Some of the most basic and wholesome foods—milk, eggs, or bread—can have very unwholesome effects if you are one of the millions of people who are painfully sensitive to them. Immediately after eating—or hours or even days later—you may break out in a rash or hives (itchy, red, raised patches of skin), have grinding stomach aches and diarrhea, go to bed with a headache, or experience any number of other symptoms, from leg cramps to choking. While many foods can cause reactions ranging from mild to severe, some are much more common culprits than others (see the “Common Offenders” box nearby).
Most people just don’t recognize or understand the dangers. Tell a food server in a restaurant that you can’t eat peanuts, and you may be served a dish cooked in a pan that held another customer’s peanut-laden meal—a potentially lethal mistake for a person with a peanut allergy. Tell a friend who’s making you dinner that lobster is a no-no, and you may find it has been used anyway in preparing a sauce. They aren’t trying to hurt you, they just can’t imagine it making a difference.
When a person is highly sensitive to a type of food, even the tiniest amount may trigger a reaction; for example, as little as one 5,000th of a teaspoon of peanut, according to the Food Allergy Network, a respected consumer information group. In fact, some people even feel mild symptoms come on if they touch such a food or enter a room where it’s being prepared. The odor, fumes, or microscopic pieces in the air will do it. “Some people wheeze when they walk past the nut store at the mall,” notes Dr. Jeffrey Factor, an allergist in West Hartford, Connecticut.
Anyone who has ever had a strong allergic reaction to food knows just how serious a problem it can be. Yet not everyone takes the necessary precautions to prevent it from happening again or to handle it when it does. You should know that most of the people who experience life-threatening reactions to food have previously been “warned” by milder symptoms produced by the same foods.
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True food allergies are rare, occurring in only about 1 or 2 percent of adults. It’s also unusual for an individual to be allergic to more than one or two foods. Allergic reactions range from severe and even fatal anaphylaxis to milder forms of sensitivity and hypersensitivity. A true allergic reaction is a misdirected attack by the body’s immune system against an ordinarily harmless substance.
Other forms of food-related discomfort don’t involve the immune system, but can be just as real and troubling. Some involve an intolerance or inability to digest certain foods. Others are a response to a specific chemical or additive found in the food, much like the side effect of a medication.
Whether the problem is an allergy, an intolerance, or a chemical side effect, the bottom line is the same. You need to find out what’s causing the reaction and make sure it stays out of your diet.
When the Immune System Goes on the Attack Mast cells containing granules or small "packages" of chemicals, are located throughout the body tissue, especially near the lung, nose, and stomach. Clinging to the outside membrane of each mast cell are up to 100,000 immunoglobulin E (IgE) molecules of various kinds, that can respond to individual foreign substances called antigens.When an antigen traveling through the blood comes into contact with a type of white blood cell called a plasma cell, the plasma cell produces an antibody to fight the antigen. These antibodies begin to flow through the bloodstream. As soon as they touch at least two "receptor" IgE molecules on a mast cell, the cell explosively degranulates (discharges granules) into the bloodstream. There, the granules break open, releasing histamine and other substances (mediators) meant to attack the antigen. A flood of these substances can simultaneously cause adverse reactions in the body. Other white blood cells (basophils), which travel through the blood, respond similarly to antibodies by spraying histamine and serotonin at them.When an ordinarily harmless foreign substance such as food comes to be viewed as an antigen by the body, it's considered an allergen, the cause of an allergic reaction. |
What Happens During an Allergic Reaction
A real allergic reaction is a case of mistaken identity. The body’s immune system identifies a protein or related substance in the offending food as the enemy and sends out a battalion of defenses to destroy it, just as it would attack a virus or bacteria. In both types, the immune system also marshals overeager soldiers called histamines, which produce painful sensations in the skin, eyes, and throat (see box, “When the Immune System Goes on the Attack”).
The entry of an allergen, (any substance that causes an allergic reaction), into the body of a susceptible person triggers a chain of events in the immune system. In one type, called humoral allergy, antibodies are created after one exposure to the food in order to fight the “invaders” next time. These antibodies are called immunoglobulin E (IgE) and can usually be identified by a blood test (see the section on diagnosis, later in the chapter). In another type of reaction, cellular allergy, immune cells called lymphocytes become sensitized over time by exposure to certain chemicals and proteins in food. When next they meet, the lymphocytes overreact, expelling the foreign material just as they would reject an organ transplant.
The effects of exposure to a food allergen range from a little tingling in the mouth or swelling and redness of the skin to life-threatening difficulties. Symptoms may include difficulty breathing, hives, vomiting, and diarrhea (see box on “Typical Symptoms of True Food Allergy”). In many children, the first red flag is eczema, a rash that may appear anywhere on the body, especially the cheeks and buttocks (often severe in infants).
Typical Symptoms of True Food Allergy | ||
| The first signs of an immediate allergic reaction may be itching and swelling in your mouth. This may be followed by progressive difficulty breathing, with coughing, wheezing, chest tightness, and a feeling that your throat is closing up. The worst reactions end in anaphylaxis (see accompanying box). |  | |
Immediate Reactions
Immediate reactions, typical of most true food allergies, are dramatic and can start within seconds or up to two hours after eating. Routinely implicated are peanuts, tree nuts such as walnuts, eggs (especially the whites), and shellfish with outer skeletons, such as shrimp and lobster.
