When eating is risky

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Do you start itching whenever you eat peanuts? Does seafood cause your stomach to chum? Symptoms like these cause millions of Americans to suspect they have a food allergy.

But true food allergies affect a relatively small percentage of people: Experts estimate that only 2 percent of adults, and from 2 to 8 percent of children, are truly allergic to certain foods. Food allergy is different from food intolerance, and the term is sometimes used in a vague, all-encompassing way, muddying the waters for people who want to understand what a real food allergy is.

"Many people who have a complaint, an illness, or some discomfort attribute it to something they have eaten. Because in this country we eat almost all the time, people tend to draw false associations [between food and illness]," says Dean Metcalfe, M.D., head of the Mast Cell and Physiology Section at the National Institute of Allergy and Infectious Diseases.

For example, food intolerance may produce symptoms similar to food allergies, such as abdominal cramping. But while people with true food allergies must avoid offending foods altogether, people with food intolerance can often eat small amounts of the offending food without experiencing symptoms.

Lactose intolerance, for instance, is sometimes mistaken for milk allergy. Lactose intolerance is a problem of digestion due to an enzyme deficiency, with cramps and diarrhea the common hallmarks. Estimates are that about 80 percent of African-Americans have lactose intolerance, as do many people of Mediterranean or Hispanic origin, It is quite different from the true allergic reaction some have to the proteins in milk. Unlike allergies, intolerances generally intensify with age.

Dangerous Dishes
For people with true food allergies, the simple pleasure of eating can turn into an uncomfortable-and sometimes even dangerous-situation. For some, food allergies cause only hives or an upset stomach; for others, one bite of the wrong food can lead to serious illness or even death.

FDA regulates drugs used to treat severe allergic reactions and has recently issued regulations under the Nutrition Labeling and Education Act of 1990 to make such reactions less likely.

The early Greek philosopher and physician Hippocrates was one of the first to note that cow's milk caused health problems for some people, but it was not until the early 1900s in Europe that the first scientifically documented food allergy reports began to appear. The word "allergy" is derived from a Greek word meaning "altered reaction," and initially conveyed the idea that certain substances could cause adverse reactions in some people while having no effect on the public at large.

By the mid- 1920s, allergists had defined food allergy as an abnormal response of the immune system to an otherwise harmless food. Food allergens, those parts of food causing allergic reactions, are usually proteins. When the allergen passes from the mouth into the stomach, the body recognizes it as a foreign substance, producing antibodies to halt the invasion. In allergic individuals, as the body fights off the invasion, symptoms begin to appear throughout the body. The most common sites are the mouth (swelling of the lips or tongue, itching lips), digestive tract (stomach cramps, vomiting, diarrhea), the skin (hives, rashes or eczema), and the airways (wheezing or breathing problems).

Food allergies are much more common in infants and young children, who often later outgrow them. Increased susceptibility of young infants to food allergic reactions is believed to be the result of immunologic immaturity and, to some extent, intestinal immaturity. Older children and adults may lose their sensitivity to certain foods if the responsible food allergen can be identified and completely eliminated from the diet, although some food allergies can last a lifetime.

Heredity may cause a predisposition to have allergies of any type. Some experts believe that, rarely, a specific allergy can be passed on from parent to child. Several studies have indicated that exclusive breast-feeding, especially with maternal avoidance of major food allergens, may deter some food allergies in infants and young children. (Smoking during pregnancy can also result in the increased possibility that the baby will have allergies.) Most patients who have true food allergies have other types of allergies, such as dust or pollen, and children with both food allergies and asthma are at increased risk for more severe reactions.

Repeated exposure to allergens starts sensitizing those who are susceptible. Cow's milk, eggs, wheat, and soy are the most common food allergies in children. An early peanut allergy may be lifelong. Adults are usually most affected by nuts, fish, shellfish, and peanuts.

