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Coping with Food Allergies

Some of the most basic foods, such as bread, milk, soy or eggs, trigger allergic reactions in millions of people who are sensitive to them. These reactions can occur immediately after eating or hours or even days later and range from mild to severe. Some people break out in a rash or hives, some suffer grinding stomach aches and diarrhea or go to bed with a headache while some experience various other symptoms, from leg cramps to choking.

When a person is highly sensitive to a certain type of food, even the tiniest amount may cause a reaction, such as fumes, odor or microscopic pieces in the air. In fact, some people wheeze when they walk past the nut shop at the mall. If you have ever had a strong allergic reaction to any food, you know how serious a problem it can be. Most of the people who suffered life-threatening reactions to food had previously been warned by milder symptoms produced by the same foods. Yet not everyone takes the first signs seriously.

True food allergies are quite rare, occurring in about 2% of adults. A true allergic reaction is a misguided attack by the body’s immune system against a harmless substance. Such allergic reactions range from severe and sometimes even fatal anaphylaxis to milder forms of sensitivity and hypersensitivity. However, many forms of food-related problems do not involve the immune system but can be just as troubling. These can involve an intolerance or inability to digest certain foods or a specific response to a particular chemical or additive found in the food. In any case, you have to find out what is causing the adverse reaction and make sure it stays out of your diet.

Immediate reactions are typical of most true food allergies. They can start within seconds or up to two hours after eating the offending food. The most common offenders include peanuts, hazelnuts, walnuts, eggs and shellfish, such as lobster or shrimp. The especially severe reaction, called anaphylaxis, starts quickly from a few seconds after eating to fifteen minutes later, depending on how much food was ingested and how severe the person’s allergy is. Symptoms begin in areas where the food first comes into contact with your body. Your tongue and lips will swell and the inside of your mouth and throat will start to itch. Ignoring these warning signals is a big mistake, which can become fatal if not dealt with immediately since death may occur within two hours of exposure.

Delayed reactions usually occur more than twelve hours or even several days after eating the offending food, thus making the source of the problem difficult to identify. Typical symptoms include headache, bloating, mood swings, fatigue, lethargy, loss of concentration and possible skin reactions such as eczema. Foods most commonly causing delayed reactions include wheat, corn, dairy and all kinds of chemicals found in food. Delayed allergic reactions may not be true allergies but rather food intolerances. Some chronic conditions like irritable bowel syndrome, colitis, eczema, rheumatoid arthritis, migraine and certain psychiatric disorders are sometimes linked to this type of allergy or intolerance to specific foods.

Allergic Reactions to Related and non-Related Foods

You can have a negative reaction to one food and then sometime later experience a similar reaction to a different type of food. In fact, even very different foods from the same family share the same troublesome substances. Lectins in various types of legumes or gluten in three different types of grains are just some examples. The resemblance may not be obvious but your immune system will react as though the foods are the same. A person who is allergic to ragweed, for instance, may develop an itchy mouth after eating melons. Other related foods that you may not think of being related include pistachio nuts, cashew nuts and mango; apple, pear, and quince; spinach and beet; avocado, cinnamon, bay leaf and sassafras; allspice and guava; and rhubarb, buckwheat and sorrel.

Some people are also allergic to foods in unrelated food families. This condition is called coincidental allergy. One example of such combination are grains, legumes and citrus fruits. However, an allergy to milk is not necessarily accompanied by an allergy to beef or an allergy to eggs by one to chicken.

Food Intolerance and Reactions to Chemicals in Food

Some allergic reactions result from abnormalities of the digestive system. The best known is an inability to digest lactose in milk and dairy products due to deficiency of an enzyme lactase which breaks down lactose. Another common food intolerance involves the inability to digest the gluten in wheat and some other grains, such as rye and barley. Recent research suggests that gluten intolerance may be one of the culprits causing some physical and mental disorders, including schizophrenia. Studies have found that schizophrenia is uncommon in populations that eat little or no gluten and vice-versa, gluten intolerance is more common in schizophrenics than in normal population.

However, many allergic reactions are triggered by chemical substances found naturally in food or inserted as additives. One such example is caffeine. Some people become jittery or get a headache from drinking regular coffee but experience no such symptoms from the decaffeinated brew. The problem here is not the coffee itself but the caffeine. This common type of dietary disorder is called a pharmacologic reaction.

Some Offending Chemicals Found Naturally in Food

Histamine is commonly found in fermented cheese, dried sausage, wine, sardines, anchovies, mackerel, tuna, spinach, tomatoes and fermented foods such as sauerkraut. Possible reactions may include gastrointestinal distress, flushing and reddening of the skin, headache and itchy eyes. Histamines in food are a natural result of the action of non-disease-causing bacteria.

Serotonin can be found in plums, tomatoes, avocados and pineapple. It may induce headaches and nausea and raise blood pressure.