The especially severe reactions called anaphylaxis start quickly, from a second after eating the offending food to 15 minutes later, depending on how severe the person’s allergy is and how much food was ingested (see the “Signs That Spell Emergency” box). Logically enough, symptoms begin where the food first comes into contact with your body. Your lips and tongue will swell, the inside of your mouth will start to itch, and you may feel a sense of impending doom. Something is telling you to get help. Ignoring that extremely useful warning is a big mistake, and can be a fatal one since death can occur within two hours of exposure. Fortunately, of the 1,000 or so Americans who go into anaphylactic shock each year, all but about half a dozen survive.
Here’s a standard scenario. George munches a shrimp cocktail at a party. The inside of his mouth itches, but he hardly notices it and makes no connection with the food. Not long afterward, he cooks a shrimp dish. His lips tingle and he develops a rash. Now is the crucial time for him to see a doctor and learn about his allergy, but it doesn’t occur to him. A month later, one spoonful of shrimp bisque at a restaurant makes him gasp for air and nearly collapse as painful hives pop up all over his body. Fortunately, the restaurant proprietors know what to do. In the hospital emergency room, George is told never to eat shrimp again.
Delayed Reactions
Delayed reactions, such as headache, lethargy, mood swings, loss of concentration, possible skin involvement—may not appear for a day or even longer, making the source of the problem difficult to diagnose. In one sort of delayed reaction, symptoms begin 12 hours after the food is eaten and peak in 24 to 48 hours. A more protracted type doesn’t produce symptoms for 18 to 24 hours; they’re most severe in 72 hours. Foods typically causing delayed reactions, which may not be true allergies, include dairy, wheat, corn, and all kinds of chemicals (although some people may have immediate reactions from ingesting them). Some scientific studies suggest that chronic conditions like irritable bowel syndrome, colitis, rheumatoid arthritis, and certain psychiatric disorders may be caused—at least in some people—by delayed allergic reactions to specific foods, or by food intolerances. While the evidence is by no means conclusive, this possibility is worth considering when trying to figure out the best course of treatment to pursue.
Cross-Reactivity: When a Reaction “Runs in the Family” … of Foods
You could very easily have a reaction to one food, and then sometime later have a reaction to a different food. You might think there is no connection. But even very different foods from the same family share the same troublesome substances. Lectins in various types of legumes, are one example. The resemblance isn’t always obvious—except to your immune system, which responds as though the foods are the same. A person who is allergic to ragweed, for example, might develop an itchy mouth after eating melons.
One nurse who constantly wore latex gloves (made from the rubber tree) had a life-threatening reaction to chestnuts after ignoring a previous mild reaction to the gloves. (She might also have reacted badly to avocado or banana, which grow on related tropical trees.) Fortunately, she recovered.
Dietitians and allergists can explain which “plant cousins” might affect your hypersensitivities. Books on allergy also provide such lists. Related foods that you might not think of include apple, pear, and quince; beet and spinach; buckwheat, rhubarb, and sorrel; cashew nuts, pistachio nuts, and mango; avocado, bay leaf, cinnamon, and sassafras; and allspice and guava.
People who are allergic to foods in unrelated food families have coincidental allergies. Some such combinations are more common than others—grains, citrus fruits, and legumes, are one example. An allergy to eggs, however, isn’t necessarily accompanied by an allergy to chicken, or a milk allergy by one to beef.
Signs That Spell Emergency: Anaphylaxis  The most dangerous form of allergic reaction is anaphylaxis, literally "without protection." Without fast treatment, the throat swells enough to close off the airway, leading to suffocation. Meanwhile, blood pressure falls until the person goes into shock. Foods that cause anaphylactic reactions most often are peanuts and peanut products such as peanut butter; tree nuts; shellfish, especially shrimp and crab; and other fish. Other reported incidents have involved milk, soybeans, wheat, barley, rice, corn, potatoes, spinach, bananas, melons, tomatoes, citrus fruits, and chocolate. Any severe food allergy could trigger the condition. People with asthma are at greatest risk.Anaphylaxis can also result from insect stings or from aspirin and a few other medications, especially penicillin. In rare cases, someone goes into anaphylactic shock while doing strenuous aerobic exercise such as running (exercise-induced anaphylaxis). The exercise-induced attacks are prompted by foods that prove allergenic only when combined with exercise. When primed by these foods, the blood vessels' natural response to physical activity triggers mast cells into releasing their potent inflammatory chemicals.Anyone who has ever experienced an anaphylactic reaction should always carry a preloaded syringe of epinephrine (adrenaline). Popular brands include EpiPen (one dose) and Ana-Kit (multiple-dose package). You should also wear a special bracelet that describes the problem and provides a doctor's name and phone number. If you should become unconscious, people will know what's wrong and what to do. Bracelets can be purchased from Medic Alert. Call 1-800-432-5378 or visit www.medicalert.org.Any combination of the symptoms listed here, particularly during or soon after a meal, suggests an anaphylactic reaction to food. (The symptoms are the same whatever the cause, but food causes more anaphylactic deaths per year than insect stings.) If epinephrine is not available, and the person is conscious, administering a liquid antihistamine is better than nothing. Then rush the victim to the nearest emergency room. Do not let him or her leave the room alone and do not "wait to see what happens." Seconds count. |
It is all too common for people with stomachaches, headaches, or other complaints for which their doctors couldn’t find an underlying disease or condition to be told, “It’s all in your head.” Sometimes that may be true. But, in millions of cases, the problem may be an unrecognized non-allergic reaction to one or more specific kinds of food or components of food. Anyone with physical problems that might be related to food should explore that route. Numerous books on the subject by physicians and other health practitioners are studded with convincing case histories of patients of all ages who found relief from longtime and/or severe symptoms only after learning which foods to avoid.
