Food Allergies: When Food Becomes the Enemy

Imagine what it would be like if eating a peanut butter sandwich or some shrimp, or drinking a tall glass of milk left you vomiting, gasping for breath, and furiously scratching a fresh crop of hives. For some people with food allergies, that's reality.

A food allergy, or hypersensitivity, is an abnormal response to a food triggered by the immune system. While many people often have gas, bloating or another unpleasant reaction to something they eat, this is not an allergic response. Such a reaction is thought to not involve the immune system and is called "food intolerance."

Only about 1.5 percent of adults and up to 6 percent of children younger than 3 years in the United States--about 4 million people--have a true food allergy, according to researchers who have examined the prevalence of food allergies.

It's critical for people who have food allergies to identify them and to avoid foods that cause allergic reactions. Some foods can cause severe illness and, in some cases, a life-threatening allergic reaction (anaphylaxis) that can constrict airways in the lungs, severely lower blood pressure, and cause suffocation by the swelling of the tongue or throat.

An estimated 150 Americans die each year from severe allergic reactions to food, says Hugh A. Sampson, M.D., director of the Elliot and Roslyn Jaffe Food Allergy Institute at Mount Sinai School of Medicine in New York City and a food allergy expert.

The Food and Drug Administration's Center for Food Safety and Applied Nutrition has made it a high priority to boost consumer and food industry awareness of food allergens. As part of these efforts, the FDA is conducting food allergen education programs for consumers and industry. The agency also is developing a strategy for clear, easy-to-understand labeling of food allergens.

Allergic Reactions

Food normally doesn't provoke a response from the human immune system, the body's defense against microbes and other threats to health. In food allergies, two parts of the immune response are involved, according to researchers at the National Institute of Allergy and Infectious Diseases. One is the production of an antibody called immunoglobulin E (IgE) that circulates in the blood. The other part is a type of cell called a mast cell. Mast cells occur in all body tissues but especially in areas that are typical sites of allergic reactions, including the nose, throat, lungs, skin, and gastrointestinal tract.

People usually inherit the ability to form IgE against food. Those more likely to develop food allergies come from families in which allergies such as hay fever, asthma, or eczema are common.

A predisposed person must first be exposed to a specific food before IgE is formed. As this food is digested for the first time, tiny protein fragments prompt certain cells to produce specific IgE against that food. The IgE then attaches to the surface of mast cells. The next time the particular food is eaten, the protein interacts with the specific IgE on the mast cells and triggers the release of chemicals such as histamine that produce the symptoms of an allergic reaction.

If the mast cells release chemicals in the nose and throat, the allergic person may experience an itching tongue or mouth and may have trouble breathing or swallowing. If mast cells in the gastrointestinal tract are involved, the person may have diarrhea or abdominal pain. Skin mast cells can produce hives or intense itching.

The food protein fragments responsible for an allergic reaction are not broken down by cooking or by stomach acids or enzymes that digest food. These proteins can cross the gastrointestinal lining, travel through the bloodstream and cause allergic reactions throughout the body.

The timing and location of an allergic reaction to food is affected by digestion. For example, an allergic person may first experience a severe itching of the tongue or "tingling lips." Vomiting, cramps or diarrhea may follow. Later, as allergens enter the bloodstream and travel throughout the body, they can cause a drop in blood pressure, hives or eczema, or asthma when they reach the lungs. The onset of these symptoms may vary from a few minutes to an hour or two after the food is eaten.

Most Likely Suspects

Food allergy patterns in adults differ somewhat from those in children. The most common foods to cause allergies in adults are shrimp, lobster, crab, and other shellfish; peanuts (one of the chief foods responsible for severe anaphylaxis); walnuts and other tree nuts; fish; and eggs.

In children, eggs, milk, peanuts, soy and wheat are the main culprits. Children typically outgrow their allergies to milk, egg, soy and wheat, while allergies to peanuts, tree nuts, fish and shrimp usually are not outgrown.

Adults usually do not lose their allergies.

A Growing Problem

"The prevalence of food allergy is growing and probably will continue to grow along with all allergic diseases," says Robert A. Wood, M.D., director of the pediatric allergy clinic at Johns Hopkins Medical Institutions in Baltimore.

Wood says that research over the last three decades indicates that the number of people with allergies is skyrocketing in developed and developing countries, but not in underdeveloped areas.