Methylxanthines, incl. caffeine and theobromine, are present in coffee, cocoa, chocolate, tea and cola drinks. They may cause stomach pain, diarrhea, headache, rapid heartbeats, restlessness, nervousness, insomnia, mood swings and concentration difficulties. Negative reactions to chocolate are more likely pharmacologic than allergic. The irritable feeling it provokes may be caused by a chemical called phenylethylamine whereas a true allergic reaction from chocolate is usually due to other ingredients in the candy, such as milk, hazelnuts or peanuts.

Tyramine can be found in wine and cheese, mostly hard cheeses. Tyramine induces symptoms like those of the methylxanthines.

Some Offending Additives in Food

Sulfites keep food looking fresh and hinder spoilage. They can be found as preservatives in dried fruits and dried potato products. Sulfites are sometimes sprayed on raw shrimp while they are still on the fishing vessel. They also commonly occur in wines, both naturally and as additives. The best-known source of sulfites in our diet is wine. Read the wine labels as some wines are also sulfite free. Ingesting foods or beverages that contains sulfites is known to cause mild to severe breathing difficulties in about 5% of the population with asthma. Other symptoms may include flushing, cough, weakness, faintness, turning blue and even a loss of consciousness and death. Non-asthmatics may also experience bad, though typically less severe reactions to the sulphites.

Monosodium glutamate – MSG is a naturally-occurring non-essential amino acid that is in the food industry used as an additive to enhance flavors in cooked foods. MSG may cause headaches and feeling of discomfort in some people. Although the Food and Drug Administration (FDA) recognizes MSG as a safe food additive, in Europe it is a subject to certain restrictions.

Benzoates are food preservatives that include benzoic acid, sodium benzoate, butylated hydroxytoluene and butylated hydroxyanisole. These substances can trigger severe asthmatic reactions and chronic skin problems. Benzoates occur in bread, fat, oil, margarine, potato powder, milk powder, instant drink powders, mayonnaise, jam, marmalade, chocolate, pickles, sauces, prawns, marinated fish and fruit juices.

Tartrazine, a synthetic lemon yellow dye also known as FD&C Yellow Dye #5, is widely used as a food coloring. Tartrazine can cause itching, hives, headaches and nasal congestion in sensitive individuals. This chemical is present in orange drinks, gingerbread, refrigerated rolls, pies, gelatins, instant puddings, butterscotch chips, hard candies, cake mixes, processed cheese and even in shampoo and toothpaste. Tartrazine must be listed on the product label.

Phenolphthalein. This chemical is related to tartrazine and it is derived from coal tar. Phenolphthalein is used to make candy pink. It can produce breathing difficulties, headaches as well as other symptoms.

When Does Food Allergy Start?

Adverse reactions to food can begin at any point in your life. Whether or not you develop food allergies depends on heredity, your immune system, ability to absorb nutrients in the intestine, the types of food you consume and the amount of a particular food you eat at one time. A child who has one allergic parent has roughly a 30-40% chance of developing allergy, twice as likely as a child with non-allergic parents. When both parents have allergies, the risk increases to about 40-60%. If both parents have the same kind of allergy, the likelihood rises to 60-80%.

Children happen to be far more susceptible to food allergies than adults. This is because the lining of their gastrointestinal tract is still immature, allowing substances to be more easily absorbed into the blood and trigger adverse reactions. For example, an allergy to milk, the most common food allergy in infants, often occurs in the first days of life. The good news is that about 80% of food allergies that begin in childhood are outgrown by the age of five. Most persistent are some of the more severe allergies, such as those to peanuts, hazelnuts, walnuts and other tree nuts, shellfish as well as other sea fish.

Diagnosing Food Allergies

Identifying the cause of food allergies can take a long time. The first thing your doctor will do is to take a comprehensive medical history and conducting a careful physical examination. The doctor will make sure that the source of your problems is not a disease before you start searching for foods that could be bothering you.

Certain symptoms you have had in the past are red flags to an allergist. These include runny nose, itchy eyes, rashes, scratching, a sense of choking as well as asthma-like symptoms. Atopic dermatitis, a form of eczema, or flushing under the skin are considered an indicator, especially in children. Abdominal pain, diarrhea, nausea and vomiting as well as low blood pressure may also suggest allergies. Because the tendency to allergy and hypersensitivity is often hereditary, your doctor will also need to learn about present or past symptoms in your close blood relatives.

Other than anaphylactic reactions to food, which tends to be immediate and consistent, symptoms of food sensitivities can vary not only from one person to another but from one day to another. The factors involved may, besides the type of food eaten, include its amount; how ripe it was; whether it was raw or cooked; what other foods you consumed at the same time; the status of your immune system; etc. In people with multiple hypersensitivities, a combination of events often precipitates the allergic reaction, such as eating a certain type of food shortly before or after cutting the grass.

Stress, exhaustion, lifestyle changes, lack of sleep and poor mental health also happen to be powerful factors affecting the likelihood of an offending food to impose physical symptoms. Other than anaphylaxis, symptoms of allergy can be easily confused with those of many other health conditions. Moreover, the source of a delayed reaction can be extremely difficult to identify, especially if the problem is caused by a combination of foods.