The Elusive Reactions: Intolerance and Chemical Side Effects
Some of these hard-to-pin-down problems result from abnormalities of the digestive system. The best known, an inability to digest milk and dairy products due to an enzyme deficiency, is explained in detail in the box on “Lactose Intolerance.”
Another, involving the inability to digest the gluten in wheat and some other types of grain, is discussed in “Dealing with Digestive Disorders.” Some researchers believe that gluten intolerance may be one of the culprits behind a variety of physical and mental disorders, including schizophrenia. Surveys have found, for instance, that schizophrenia is very uncommon in populations that eat little or no gluten, when compared to those that ingest lots of gluten-laden grains. Additional evidence comes from clinical trials in which gluten was removed from the diets of psychotic patients. Of six controlled experiments, three found that eliminating gluten significantly improved symptoms, suggesting that the treatment may work for at least some patients, though certainly not all. In a seventh trial conducted among 24 chronic schizophrenics, two patients improved dramatically, showing less excitability, perceptual disorganization, depression, and grandiose thinking.
Many problems, however, are triggered not by digestion, but by chemicals found naturally in food or inserted as additives. These substances can produce side effects resembling those of a drug. An example is caffeine. When someone who becomes jittery and anxious or gets a headache from drinking regular coffee finds he has no symptoms from the decaffeinated brew, the problem isn’t with the coffee itself, it is with the caffeine. This common type of dietary problem is called a pharmacologic reaction.
Among the Offending Chemicals Found Naturally in Food:
Serotonin, found in tomatoes, plums, avocados, and pineapple. It can cause headaches and nausea and can raise blood pressure. Histamine is found in Swiss and other fermented cheeses, wine, dried sausage, anchovies, sardines, tomatoes, spinach, tuna and mackerel that weren’t sufficiently chilled before canning or cooking, and fermented foods such as sauerkraut. Reactions include gastrointestinal distress, headache, flushing and reddening of the skin, and itchy eyes. Histamines are formed naturally in food by the action of non-disease-causing bacteria.
Methylxanthines, including caffeine and theobromine, are found in coffee, tea, cola drinks, chocolate, and cocoa. They may induce headache, stomach pain, diarrhea, nervousness, rapid heartbeats, restlessness, insomnia, mood swings, and an inability to concentrate.
Some people’s reaction to chocolate is more likely pharmacologic than allergic. Chocolate is, in fact, “one of the most misunderstood foods,” and true allergy to it is extremely rare, says Dr. Jerry Shier, an allergist and immunologist in Silver Spring, Maryland. The jittery, irritable feeling it provokes may result from a chemical in chocolate called phenylethylamine. If a true allergic reaction strikes, says Dr. Shier, it’s likely to be the fault of other ingredients in the candy, such as milk, peanuts, or various nuts from trees.
Tyramine is found in wine and cheeses, especially hard cheeses such as Stilton, blue cheese, and aged cheddar. It produces symptoms like those of the methylxanthines.
