Food allergies


A SELF-HELP WORKBOOK A step-by-step approach to uncovering food allergies and intolerances

Do you have a food allergy? If you think you do, you're among the more than one-fourth of adult Americans convinced that some of the foods they bite into wind up biting them back. Many make drastic changes in their diets, perhaps putting themselves at risk for nutritional deficiencies (Journal of the American Dietetic Association, January 1993). But despite the widespread worry, "True food allergies are quite rare, probably affecting less than 1 percent of the adult population," says Hugh Sampson, M.D., professor of pediatrics, allergy and immunology at Johns Hopkins University Medical Center.

Does this mean you don't have a food allergy? Not necessarily. "But it's more likely that a person who thinks he or she has a food allergy actually has a food intolerance," says allergist-immunologist Wesley A. Burks, M.D., associate professor of pediatrics at the University of Arkansas for Medical Sciences. Food intolerances--lactose intolerance is the most well known example--can be quite nasty in their own right. "Food intolerances produce some of the same uncomfortable symptoms that food allergies create, including bloating, cramping, gas and diarrhea," says Dr. Burks.

In any case, knowing once and for all whether you have an allergy, an intolerance or something else is the first step toward ending any suffering. This is especially important for those who actually do have a food allergy but suffer in silence, thinking their symptoms are just a normal part of life.

An allergy is the body's abnormal reaction to a harmless substance. In fact, even the healthiest foods may trigger a reaction in susceptible persons. Ironically, it's your body's immune system--designed to protect you from naughty invaders--that accounts for the symptoms. Histamine and other chemicals released from specialized cells called mast cells cause a wide range of allergic symptoms. Food-allergy symptoms can appear for the first time in adulthood. "Why allergies strike when they do remains a mystery," says Dr. Burks.

An intolerance can be due to a direct effect of some food or a deficiency of some enzyme, as in the case of lactose intolerance, where the enzyme lactase is deficient. And like allergies, intolerances can also strike for the first time in adulthood.

Knowing the difference between allergies and intolerances can be critical: Intolerances are often controlled by limiting the amount of the food eaten; with allergies, total avoidance is the rule. "Allergies are potentially fatal when they cause an anaphylactic reaction," says Dean Metcalfe, M.D., head of the allergic diseases section of the laboratory of clinical investigation at the National Institute of Allergy and Infectious Diseases (a division of NIH). Anaphylactic reactions are characterized by severe itching, hives, sweating, swelling of the throat, difficulty breathing and a sudden, severe drop in blood pressure, sometimes leading to loss of consciousness. If not treated immediately with epinephrine (adrenaline), anaphylactic shock can result in death. Asthmatics appear to be at special risk. Anyone who has ever experienced an allergic reaction to a food should carry a kit with him to self-administer epinephrine. These kits must be prescribed by a physician.

Figuring out whether you actually have a food allergy or intolerance or tracking down the culprit food is not easy. Just consider the sheer number of foods and ingredients you ingest at every meal. Even a simple breakfast menu can leave you asking, "Was it the cereal? The milk? Or the banana slices on top?"

If all this sounds daunting, rest assured, there is a way to get answers and to find relief. The first step is to do some detective work, and that's where the following workbook comes in. Maybe you've always believed that you had a food allergy but never knew for sure. Or you've suffered with symptoms that very well could be food related but you never seriously considered such a possibility. In either case, this self-help workbook can help. It guides you step-by-step through the key questions that leading allergists ask to discover whether you really do have a food allergy, a food intolerance or neither. It's intended for adults--not children--and is not meant as a substitute for seeing your doctor. Its main purpose is to help you gather the information that you and your doctor need to arrive at a conclusive diagnosis. However, if you have any type of severe reaction following a meal--such as difficulty breathing--you should contact your doctor immediately.

So simply answer the questions as you go along, and tally your scores at the end of each section. (Just some simple addition, nothing to be afraid of.) Depending on the numbers, you may be asked to skip ahead to another section. As you work your way through, you may discover some very useful clues. That's what we're after. Next comes a firm diagnosis--and only your doctor can provide that.

1. Do you have asthma?
1 0
If you have asthma, you are not only at greater risk for food allergies but also for anaphylactic reactions, which can be life threatening. (See also "Food Additives" on page 75.)

2. Did anyone eating with you get sick or experience unusual
feelings at the same time?
0 1
If others who ate the same meal also felt sick, it's very likely that you ate a contaminated food. Chief culprits: undercooked or improperly stored fish, meat, poultry, dairy and egg products.