Life-Threatening Reactions
The greatest danger in food allergy comes from anaphylaxis, a violent allergic reaction involving a number of parts of the body simultaneously. Like less serious allergic reactions, anaphylaxis usually occurs after a person is exposed to an allergen to which he or she was sensitized by previous exposure (that is, it does not usually occur the first time a person eats a particular food). Although any food can trigger anaphylaxis (also known as anaphylactic shock), peanuts, tree nuts, shellfish, milk, eggs, and fish are the most common culprits. As little as one-fifth to one-five-thousandth of a teaspoon of the offending food has caused death.

Anaphylaxis can produce severe symptoms in as little as 5 to 15 minutes, although life-threatening reactions may progress over hours. Signs of such a reaction include: difficulty breathing, feeling of impending doom, swelling of the mouth and throat, drop in blood pressure, and loss of consciousness. The sooner anaphylaxis is treated, the greater the person's chance of surviving. The person should be taken to a hospital emergency room, even if symptoms seem to subside on their own.

There is no specific test to predict the likelihood of anaphylaxis, although allergy testing may help determine what a person may be allergic to and provide some guidance as to the severity of the allergy. Experts advise people who are susceptible to anaphylaxis to carry medication, such as injectable epinephrine, with them at all times, and to check the medicine's expiration date regularly. Doctors can instruct patients with allergies on how to selfadminister epinephrine. Such prompt treatment can be crucial to survival.

Injectable epinephrine is a synthetic version of a naturally occurring hormone also known as adrenaline. For treatment of an anaphylactic reaction, it is injected directly into a thigh muscle or vein. It works directly on the cardiovascular and respiratory systems, causing rapid constriction of blood vessels, reversing throat swelling, relaxing lung muscles to improve breathing, and stimulating the heartbeat.

Epinephrine designed for emergency home use comes in two forms: a traditional needle and syringe kit known as Ana-Kit, or an automatic injector system known as Epi-Pen. Epi-Pen's automatic injector design, originally developed for use by military personnel to deliver antidotes for nerve gas, is described by some as "a fat pen." The patient removes the safety cap and pushes the automatic injector tip against the outer thigh until the unit activates. The patient holds the "pen" in place for several seconds, then throws it away.

While Epi-Pen delivers one premeasured dosage, the Ana-Kit provides two doses. Which system a patient uses is a decision to be made by the doctor and patient, taking into account the doctor's assessment of the patient's individual needs.

Advice from Study
Hugh A. Sampson, M.D., and colleagues at Johns Hopkins University School of Medicine in Baltimore, Md., published a study of anaphylactic reactions in children in the Aug. 6, 1992, issue of The New England Journal of Medicine. The study involved 13 children who had severe allergic reactions to food: Six died, and seven nearly died. Among the study's conclusions:

Asthma, a disease with allergic underpinnings, was common to all children in the study.
Epinephrine should be prescribed and kept available for those with severe food allergies.
Children who have an allergic reaction should be observed for three to four hours after a reaction in a medical center capable of dealing with anaphylaxis.
Anne Munoz-Furlong, who founded The Food Allergy Network for people with food allergies in 1991 after struggling to deal with her own child's allergies, comments: "My youngest daughter was diagnosed with milk and egg allergies when she was 9 months old, nine years ago. We tried to lead a life around her restricted diet. For example, we had Jell-O mold for her first birthday because I didn't know it was possible to create a cake without milk or eggs. I knew there must be other families struggling with the same issues."

Finding the Forbidden
Because there is no "cure" for food allergies other than strict avoidance of an offending food, one of the biggest problems those with food allergies face is verifying whether a forbidden product is contained in a particular food. For example, in Sampson's study, all six deaths occurred because either the child or the parent was unaware the food contained a substance to which the child was allergic. Munoz-Furlong says the Nutrition Labeling and Education Act, which requires more complete food labeling, should greatly help people with food allergies to avoid dangerous foods.

"The new labeling changes will make it easier for the consumer to readily identify things they could be allergic to," says Linda Tollefson, D.V.M., chief of the epidemiology branch at FDA's Center for Food Safety and Applied Nutrition. "Before this law was passed, true allergens were required to be on the label, but the exceptions were standardized foods, which will now have to list all ingredients."

According to Elizabeth J. Campbell, director of the center's division of programs and enforcement policy, the principle underlying standardized foods originally was that people basically knew what was in various foods.