Lactose Intolerance: Not Quite an Allergy Many people assume they're allergic to milk because whenever they drink it or eat ice cream, cheese, or other dairy products, they have gassy stomach pain, bloating, and diarrhea. Some of those people are indeed allergic to milk, as an allergist can discover, and they should avoid it. But others have a digestive problem called lactose intolerance.What they have is not an allergy but the most common form of enzyme deficiency. The missing or insufficient intestinal enzyme is lactase, which is needed to break down the natural sugar in dairy foods (lactose) into smaller parts to complete the process of digestion.When people with lactose intolerance drink milk or eat a dairy product, the lactose remains in the intestines, where it is prey to natural bacteria. The resulting bubbly fermentation causes gas and diarrhea, usually starting from 15 minutes to several hours after eating. (To those symptoms, someone with a true milk allergy might add nasal congestion, headache, frequent urination, and hives.)Lactose intolerance is far more common among some ethnic groups than others. According to the National Center for Nutrition and Dietetics of the American Dietetic Association, the condition is found in about 80 percent of Asians and Native Americans, 75 percent of blacks, 50 percent of Hispanics, and 20 percent of whites.DiagnosisConsidering the symptoms, it's easy to see why lactose intolerance can be misdiagnosed as an ulcer, irritable bowel syndrome, or some other gastrointestinal disorder. Taking a lactose intolerance test can determine whether lactase deficiency is causing your problem. In the doctor's office, you're given 50 grams of lactose to drink. Lactose intolerance is diagnosed if diarrhea, abdominal bloating, and discomfort result within 20 to 30 minutes, and if blood tests demonstrate little or no sugar has reached your blood.If even that is uncertain, the diagnosis can be confirmed without question if little or no lactase is found in a laboratory analysis (biopsy) of a small piece of tissue taken surgically from the jejunum, which is part of the small intestine.A safe, inexpensive, and fairly reliable way to diagnose the problem is with the hydrogen breath test. After being given a certain amount of milk to drink on an empty stomach, you'll breathe into a device that traps and measures exhaled air at timed intervals. If your small intestine fails to break down the lactose from the milk, excess carbohydrates will reach your colon and undergo fermentation by bacteria there. This will increase the level of hydrogen in your blood and in your exhalations.With your doctor's permission (to make sure you won't be triggering a serious milk allergy) you can test yourself at home. Avoid all dairy products for two weeks. If formerly frequent pains fade away, you may be on the right track. Now drink a glass of milk. If the pains come back, lactose intolerance may be the culprit. If you have no such reaction for a few days, eat some dairy products and drink a little more milk until you're eating a fair amount at one time. If no symptoms appear, the problem probably lies elsewhere. |
Some Common Additives, Which Include Preservatives, Flavorings, and Colorings:
MSG. Monosodium glutamate, used to enhance flavors in cooking, and in prepared foods, causes headaches and other symptoms in some people. Studies are inconclusive about its effects, and the Food and Drug Administration (FDA) has placed no restriction on its use. If MSG seems to affect you, don’t patronize restaurants that use it.
How to Tolerate Lactose Intolerance |
| A milk product called Lactaid is available in the milk section of many supermarkets. Another way to cope is to swallow lactase tablets before eating dairy products or to add lactase drops to milk before drinking it. Depending on the extent of your reaction, you may be able to eat dairy products that are low in lactose, including cheddar and other hard cheeses. Plain (not flavored or frozen) yogurt that contains active cultures may work for you, too.If you have to avoid all milk products, your doctor will advise you to take calcium tablets, since milk is a major source of that important mineral. Eat heartily from the large group of nondairy calcium-rich foods, such as broccoli; dark green, leafy vegetables, such as collard greens, kale, and spinach; legumes, including soybeans, peanuts, and beans (assuming they agree with you); sesame seeds; and certain oily fish, such as salmon and sardines, especially the canned kind containing edible bones.When shopping, watch for these words on food labels, all of which indicate dairy: the obvious, such as milk, cream, butter and most margarines; and the less obvious, including nonfat milk solids, lactose, casein (which represents 80 percent of the protein of cow's milk), sodium caseinate, and whey (20 percent of the protein in cow's milk).For a meal out, try an Asian restaurant such as Chinese, Japanese, Korean, or Thai. Not surprisingly, milk is not a staple of these cuisines, which were developed by people with a very high rate of lactose intolerance. |
Sulfites keep food looking fresh and retard spoilage. They’re used on dried fruits and dried potato products such as mashed potato flakes. Sulfites are sometimes sprayed on raw shrimp while they’re still on the boat. A rash of bad experiences at salad bars, including deaths, led the FDA to clamp down about 10 years ago, forbidding sulfite spray on fresh fruits and vegetables sold or served raw. In addition, sulfites must be included on the ingredient list when used as preservatives in packaged or processed foods.
Eating anything that contains sulfites causes mild to severe breathing difficulties in about 5 percent of people with asthma, or over a million Americans, according to the Center for Science in the Public Interest, an advocacy and research group in Washington, D.C. Sulfite symptoms include flushing, faintness, weakness, cough, and turning blue—as well as loss of consciousness and death. Nonasthmatics may also have bad, though typically less severe reactions to the chemical as well. The reason isn’t clear, but may be metabolic: a deficiency of sulfite oxidase, the enzyme that breaks down sulfites in the body. If you think sulfites may make you feel unwell, avoid foods that contain sodium sulfite, sulfur dioxide, or sodium or potassium bisulfite or metabisulfite.
The best-known source of sulfites in food is wine (see the box on “Complex Effects of Wine”). Some wine labels now declare their bottles’ contents to be sulfite free, and people with mild adverse reactions to sulfites might try those.
Benzoates. These preservatives include benzoic acid, sodium benzoate, BHA (butylated hydroxyanisole), and BHT (butylated hydroxytoluene). The benzoates can cause chronic skin problems and severe asthmatic reactions in adults. They’re found in bread, milk powder, potato powder, fat, oil, margarine, mayonnaise, jam, chocolate, soft drinks, and instant drink powders.