Diagnostic Tests

Physicians use several tests to confirm suspicions of specific food allergy. Though these tests are far from absolute, they can be helpful in determining a diagnosis.

Skin Tests

Skin test typically is the first test an allergist will perform. A few drops of a liquid extract of a food are placed on your arm. A needle is either gently drawn through the liquid along the top layer of skin (prick test) or scratched a little deeper into the skin (scratch test). If a red bump and surrounding rash emerges within twenty minutes, you have had a positive response. Skin tests tend to yield a high rate of false-positives. However, when the test is negative, you are highly unlikely to be allergic to that particular food. Skin tests are only about 30% accurate for diagnosing genuine food allergies, whereas for allergies to airborne particles, such as pollen, their accuracy is around 95%.

Blood Tests

Blood tests determine the presence of immunoglobulin E (IgE, the antibody that triggers food allergy symptoms) antibodies to suspected offending foods. In comparison with skin tests, the blood test is not affected by antihistamines and it is also suitable for people with extensive rashes that normally prevent them from using skin tests. Like skin tests, blood tests also provide a high percentage of false positives. Modern multi-allergen screening tests, which can measure over one hundred component allergens in a single blood sample, have recently replaced the total serum immunoglobulin E or IgE test, which was the original screening test for allergy.

Oral Food Challenges

Open Challenge. If skin tests and blood tests were negative, you may be asked to swallow capsules containing a small amount of the suspected food or eat it in some other form. If you can eat increasing amounts up to a normal portion without any adverse reaction, the food is probably safe for you. This test must be done in the doctor’s presence. Open challenge can also be used to confirm a positive skin test or blood test.

Closed Challenge. In this test you are given unmarked foods to eat, as the doctor watches for a reaction. This method is done as a double-blind test, which means that neither you nor the person handing over the capsule or other form of disguised food, knows its contents.

Elimination Diet. In this test you will temporarily remove offending foods from your diet and then cautiously reintroduce them, one at a time. If symptoms disappear in a food’s absence and then reappear in its presence, you have probably found the cause. Do not attempt an elimination diet without a doctor’s supervision if you have asthma, diabetes, heart disease, Crohn’s disease or any other serious chronic condition. For children, the entire procedure should be overseen by an allergist.

Treating Food Allergy

The best way to treat adverse food reactions is prevention, i.e. by avoiding the offending food. When that is not possible because the cause has not yet been diagnosed, certain symptoms can at least be improved with the help of medications.

Drugs Used to Treat Symptoms of Food Allergy

Drugs cannot remove the food allergy but they can relieve some of its symptoms. Still, prescription medications can be extremely helpful.

  • Antihistamines. For runny nose, watery eyes, sneezing, itchy skin or hives, the allergist may prescribe an antihistamine such as desloratadine (Clarinex, Aerius), hydroxyzine (Vistaril, Atarax), rupatadine (Rupafin, Alergoliber), carbinoxamine (Palgic), levocetirizine (Xyzal), fexofenadine (Allegra), loratadine (Claritin, Alavert), diphenhydramine (Benadryl) or cetirizine (Zyrtec). However, these medications are not strong enough to counteract an anaphylactic reaction.
  • Nasal sprays. Cromolyn (Nasalcrom) known as a mast cell stabilizer, certain steroids such as beclometasone (Beconase, Vancenase), fluticasone (Flonase), mometasone (Nasonex) and triamcinolone (Nasacort) as well as nasal applications of some antihistamines such as azelastine (Astelin, Astepro) discourage release of irritating histamines and the slow-reacting substance of anaphylaxis (SRS-A).
  • Decongestants, like those used to ease cold symptoms, can reduce congestion and swelling.
  • Bronchodilators in oral or aerosol form relieve breathing by opening air passages in the lungs. This is particularly important for asthma sufferers who experience bronchospasms. Examples include metaproterenol (Alupent), lbuterol (Proventil), pirbuterol (Maxair) and levalbuterol (Xopenex HFA).
  • Steroid creams such as hydrocortisone (Cortaid) can relieve itching.

Side effects of these medications are not too common but they may include dry mouth, frequent or painful urination, drowsiness, nausea, vomiting, anxiety, loss of appetite, sleepiness, stomach pain, constipation or diarrhea and headaches. Second and third generation antihistamines are much less likely than older ones to dry out the mouth and nasal passages and cause sleepiness.


In sublingual immunotherapy, small amounts of the allergenic food are placed under the tongue. The idea is to immunize the body against the food. This method could be dangerous if you were to have a strong allergic reaction during the treatment. Sublingual immunotherapy is not approved in the US (though it is accepted in Europe, Asia and South America) and thus its usage in the US is off-label. Allergy shots are yet another form of immunotherapy but they are not used to treat food allergies.

Where to Find Related Information:
College of Allergy, Asthma and Immunology
Kids with Food Allergies