3. Does your discomfort begin within 45 minutes of eating?
1 0
"Most allergic reactions occur within 45 minutes after ingesting the food," says Dr. Metcalfe. "And some reactions may be immediate." So if your reaction is delayed by hours, you're probably dealing with a food intolerance, not an allergy.

After the initial allergic response, which may occur within seconds or minutes, other symptoms may occur over several hours.

4. Do you have nonfood allergies?
1 0
"Most food allergies develop in allergic individuals," says Dr. Metcalfe. "If you're allergic to begin with--if you have been allergic to cats or ragweed, for example--you are at higher risk for developing a food allergy." Asthma and chronic skin conditions like eczema can be exacerbated by food allergies.

Total Points:

Assessment Add your total points for Part 1:

0-1 Food allergy unlikely; possibility of food intolerance. Skip to Part 4, "Food Intolerance," on page 72
2-3 Possibility of food allergy. Continue
4 Good chance of food allergy. Continue
This is a preliminary screening to narrow the possibilities. Next we look at specific symptoms.


5. Does your mouth itch after eating a suspect food?
5 0
Often the first symptom of an allergic reaction, because the lips, tongue, palate and throat are the first to come in contact with a food. When these areas react, this group of symptoms is sometimes called oral allergy syndrome.

Oral allergy syndrome is far more common in allergic people, and the syndrome has been linked to specific foods, including watermelon, cantaloupe, honeydew and bananas. So if you experience oral allergy syndrome in reaction to these or any other foods, it's likely you're allergic.

6. Does your nose run and do your eyes water after eating a
nonspicy food?
1 0
These symptoms of allergic rhinitis can occur with food allergies. However, the symptoms can also result from eating spicy foods, in which case it is called gustatory rhinitis, which has nothing to do with an allergic reaction.

7. Do you break out in a rash after eating certain foods?
1 0
Hives or skin rashes are among the most common allergic reactions to foods. However, skin reactions have a wide variety of causes beyond food allergies. And while food allergies frequently cause acute hives, they are rarely responsible for chronic hives.

8. Do you suffer frequent crying spells?
0 0
While nutrition may be related to emotional health, emotional reactions have not been scientifically linked to food allergies.

9. Do you suffer from irritable-bowel syndrome?
0 0
Though careful attention to diet may be crucial to overcoming this condition, IBS has not been scientifically linked to food allergy.

10. Do you have difficulty breathing after eating certain foods?
2 0
A food allergen can affect breathing both through swelling of the windpipe and through its effects on the lungs. Asthmatics are at special risk. However, there can be multiple triggers for an asthmatic attack besides foods.

11. Do you suffer from migraine headaches?
0 0
Migraines are not likely to be caused by food allergies. However, a substance called tyramine , found in red wine and aged cheeses, may trigger migraines in susceptible people. But this is a direct chemical reaction, not an immune-system allergy.

12. Do you suffer from chronic fatigue?
0 0
Though an individual's diet plays a role in overall energy levels, chronic fatigue has not been scientifically linked to food allergy.

13. Do you have abdominal pain after eating certain foods?
1 0
Bloating, cramping, gas and diarrhea are symptoms shared by allergies and food intolerance.

Total Points:

Assessment While several of the above symptoms could be a sign of food allergy, no single symptom tells us very much. "What we're looking for," says Dr. Burks, "are symptom clusters ."

For example, abdominal pain can be a symptom of allergy or intolerance. But when that pain is accompanied by a runny nose or skin rash, allergy becomes a far greater probability.

Add your total points for Part 2:

0-1 Food allergy unlikely. Skip to Part 4, "Food Intolerance," on page 72
2-4 Possibility of food allergy. Continue
5-10 Strong chance of food allergy. Continue

Walnuts Walnuts and other tree nuts--Brazil nuts, almonds, cashews, pistachios, filberts (hazelnuts), pecans, hickory nuts, pine nuts--are also among the most allergenic foods. If you are allergic to one tree-nut variety, there is a chance you're allergic to others--but not necessarily to peanuts (which are legumes).

Peanuts Though peanuts can be a healthy addition to most diets, they are among the most allergenic of all foods. In severely allergic persons, just a fraction of a peanut kernel can be enough to set off a reaction.

Shrimp and shellfish Although shrimp gets much attention, a broad class of shellfish can cause an allergic reaction. This class includes other crustacea (lobster, crab and prawn) and mollusks (snails, mussels, oysters, scallops, clams, squid and octopus).