Complex Effects of Wine Plain wine constitutes a cocktail of natural drugs. Tyramine can induce symptoms like those of caffeine: headache, stomach ache, anxiety, and rapid heartbeats. Nearly all wines contain sulfites,used to stop the fermentation process and stabilize the wine. Some brands have been advertising their freedom from that chemical on the label. Molds and yeasts trigger many allergic reactions. Red wines in particular also contain histamines, the major chemical mediator responsible for allergic symptoms, including migraine attacks. Other possible ingredients are sulfur dioxide and egg white.Champagne processing starts with a mixture of different grapes, any of which might provoke a reaction in susceptible people. Techniques for aging and fermenting wines vary from one vineyard to another and are traditionally kept secret. You may find that only certain types, nationalities, brands, or even years of wine bother you; take note and avoid them. Newer vintages may give you more headaches than older ones. And like any form of alcohol, wine can increase the risk of developing an immune allergic reaction to other foods. |
FD&C Yellow Dye #5 (tartrazine), a widely used food coloring, induces itching, hives, nasal congestion, and/or headaches in sensitive individuals. The best proof is the label rather than the food itself, which could be any of a variety of colors; green, orange, purple, or another mixed color. Read the labels of orange drinks, pies, gingerbread, butterscotch chips, instant puddings, gelatins, hard candies, cake mixes, processed cheese, refrigerated rolls, and even shampoo and toothpaste.
Phenolphthalein. Related to tartrazine and derived from coal tar, this chemical is used to make candy pink. It can produce headaches, breathing difficulties, and other physical problems.
When Food Allergy Starts
Allergies and other adverse food reactions can begin at any time in your life. Whether or not you develop food allergies depends on heredity, your ability to absorb nutrients in the intestine, your immune response, the types of food you eat, and the amount of a particular food that you eat at one time.
Any tendency you may have towards allergies is with you from birth. A child who has one allergic parent has roughly a 30 to 40 percent chance of developing some kind of allergy, twice as likely as a child with nonallergic parents. If both parents have allergies, the risk is about four times as great (40 to 60 percent). When both parents have the same allergy, the likelihood rises to 60 to 80 percent.
People who are born with a general vulnerability to allergies usually have their first reactions early. For instance, an allergy to milk, the most common allergic problem in infants, often appears in the first days of life.
In any case, children are far more susceptible to food allergies than adults. The lining of their gastrointestinal tract is still immature, allowing substances to more easily stream out into the blood and trigger reactions. Some 2 to 5 percent of children in the United States have confirmed food allergies. The proportion with an intolerance or chemical sensitivity is a great deal higher. Fortunately, at least 80 percent of food allergies that begin in childhood are outgrown by the age of 5. Most persistent are some of the fiercest allergies: to peanuts, tree nuts, shellfish, and other fish.
Minimizing Allergic Reactions in Your Baby There is nothing you can do to prevent allergies in infants, but there are ways to minimize the risk of an allergic reaction. If your family has a history of food allergies, and you plan to breastfeed, you may be advised not to eat the foods that are most likely to upset your baby's digestive system, particularly milk and wheat.There's now also reason to believe that peanut protein and peanut-derived allergens can be passed along to the baby during breastfeeding. When researchers analyzed breast milk samples from 23 healthy volunteers who had eaten 50 grams of dry roasted peanuts, peanut protein was found in the milk of 10 of the women within two hours, and was detected in the milk of an eleventh woman after six hours. The investigators also discovered Ara h1 and Ara h2, two of the major peanut allergens. These findings could explain why some children have a severe allergic attack the first time they eat peanuts, even though such immune reactions usually occur only after a second exposure to the allergen. It's possible that many of these children were initially exposed while they were nursing.Waiting until your baby is six months old before starting solid foods can also delay the baby's direct exposure to possible allergens. If you are bottlefeeding and your baby has a reaction to cow's milk-based formulas, you should know that there are soy-based formulas and other substitutes as well. (A child with an allergic older sibling has about a 25 to 35 percent chance of being allergic as well.)You may be given similar advice if your baby is colicky. Colic is generally defined as inconsolable crying for more than 3 hours a day, more than 3 days a week, for 3 or more weeks. Providing additional feedings—a time-honored way to soothe a cranky baby—only intensifies the problem if it happens to be related to food (not always the case). Such babies are crying because their stomachs hurt.You should consult your pediatrician or family doctor before you make any changes on your own in your baby's diet, to make sure that both of you remain well nourished. If milk is abandoned, calcium supplements will be needed. |
Your First Move: Seeing a Doctor
Identifying and dealing with food allergies, especially when their cause is far from obvious, can take a long time. You might explore the subject with your family doctor. If you aren’t getting anywhere, consider consulting an allergist. These specialists need several years of additional training after medical school to obtain board certification in allergy and immunology. To find an allergist near you, call the nearest large medical center or hospital affiliated with a medical school.
The first thing your doctor will do is take a comprehensive medical history, followed by a careful physical examination. You want to be sure that the source of your problems isn’t a disease before you and your doctor begin searching for foods that could be bothering you.
Certain symptoms you’ve had at any time, even in infancy, are red flags to an allergist. These include rashes, scratching, runny nose, itchy eyes, a sense of choking, and asthma-like symptoms, even if you’ve never had asthma. Atopic dermatitis, a form of eczema (skin rash), is considered a telltale sign, especially in children. So is flushing under the skin. Abdominal pain, nausea and vomiting, diarrhea, and low blood pressure may also suggest allergies.