"Originally food standards were adopted to ensure uniformity. If you saw a product labeled mayonnaise, food standardization meant it had to be mayonnaise. People used to know what was in mayonnaise; nowadays they have to be told that mayonnaise contains both eggs and oil," Campbell says. "Years ago when the law was first written to provide for standards of identity for certain foods, it only required that optional ingredients be declared. The new law stipulates that all ingredients in standardized foods must be declared." (See "Ingredient Labeling: What's in a Food?" in the April 1993 FDA Consumer.)

Campbell believes that once the labeling is in place, consumers will have the information they need to make correct food choices. "In most cases, ingredients have to be labeled simply because they are ingredients, not because they are unsafe," she stresses. "For those with food allergies, I think it is more of a patient education problem."

Food additives, such as sulfites and certain colors, can also cause problems for people sensitive to them. (See "A Fresh Look at Food Preservatives" in the October 1993 FDA Consumer and "From Shampoo to Cereal: Seeing to the Safety of Color Additives" on page 14 of this issue.)

"If you have a food allergy, you really have to alter your life," Tollefson says. "You have to really read labels, and really be careful about what you eat."

Steve Taylor, Ph.D., a professor and head of the Department of Food Science and Technology at the University of Nebraska in Lincoln, says the biggest problem for people with food allergies is restaurant food. Historically, restaurants have been regulated by local health departments and have not had to label foods.

"For many restaurants, labeling of food products they serve would cause horrendous problems ... what about chalkboard menus? How would you include all the ingredients? Enforcement would be a nightmare," he admits.

But steps are being taken to better educate restaurant employees. The Food Allergy Network and The American Academy of Allergy and Immunology, along with The National Restaurant Association, recently produced a pamphlet on food allergies, which has been distributed to 30,000 members of the association. The brochure explains what restaurants can do to help customers who need to avoid certain foods, defines anaphylaxis, and advises employees on what to do if food allergy incidents occur.

John A. Anderson, M.D., director of the Allergy and Immunology Training Program at Henry Ford Hospital in Detroit, says changes in food habits may be responsible for the feeling some physicians have that food allergies may be on the rise.

"You could make a case for the fact that we are introducing peanuts, in the form of peanut butter, to people at a very young age, which would affect the prevalence rate for people who are sensitive to that allergen," he notes. "In Japan, where they use more soy, there is a higher prevalence of soy allergy. My feeling is that as soy, a cheap protein supplement, is put in a lot of commercial foods you will see an increase in the rate of sensitivity worldwide."

Metcalfe says that if food allergies are rising, it is due to more common use of foods that tend to be allergenic. He cites milk as a source of protein supplement in many prepared foods, and points out that people are eating more exotic seafood and more fish.

"But it's important to remember that the majority of people with true food allergies are allergic to three or fewer foods," Metcalfe says.

Other than advising anyone with a known or suspected severe food allergy to carry and know how to self-administer epinephrine, there is no treatment for food allergy other than to eliminate the offending food. But Metcalfe is optimistic about the future.

"I don't think it is likely a drug will be found to prevent food allergies. But I do think within 10 years we will see allergy shots available for some of the more common food allergies, because we are learning to identify and purify food allergens. I think we will see some development of immunotherapy for food allergies," he says.

More Information
For more information about food allergies, contact the following groups:

The Food Allergy Network
4744 Holly Ave.
Fairfax, VA 22030-5647
(703) 691-3179

American Academy of Allergy and Immunology
611 East Wells St.
Milwaukee, WI 53202
(414) 272-6071

Physician Referral Hotline
(1-800) 822-ASMA

The American Dietetic Association
216 W. Jackson Blvd.
Chicago, IL 60606-6995
(1-800) 877-1600
For a free copy of An FDA Consumer Special Report: Focus on Food Labeling, which includes the article on ingredient labeling, write to FDA, HFE-88, 5600 Fishers Lane, Rockville, MD 20857.

DIAGRAM: Common Sites for Allergic Reactions

PHOTO: Family dining in restaurant.

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By Audrey T. Hingley

Audrey T. Hingley is a writer in Mechanicsville, Va.

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