Finfish Compared with other major food allergens, the proteins in fish are more vulnerable to heat and other forms of preparation. So some persons allergic to fresh cooked salmon or tuna can eat canned salmon or tuna without difficulty. But don't count on it.

In extremely severe fish allergies, even inhaling the vapors from boiling fish can set off a reaction.

Reactions to toxins in fish are sometimes mistaken for fish allergies. Scromboid poisoning from fish occurs when fish are contaminated with high levels of histamine, the primary irritant in classic allergic reactions.

Milk and milk products Most adverse reactions to milk are not allergies but rather lactose intolerance. Knowing the difference is critical: Those with lactose intolerance can generally manage small amounts of milk; with true milk allergy, any consumption of milk or milk-related proteins can be dangerous.

Tofu and soy foods Tofu is made from soy, a major allergen in children. Some adults react, too.

Wheat-containing foods Wheat allergy should not be confused with celiac disease (often called celiac sprue ), a rare condition resulting from an intolerance to gluten, which is present not only in wheat, but in rye, barley and oats, as well.

Assessment The foods in Part 3 top the list of suspects. The first four mentioned "account for 90 percent of all food allergies," says Dr. Sampson. So if you think you've consistently reacted to one of these foods (multiple allergies are rare), the odds are good that you have a true food allergy.

Skip to Part 5, "Diet Diary," on page 74


Carbohydrates Even if you don't have a food allergy, foods could be causing you trouble--even the healthiest of foods. In fact, a surprising culprit has been identified in the past few years: carbohydrates. Though generally a healthy part of the diet, new findings confirm the adage, "You can get too much of a good thing."

One type of carbohydrate, fiber, has long been known to cause gastrointestinal distress, often in those who have just begun eating a high-fiber diet. That's not surprising, because fiber is not digested on its trip through the small intestine. What is surprising are the recent indications that nonfiber carbohydrates--some sugars and starches--are not completely absorbed before reaching the colon. This is due to either a simple overload or a deficiency of key enzymes.

The symptoms can be just as unpleasant as food-allergy reactions, ranging from uncomfortable abdominal distention, gas and cramps to debilitating chronic diarrhea. Ironically, because many of the foods involved are so healthful, no one would ever suspect them as the source of trouble. If you do seem to react to them, you can first try incorporating them gradually into your diet, over a course of weeks. But if you still have problems, limit your intake.

Milk Milk and milk products contain a sugar, lactose , that is difficult for many people to digest. Lactose intolerance is caused by a lack of lactase , the enzyme that breaks down lactose. When unabsorbed lactose enters the colon, it starts causing trouble: "abdominal bloating, excessive gas production and pain from abdominal distention," says Dr. Metcalfe. These symptoms may be delayed two to eight hours.

Lactose intolerance is prevalent among African Americans, Native Americans and people of Hispanic, Asian or Mediterranean descent. Many people who've consumed little milk since childhood and begin drinking it again once they hit 40, to help fight off osteoporosis, encounter an unpleasant surprise: Lactase deficiency can develop during adulthood.

Fruit juices Fruit juices are high in fructose , a type of sugar touted in recent years as a healthy alternative to sucrose (common table sugar). Unfortunately, fructose is not as easily absorbed as other sugars, and this can lead to abdominal distress.

Apple juice also contains another potential troublemaker, sorbitol , a polyalcohol sugar. The fructose-sorbitol combination is a double whammy: Both together may lead to greater gastrointestinal trouble than either alone.

Glucose stimulates fructose absorption, so in place of apple juice, which has much more fructose than glucose, try grape juice, which has equal amounts of each.

Sugar-free candies Sorbitol is the primary sweetener used in many sugar-free candies and gum. Even small amounts may lead to malabsorption and gastrointestinal distress.

Sweetened soft drinks Most nondiet drinks contain high-fructose corn syrup (HFCS), which may add up to as much as 15 grams of fructose in an 8-ounce glass. Among the soft drinks loaded with HFCS are so-called natural drinks.

Fresh fruits Fruit is a major source of free fructose in the diet. And sorbitol is found in apples, pears, peaches and prunes. Best advice: If you think you're susceptible to this type of food intolerance, don't eat too much at once.

Beans As mentioned, high-fiber foods are known to cause bloating and gas in some people. And beans are naturally high in fiber. But in addition, some people may actually suffer from a bean intolerance. New research shows that maldigestion of the starch component of beans may also contribute to distress. Best advice: Add fiber to the diet slowly or limit it if this go-slow approach doesn't help.