"The fewer germs in terms of infection and the environment, the more time the immune system has to worry about things like allergens," says Wood. "Recent studies indicate that growing up in a large family or daycare center actually decreases the likelihood of developing an allergy."

Wood, who has had a severe peanut allergy since he was a toddler, says allergic reactions to foods can vary dramatically. "They can range from just a mild rash to very severe swelling in the throat and the airways in the lungs so that there is a complete inability to breathe," he says.

Wood's parents learned of their son's allergy when they introduced him to peanut butter. "The first time I had peanut butter I developed a rash and severe swelling in my face," he says. "I'm extremely allergic. Just being around when a peanut shell is broken and dust is being released is enough to cause a reaction.

"I've had a number of very dangerous reactions," Wood says. "People with a food allergy typically walk around with a little bit of fear all the time. Once it starts, it's a fear-generating experience."

Multiple Allergies

When Sarah Buster of Columbia, Md., was 4 months old, her parents discovered that an allergy to milk was causing her eczema, a chronic skin inflammation. Her skin improved with a switch to a soy-based formula. Sarah's doctor believed there was little cause for concern since many infants have eczema and most outgrow it by age 2. Sarah didn't. Tests later indicated that she was allergic to eggs, peanuts, tree nuts, penicillin, tree pollen, ragweed, dust mites, and dogs and cats.

It was then that Sarah's parents, Mike and Brenda Buster, began reading food labels as carefully as they would a legal contract. They joined a food allergy advocacy group, replaced the carpet in Sarah's bedroom and throughout the house with hardwood floors, placed dust mite covers over her bedding, gave away the family's dogs, and kept Sarah indoors as much as possible.

A small wooden chair with a wicker seat has taken the place of upholstered furniture for Sarah, and devices that filter dust, pollen and other particles hum both upstairs and downstairs.

For a time, soaking baths and ointment head-to-toe helped keep her skin moist, and a prescription antihistamine eased the itching enough so she could sleep. However, Sarah's eczema soon worsened again.

"Sarah's itching would be so severe that we could stand right by her and call her name and she would not respond because she was so focused on scratching," says Brenda Buster. "She would scratch until she bled because the pain felt better than the itch."

Finally, allergists at Johns Hopkins eliminated all conventional food and put her on a special formula made of amino acids. Sarah also started a four-month regime of prednisone, a drug that mimics the effects of the body's natural corticosteroid hormones and suppresses the activity of the immune system.

Eventually, her diet was expanded to six foods that doctors believed she was not allergic to: turkey, pork, rice, apples, grapes and tomatoes, supplemented by the special formula.

Sarah's skin cleared and after several months she began a series of dietary "challenges"--tests to determine whether specific foods cause an allergic reaction. Several years later, Sarah eats a more varied diet, and the Busters maintain a list of safe foods and those that cause an allergic reaction.

"The most difficult thing I have faced with my allergies is that when I see my friends eating something that I know I can't have, it just makes me feel left out," says Sarah.

"We never order food for Sarah at a restaurant because, even if the ingredients in the food itself are safe, there is a considerable chance for cross-contamination with something that's unsafe for her to eat," says Mike Buster. "For example, a baked potato might be safe, but if the person preparing the potato even touched a dairy, nut or egg product and then touched the potato, Sarah could have a serious reaction.

"We go out to eat, but we bring all her food with us," he says. "It's just not worth taking the chance."

Wood, who cares for Sarah at Johns Hopkins, says, "She's got it a lot tougher than someone who just has a peanut allergy. She's dealing with this stuff on an every-single-meal basis. Her parents have really helped provide her with a wonderful life."

That life includes her favorite activities--ice-skating (she likes the cool air of the rink) and swimming (the moisture and chlorine are beneficial to her skin, according to her doctors).

Sarah continues to outgrow some of her allergies, and has added about a dozen foods into her diet over the past year, Wood says.

"The taste in my mouth when I'm trying something new is very different," says Sarah. "Strawberries felt hard because of the seeds. They tasted great but I didn't like the texture, so my dad tried to take the seeds out. I still didn't like the strawberries that much, but I kept reminding myself over and over again that if I passed the test, I would be able to have a lot of things with strawberries in it. Like now I can have strawberry Skittles."

The food at Sarah's Montessori school is nut-free, and on special school occasions, Brenda Buster tries to prepare something that Sarah and her classmates can enjoy, such as some types of candy, homemade cupcakes made without eggs or dairy products, a nondairy frozen dessert, or popcorn prepared at home.