Because the tendency to allergy and hypersensitivity is so closely related to heredity, your doctor will want to know as much as possible about present or past symptoms in your close blood relatives. Find out what you can before your appointment.
Why Diagnosis Is Difficult
Other than anaphylactic reactions to food, which are swift and consistent, symptoms from unwelcome foods can vary not only from one person to another but from one day to another. Depending on the individual, the many factors involved (besides the type of food eaten) include its amount; how ripe it was (tomatoes, for example, become increasingly likely to cause a reaction as they ripen); whether it was raw or cooked, and how it was cooked; what other foods you ate at the same time; the status of your immune system; and other triggering factors such as whether you were sitting in a room full of smoke or perfume.
In people with multiple hypersensitivities, it’s often a combination of events that precipitates the reaction, such as eating a candy bar before cutting the grass, then devouring a tub of movie popcorn swimming in additive-laden fake butter. Some people do better in summer than in winter.
Stress also affects the power of an offending food to impose physical symptoms. And hypersensitivities can appear or disappear suddenly, without any apparent reason. Other than anaphylaxis, symptoms of allergy can be confused with those of many other conditions—peptic ulcer, hiatal hernia, arthritis, thyroid deficiency, sinus infections, and exhaustion. Furthermore, while an immediate reaction to a food usually leaves no question of its cause, the source of a delayed reaction is extremely hard to identify, especially if the problem is a combination of foods. Tests may fail to pin-point any of the foods. No wonder many doctors (and patients) are skeptical or give up.
In addition, doctors who don’t happen to have a special interest in allergy may not even think of food as the culprit unless you suggest the possibility yourself. Medical schools have always given short shrift to all aspects of nutrition, food allergy included. While that may be changing in some places, many doctors still belittle or ignore the potentially significant role of food in their patients’ ill health.
Compounding the problem is doctors’ justifiably low opinion of individuals and organizations that capitalize on people’s pain and confusion. Some such practitioners and groups may be downright unscrupulous, while others well-meaningly offer unproved tests, products, and services for high fees. Physicians have been trained to reject any scientifically unsound practice.
The Diagnosis: Tests You Can Try
The most important goal is to learn whether you have a food allergy in the first place. You don’t want to ban a food without good reason. But because food allergies come in such variety—multiple, cumulative, delayed—you’ll have to proceed slowly.
Allergists use several tests to confirm suspicions of specific food allergy. These tests are far from absolute but can be helpful in making a diagnosis.
Skin Tests
In these tests, the doctor places a few drops of a commercially prepared liquid extract of a food on your back or 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 (wheal and flare reaction) appears after about 10 to 20 minutes, you’ve had a positive response. That food can then be checked into further.
Skin tests provide a high rate of false-positives, in which the result says you are allergic but you’re really not. When the test is negative, however, you are highly unlikely to be allergic to the food. Skin tests work about 30 percent of the time for genuine food allergies; for allergies to airborne particles, such as pollen, they are about 95 percent accurate.
Although your regular internist or family practitioner may be able to provide good advice about your reactions to food, have any skin testing done by a board-certified allergist, suggests Dr. Martha V. White, director of research at the Institute for Asthma and Allergy, Washington Hospital Center, Washington, D.C. Such specialists are trained to know the difference between a true-positive result and a false-positive one induced by hives or strongly reactive skin. They’re aware of reasons your skin might not respond to the test; for example, if you’re taking an antihistamine. Most important, they’re best equipped to handle the rare case of a bad reaction, such as shock.
Blood Tests
In the radioallergosorbent (RAST) test, done in a laboratory, a small sample of serum (the liquid part of blood) is mixed with a food extract in a glass dish. If the white blood cells release a large amount of IgE antibodies in an effort to fight the intruder, you’re supposedly allergic to that food. The problem with RAST tests is that they cost two or three times as much as skin tests, take much longer, and are not as reliable. You may also hear about another blood test called the enzyme-linked immunosorbent assay (ELISA). It is a respectable test but has a comparably poor accuracy record for detecting allergies.
Open Challenge
After a negative skin test result, indicating that you’re not likely to have a severe reaction to a suspected food, you’ll swallow capsules containing a small amount of the food, or eat it in another form, and then see what happens. If you can eat increasing amounts, up to a normal portion, with no reaction, the food is probably safe for you. This is done in the doctor’s presence. Open challenge is also used to confirm a positive skin test—provided your allergic sensitivity isn’t severe.
Closed Challenge
In this procedure you are given unmarked foods to eat, disguised by being freeze-dried and placed in an opaque capsule or stirred into another mixture, as the doctor watches for a reaction. This method is considered foolproof, especially if done as a double-blind test—the procedure used in the best scientific studies. Double-blinding means that neither you nor the person handing over the pill (or other form of disguised food) knows its contents, which were previously coded by someone else. Preconceptions therefore can’t color the outcome for either of you. For young children, small amounts of suspected allergenic food are hidden in foods they can tolerate.