A diet diary is a record of everything you eat, the time you eat it, the amount, and any symptoms that occur throughout the day.By examining the diet diary, you and your doctor may be able to spot unforeseen relationships between symptoms and the foods you have eaten. If you've answered the relevant questions in this workbook and you think you may indeed have a food allergy, consider keeping a food diary for one to two weeks. Then take it with you when you see your doctor.

Here are some tips to help you get the most useful information from your food diary:

Carry it with you at all times; don't wait until the end of the day to fill it in.
Write down everything that enters your mouth, including beverages, medicines and even chewing gum.
Indicate when any symptoms began and how long they lasted.
Be very specific. For example, don't write "ham sandwich," but instead list all the ingredients: "smoked ham, white bread, brown mustard..."
Whenever possible, attach ingredient labels to your food diary as a handy quick reference for your doctor. (Labels are extremely helpful when considering food additives.)
Even with a careful record of everything you eat, the data can sometimes fool you. So once you have identified a food as a potential suspect, you and your doctor will need to consider the following questions:

Did you react to the suspect food every time?

This is considered powerful evidence of a food-related problem, allergy or intolerance. However, it's not conclusive, so your doctor will need to confirm your suspicions with a skin-prick test.

If you don't react to the food every time, that doesn't always mean the food is innocent. In fact, there are several reasons your reaction to a food allergen may appear erratic.

How much of the suspected food did you eat?

"The most likely reason you wouldn't react every time is in the amount you're eating," says Dr. Metcalfe. "If you eat a little, you may not react; if you eat a lot, you may react.

"Say you ate lobster once and reacted, and then found the salad you just ate had lobster in it, but you didn't react. That doesn't mean you're not allergic. The key may be in the amount consumed."

Do you drink alcohol?

The ingestion of alcohol increases the absorption of food allergens. So if you take a drink, you're more susceptible to an allergic reaction. That means you may react to some food only after you've consumed it with alcohol.

Did you exercise after you ate?

In susceptible people, exercise can cause an allergic reaction to a food eaten before the exercise session. For some, the allergic reaction occurs in response to particular foods. Though rare, exercise-induced food allergy can be quite serious. Some people will have an anaphylactic reaction only after exercising. But prevention is simple; before exercising, just don't eat any food that you suspect of causing a problem.


Discovering that you have a true food allergy is a double-edged sword. On the one hand, it means always needing to be aware of what you're eating. On the other hand, knowing for sure lets you take steps to put an end to troubling symptoms--and maybe even save your life.

In about one-third of adult food allergies, reactions to the allergen disappear within one to two years following complete avoidance. However, the development of tolerance depends on the food, with the major allergens--peanuts in particular--least likely to relinquish their hold.

"In adults it's simply not reliable to stop eating a food and hope your allergy would not come back," says Dr. Metcalfe. "I think once you're allergic to a food, it's safest to assume you're allergic to that food for the rest of your life."

"Life for someone with a food allergy can seem overwhelming at times," says Anne Munoz-Furlong, founder and president of the Food Allergy Network, in Fairfax, Virginia, "especially since so much of the socializing we do is centered around food." Fortunately, the Food Allergy Network isan invaluable resource for helping people copeand continue to enjoy living. (See "Food Allergy Network" on page 66.)

The toughest part of living with a food allergy is knowing what to look out for. How tricky can it get? Well, the "plain" version of the "plain 'n' peanut candies" contains--you guessed it--peanuts. And "nondairy" products routinely contain casein , a protein derived from milk.

Even once you know what to look out for, finding it can be difficult. That's because the same food can be disguised under different names. For example, lactalbumin is a milk protein.

If it's tough deciphering label ingredients listed, it's impossible to detect ingredients that aren't. FDA regulations require listing of only those ingredients that make up 2 percent or more of a food product. Unfortunately, this seemingly small amount may be more than enough to set off an allergic reaction for some sensitive people.

Even when you think you know the ingredients in a product, labels change. "So you must always check, even when you think you know," says Munoz-Furlong. Also, be advised that food products imported from other countries may not be subject to the same disclosure standards.

If food labels are daunting, cafeterias and restaurants can be precarious. Since there are no labelsto read, you've got to count on the reliability of thechef to let you know the full ingredients in any menu selection. Munoz-Furlong has this advice: "Speak with the restaurant manager rather than relying on your waiter or waitress. And don't ever be afraid to ask questions!" Among the best: What other foods have been prepared on the same grill? If an allergic food has been cooked earlier, small amounts of cross-contamination could infiltrate your meal.


Once you've completed your diet diary, your doctor can begin testing.

