulfite sensitivity?

A: Some people are sensitive to sulfites, preservatives found in wine, beer and some prepared foods, especially dried fruits. Reactions in a small number of people include severe asthma attacks and breathing difficulties. Sulfite sensitivity, however, is not considered an allergy.

Food Allergies: Putting It All Together

Here is a summary of the important facts and information related to Food Allergies And Intolerance.

  • People have adverse reactions to foods for many reasons other than allergies.
  • Food allergy is much less common than most people think; less than 2 percent of U.S. adults have genuine food allergies.
  • The following foods account for about 90 percent of food allergies: eggs, peanuts, milk, wheat, soy, tree nuts, fish, and shellfish.
  • People often blame chocolate and corn for allergies, but these foods rarely cause allergic reactions. Sugar does not produce an allergic reaction.
  • Allergic reactions to food most commonly affect the skin and the digestive tract.
  • Anaphylactic reactions to food are rare but can be fatal.
  • Allergy skin tests detect only the presence of antibodies. They cannot make an accurate determination that an allergy exists.
  • The most reliable test for food allergy is the double-blind, placebo-controlled food challenge, it is the gold-standard for food allergy diagnosis and is crucial in research studies.
  • The best approach to managing food allergy is to stop eating the offending food.
  • Vaccine treatments for food allergy are being developed.

Food Allergies: Glossary

Here are definitions of medical terms related to Food Allergies And Intolerance.

Additive: A substance, such as an artificial color or preservative, added to food.

Allergen: A substance that produces an allergic reaction.

Allergy: The body’s exaggerated reaction to a foreign substance that is harmless to most people. For a reaction to be considered an allergic reaction, it must involve the immune system. The foreign substance may be eaten, inhaled or injected.

Anaphylaxis: A severe allergic reaction that involves much of the body-the respiratory system, skin, digestive tract and, sometimes, blood circulation. Symptoms include cough, wheezing, closing of the throat, runny nose, hives and swelling, nausea, vomiting, diarrhea, cramps and a drop in blood pressure that may cause loss of consciousness and even death. However it is important to know that a life-threatening or fatal reaction may occur without skin symptoms.

Antibody: A protein made by the body’s immune system to combat foreign substance, most often a foreign protein.

Antihistamine: A medicine used to counteract histamine, a chemical released by the body in an allergic reaction, which contributes to the inflammation.

Atopic dermatitis: See eczema.

Biopsy: Removal of tissue for examination.

Cross contamination: When a small amount of food accidentally gets into another food.

Double-blind study: A trial in which neither the patient nor physician can distinguish between the real thing (for example a pill) and the inactive substance(the dummy pill).

Eczema (atopic dermatitis): A non-scarring skin rash that usually begins in childhood. Allergy may be involved in less than half of all children with eczema.

Enzyme: A protein that helps other chemical reactions occur, but isn’t itself affected in the reaction.

Epinephrine (also known as adrenaline): A hormone, also used as a drug used to treat anaphylactic shock.

Histamine: A chemical in certain body cells, which contributes to inflammation and causes itching, swelling, sneezing and other allergic symptoms.

Hives: An allergic condition characterized by red, slightly swollen eruptions or itchy lumps on the skin.

hypersensitivity: Another word for allergy.

IgE (Immunoglobulin E): One type of antibody that defends the body against outside invaders. When certain proteins interact with specidic IgE antibodies the resulting reaction is an allergic reaction.

Immune system: The body’s defense system, which fights disease and infections.

Immunoglobulin: A group of proteins known as antibodies that are involved in defending the body against outside invaders.

Inflammation: A protective reaction to an injury that may cause severe discomfort.

Mast cells: Cells present close to body surfaces (such as the skin and intestines), which produce and release chemicals-for instance, histamine-which then produce allergic symptoms.

Metabolism: The building and breaking that occurs continually in the body.

Placebo: A substance used in testing that has no known physical effect on the body. It may have a powerful psychological effect, however.

Toxin: A poison.

Vaccine: An injection given to induce immunity and protect against a certain germ.

Food Allergies: Additional Sources Of Information

Here are some reliable sources that can provide more information on Food Allergies And Intolerance.


American Academy of Allergy, Asthma & Immunology 
Phone: 1-800-822-ASMA (2762)

Asthma and Allergy Foundation of America 
Phone: 1-800-7-ASTHMA (278462)

The Food Allergy Network 
Phone: 1-800-929-4040

Web articles

“Food Allergy and Intolerances”

Summary: This fact sheet from the National Institutes of Health provides a thorough look at food allergies, including exercise-induced food allergy. It also gives links to information about lactose intolerance, celiac disease and other useful resources.

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