Challenges are done in the doctor’s office. If your doctor believes that the food being tested could provoke a severe reaction, however, the site may be a hospital emergency room—just in case. The greater the likelihood of a life-threatening reaction, the less likely it is that a challenge will be risked.
The Elimination Diet
One good way to identify allergens is an elimination diet. You’ll temporarily remove offending foods from your system, then cautiously reintroduce them in pure form (without additives) one at a time. If symptoms disappear in a food’s absence, then return in its presence, you have probably found your problem. Follow-up testing can help make sure.
In a general elimination diet, the most common allergens (and your favorite foods) are removed for as long as it takes to clear out your system. Instead, you’ll eat foods that you don’t consume regularly, perhaps lamb, rice, and pears, and that are therefore unlikely to have caused your symptoms. You may be asked to temporarily stop taking vitamin and mineral supplements and even prescription drugs, (with the prescribing doctor’s permission) in case a pharmacologic reaction is involved. Heavy coffee or tea drinkers are advised to wean themselves gradually before starting the diet, to prevent uncomfortable symptoms of caffeine withdrawal.
Some doctors advise cleansing the system with a five-day fast, eating or drinking nothing but distilled water. However, this is very difficult—even dangerous—and is not generally recommended. Most people follow a specific diet written out for them by an experienced health professional. Having a doctor or dietitian oversee your plan will keep your diet balanced and healthy. And no cheating, or it’s back to square one.
Before you change your menu, you’ll keep a food diary. Each day, you’ll write down every bite you eat, when you felt symptoms, how long they lasted, and how intense they were, on a consistent scale (such as 1, mild; 2, moderate; 3, severe). You’ll list any other precipitating factors, such as stress, as they occur.
Avoiding an offending food for a while permits your body to “calm down” so that consuming a small or even a moderate amount later may have no ill effects. Eating large quantities of the offending food again, however, is likely to rekindle the hypersensitivity. The best route is moderation.
If eating a certain food makes you feel a little bit sick, but you can’t imagine life without it, stop eating it for at least three months, or in extreme cases for a couple of years. Then eat a small amount no more than once or twice a week and see if the situation has improved. Note: This strategy may help with pharmacologic reactions and intolerance, but won’t work with a true allergy. In fact, if you’re truly allergic, symptoms upon suddenly reintroducing the food could be dangerous. Any food that has ever caused symptoms of early anaphylactic shock must be avoided for life. To be sure, consult a physician.
Don’t attempt an elimination diet without a doctor’s supervision if you have asthma, heart disease, diabetes, Crohn’s disease (a bowel disorder), or any other serious chronic condition. For children, the entire procedure should be overseen by an allergist since a poorly designed diet could lead to severe nutritional deficiencies.
The Diagnosis: Tests to Avoid
Cytotoxic testing. This lab test has fallen into disrepute for its notorious lack of accuracy. It works like this: a small amount of blood is placed in a glass dish and a food extract is added. The sample is not checked for IgE, as in a blood test. Instead it’s studied for a strong reaction in the white blood cells. The variables are so many and the rate of accuracy is so low—with the test either identifying a harmless food as harmful or vice versa—that this method is now generally considered useless.
Is Sugar-Induced Hyperactivity Just Hype? About 20 years ago, many parents of hyperactive children eagerly accepted a physician's hypothesis that what made their kids bounce off the walls was sugar and the chemical flavorings and colors added to food. Since then, a number of studies have essentially debunked that proposition. Nevertheless, some families have insisted that removing those items from the children's diets improved their behavior.Many pediatricians dismiss the idea. Others believe as strongly that children's antisocial, even bizarre and sometimes self-destructive behavior often stems from food hypersensitivity. There is at least some scientific evidence to support this contention. As far back as 1985, researchers found that giving hyperactive children an "oligoantigenic" diet improved their behavior and also helped relieve headaches, abdominal pain, and seizures.An oligoantigenic regimen eliminates the most common allergens, including wheat, milk, soy, corn, and peanuts. In the 1985 study, once the children had improved, the suspected allergens were secretly re-introduced into their diet—one at a time—and sure enough, symptoms began to reemerge, proving that certain foods were in fact the culprits. A much more recent study confirmed these findings, but was able to show significant behavioral improvement in only about one out of 4 children.Trying an elimination diet with the advice and support of a pediatric allergist may be worth consideration when other medical conditions have been ruled out and nothing else is working. Keep in mind, however, that such hypoallergenic diets are usually nutritionally imbalanced and can cause vitamin and mineral deficiencies if not carefully prepared. Make sure that the diet includes alternate sources of important vitamins and minerals. If necessary, consult a nutritionist for a balanced menu plan. |
Off-the-wall testing. Just laugh at ads in newspapers promising to identify all your allergies by using magnets or by analyzing your hair. The diagnosis is hard enough with real tests.
Clinical ecology. This well-meaning group tends to see chemical hypersensitivity lurking behind every disorder. You owe yourself a more reasonable approach.
How to Cope with Food Allergy
How much effort you decide to expend on finding out what’s wrong and taking steps to correct it will depend on how uncomfortable your symptoms are. If you have reason to believe that eating a peanut or shrimp could kill you, your desire to eat peanuts will quickly subside. If a slice of bread baked with wheat flour gives you stomach problems, you’ll munch on rice cakes with relish.