Elimination diet A diet diary doesn't always point to specific food suspects. If allergy remains a possibility, a diet devoid of highly suspect allergens is eaten for a few weeks. (If the symptoms don't get better, the probability is that symptoms are not related to food allergy.) Then foods are added individually: If symptoms recur, allergy is suspected. The next step depends on the severity of your symptoms.

Skin-prick test (SPT) When nonsevere food allergies are suspected, a dilute extract of the suspected food is pricked into the skin. Swelling or redness does not always mean that you will experience allergic reactions to the food. But a negative reaction almost always indicates absence of allergy.

RAST test A radioallergosorbent test--or RAST--is an alternative to the skin-prick test. After drawing a small sample of blood, the allergist can measure the amount of allergen-specific IgE antibody in the blood that binds to a specific induced allergen. RAST is the test of choice when a severe allergy is suspected since you are not exposed to any potential allergen.

Exclusion diet Because the skin-prick test and RAST can produce "false positives," a positive finding must be confirmed. The next step is to exclude the food from the diet for two weeks. If exclusion brings an end to symptoms, we are close to concluding that a food allergy exists.

Double-blind, placebo-controlled food challenge This is the gold standard in food-allergy testing. The patient is given a series of capsules containing either a food extract or an inert substance. Neither the patient nor the doctor knows which is which. A positive reaction confirms existence of a food allergy.


To find a qualified allergist in your area, you can call the American College of Allergy and Immunology at (800) 842-7777, or call the American Academy of Allergy and Immunology at (800) 822-ASMA.



By Steve Schwade with Therese Walsh

The Food Allergy Network (FAN) helps people with food allergies and their families lead normal, happy lives while coping with the complexities food allergies bring. FAN helps people find their way through the maze of ingredients found in supermarket aisles and overcome the difficulties inherent in eating out at restaurants. It keeps members up to date on changes in label laws and new food products and ingredients. And it publishes handy, wallet-sized ingredient cards for each type of allergy.

To get a copy of FAN's new booklet, Understanding Food Labels, send $5 to Food Allergy Network, 4744 Holly Ave., Fairfax, VA 22030.

For free information and a sample newsletter, send a self-addressed, stamped business envelope.

Sometimes a person allergic to one food is allergic to other related foods--or even to nonfoods.

How does cross-reactivity between two substances happen? "The most likely explanation is that they have allergens in common or that closely resemble each other," says Dr. Metcalfe. In this way, a nonfood allergy can influence your reaction to a food, as is the case with ragweed allergy and cantaloupe: "People who have a cantaloupe allergy sometimes report they only have trouble with it during ragweed season," says Dr. Metcalfe.

If you're allergic to the plant in bold type, you may also react to the substance listed after it:

Ragweed Watermelon, cantaloupe, honeydew, bananas, chamomile tea, sunflower seeds

Mugwort Celery

Birch pollen Carrots, apples, hazelnuts and potatoes

Bananas Latex

If you're allergic to one food in the following families, you may be allergic to another:

Shellfish Lobster, crab, prawn, shrimp

Legumes Peas, beans, soybeans, peanuts

Lactose intolerance is the most common of all food intolerances. The following foods all contain the offending sugar lactose.

High Lactose:
Milk, including whole, low-fat, skim, condensed, evaporated, dried milk and buttermilk

Frozen yogurt
Ice cream, sherbet, ice milk
Mozzarella cheese
Cottage cheese
Other soft cheeses
Some Lactose:
Cheeses, including American cheese, Swiss cheese, Cheddar cheese, Parmesan cheese, cream cheese


Reactions to food additives are even more rare than food allergies. However, for two groups--those with asthma and chronic skin conditions--certain food additives can bring a significant, if small, chance of reaction.

Sulfites Sulfites are compounds used in foods as preservatives. Four percent of asthmatics react to sulfites. These persons are at risk for anaphylactic reactions. The problem comes from the release of sulfur dioxide gas, which may trigger a fall in pulmonary (lung) function. Sulfites have been sprayed on salad bars to fight browning, though this practice has now been regulated. Sulfites appear under the names sodium sulfite, sodium-or potassium bisulfite, or metabisulfites.

Monosodium glutamate (MSG) Asthmatics appear more at risk for reactions to MSG.

Food coloring In people with chronic hives, reaction to certain food colors is probably on the order of 5 to 10 percent. The greatest offenders appear to be the so-called azo dyes, which include FD&C red #4 (ponceau), FD&C yellow #6 and FD&C yellow #5 (tartrazine). Tartrazine is also suspected of exacerbating asthma, though the jury is still out.

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