As these two examples illustrate, the best way to treat adverse food reactions is prevention: avoiding the food. When that isn’t possible, or until the correct foods can be diagnosed, certain symptoms (especially respiratory ones) can at least be improved.
Drugs
Medications can only relieve symptoms, not remove the allergy. Still, prescription drugs can be extremely helpful. Great caution is used in prescribing these medications to pregnant and nursing women.
Decongestants, like those used to reduce cold symptoms, can reduce swelling and congestion.
Antihistamines. For sneezing, runny nose, itchy skin or hives, the doctor may prescribe an antihistamine such as fexofenadine (Allegra), hydroxyzine (Atarax), diphenhydramine (Benadryl), loratadine (Claritin), or cetirizine (Zyrtec). These drugs are not strong enough to counteract an anaphylactic reaction.
Nasal sprays. Cromolyn (Nasalcrom) and steroids such as Vancenase, Beconase, Flonase, Nasacort, and Nasonex discourage release of irritating histamines and the slow-reacting substance of anaphylaxis (SRS-A).
Bronchodilators in tablet or aerosol form aid breathing by opening air passages in the lungs. This is especially important for people with asthma who experience bronchospasms—spasmodic contractions of large air passages (bronchi) in the lungs. Examples are metaproterenol (Alupent), and albuterol (Proventil).
Watch Out For Hidden Problems Once you've realized you shouldn't eat something, you'll find it in unexpected places. Here are a few examples. Not all brands apply.
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Steroid creams such as hydrocortisone (Cortaid) can relieve itching.
Side effects are an occasional byproduct of these medications. They may include dry mouth, drowsiness, anxiety, frequent or painful urination, nausea, vomiting, loss of appetite, stomach pain, constipation or diarrhea, and headaches. New antihistamine preparations such as Claritin and Allegra are much less likely than older ones to dry out the mouth and nasal passages and cause overwhelming sleepiness.
Unconventional methods
You may hear of people who swear by unconventional treatments. But you should remember that they are called unconventional because either there is insufficient evidence to show that they work, or the evidence clearly shows that they are harmful.
In sublingual treatments, small amounts of the allergenic food are placed under the tongue. The idea is to “inoculate” the body against the food. This could be extremely dangerous if you were to have a strong allergic reaction during the treatment; and there’s no proof that it works.
Provocation/neutralization (P/N), or symptom provocation testing, calls for giving the person troublesome foods, in diluted form, in increasing increments until a reaction is provoked. Applications designed to neutralize the allergy follow. This method is questioned by many, although not all, mainstream physicians. Injections of the offending substance, useful for respiratory allergies, are not recommended for food as they could incite a severe reaction. Unsafe autogenous urine immunization, injections of your own urine, can lead to nephritis, a serious kidney disease.
Modifying Your Diet
To maintain good nutrition, if you must omit important foods indefinitely, consult a professional for personal diet planning and advice. A registered dietitian (R.D.) is certified and listed by the highly respected American Dietetic Association. Ask your doctor or hospital to recommend someone, or find out if your allergist or pediatrician works regularly with one. In some states, an equivalent title is Licensed Clinical Nutritionist. “Nutritionists” in general don’t necessarily have the same education or training.
Learn the many names for whatever ingredients you must avoid. Wheat may be listed as gluten, egg white as albumin. Your allergist or dietitian can provide a list of alternates.
Study the labels on food as well as on every commercial product that enters your mouth (see box, “Watch Out for Hidden Problems”). The new federal guidelines on food labeling helps make the list of contents easier to find and understand. Don’t assume you know what’s in a food just because you have read the label before; ingredients change. The more severe your symptoms, the more scrupulous you must be. And don’t hesitate to call the company directly. If a consumer information number isn’t listed on the label, call the company directly and ask to speak with a customer service representative.
Find out what foods can be substituted nutritionally for the ones you can’t eat. Many excellent books on allergy and nutrition provide such suggestions. Allergy associations can supply book lists.
Seek out the many cookbooks that provide tasty allergy-wise recipes. Enjoy the imposed adventure of exploring new foods and unfamiliar ethnic cuisines. Browse at health food stores, where you’ll find recipe books and helpful advice as well as food.
After educating yourself, educate others:
| • | Before dining at a friend's home, call and discuss your situation. If enough of the menu can't be adjusted to provide you with a full meal, offer to contribute a dish. Or eat something at home before you go. When you can help it, don't eat troublesome foods for social reasons or just because you're hungry. |
| • | Waiters are casually asked the ingredients of dishes on the menu every day. Make it clear why your questions are important. If your food server seems bored or unsure about the contents of a dish, ask to speak with the chef or order something else. Or, call the restaurant in advance to discuss your needs with the chef. In general, simple dishes, simply cooked, are safest. |
| • | Obtain a card from the Food Allergy Network (800-929-4040) listing your allergy or hypersensitivity. Show it to food servers for official-looking proof that your food "preferences" are a matter of health—and possibly life or death. |