"We make our own bread and most other foods," says Brenda. "Although we do have several more products we can buy, including one brand of potato chips and one brand of pretzels, saltines and several types of canned vegetables."

Still, the Busters must be vigilant and can be found constantly checking labels. For example, a type of food may be safe from one manufacturer but not from another. "One brand of candy corn may be OK, while another contains eggs," says Brenda.

Even foods that have proved to be safe previously can subsequently cause a problem. "Manufacturers can change the ingredients without changing the packaging," adds Mike Buster. "We appreciate manufacturers who clearly label their products."

Food Labeling: A Critical Component

Currently, the only way to treat food allergies is to avoid the foods that trigger reactions. Even the most diligent label-readers and ingredient-checkers likely will be inadvertently exposed to proteins that elicit an allergic response at some point. That's why Wood, Sarah and others with food allergies severe enough to cause anaphylactic reactions should wear medical alert bracelets or necklaces and carry a syringe of adrenaline (epinephrine) obtained by prescription from their physicians.

Anaphylactic allergic reactions can be fatal even when they begin with mild symptoms such as a tingling in the mouth and throat or gastrointestinal discomfort. Antihistamines and bronchodilators can be used to treat less severe symptoms.

FDA's Role

Since 2000, the FDA has presented information on allergen risk and labeling requirements at more than a dozen locations nationwide, says Kenneth J. Falci, Ph.D., who leads the FDA's initiatives on food allergies.

The meetings provide the FDA with firsthand accounts from people with food allergies and data that can be used to improve consumer labeling.

The FDA's food allergy efforts include focusing on the eight most common food allergens: milk, eggs, fish, wheat, tree nuts, peanuts, soybeans and crustaceans (such as shrimp and crabs). Proteins in these eight major foods are estimated to cause 90 percent of the allergic reactions in the United States.

Industry Response

Food manufacturers and consumer groups are working with the FDA to increase public awareness of the seriousness of food allergen reactions and to ensure that allergens are appropriately labeled in food products.

An allergen labeling program and a "code of practice" developed by the National Food Processors Association that calls for listing the eight most common food allergens in "plain language" are among the voluntary efforts being undertaken.

An example of "plain language" is using the word "milk" in a product's ingredient list as well as the less familiar "caseinate" or using "eggs" in addition to "albumin."

Falci says FDA investigators nationwide are being trained how to properly inspect food-processing plants for allergen control procedures. In addition, FDA officials have updated a 1996 notice to the food industry addressing the problem of undeclared allergens in food by recently publishing a compliance policy guide.

Falci regularly speaks to food industry gatherings across the country to discuss many allergen topics, including methods being used by some processors to avoid problems related to food allergies.

"Sharing 'best practices' in the industry through workshops is a really good way to get people to talk to each other," Falci says. "This is not a competitive edge issue. This is a safety concept, and sharing these thoughts is helpful to everyone in the industry.

"Altering production scheduling is a practice that can have a huge impact on minimizing the inadvertent introduction of undeclared allergens," says Falci. "Manufacturers who use shared equipment to process foods without allergens can benefit from following a carefully laid out production plan, such as running non-allergen-containing products first, followed by those containing allergens, then a clean-up step."

The payoff? The shared equipment is less likely to contaminate other products with undeclared allergens.

The FDA is meeting with the food industry, consumers, trade associations and consumer advocate groups to discuss ways to improve the identification of food allergens within the ingredients list.

Falci says that labeling food allergens in plain language--a source statement simple enough for a child to know if an ingredient is derived from soy or milk, for example--and precautionary food labeling are among the subjects discussed.

Labeling Policy

The Federal Food, Drug, and Cosmetic Act requires, in virtually all cases, that all the ingredients of a food be listed on the food label. Two exemptions to the labeling requirements recently have been involved in a number of reported food allergen reactions: the collective naming of spices, flavorings, and colorings; and insignificant levels of additives in a food that do not have a technical or functional effect on the final product. The FDA, however, does not consider food allergens eligible for the latter labeling exemption. The agency also strongly encourages the declaration of an allergenic ingredient in a spice, flavor, or color.

"While the FDA believes that food processors make a sincere effort to label the ingredients in their food products completely, it's clear from data on food recalls that firms do miss including some allergenic ingredients on their food labels," says Falci.

Gaps in Allergen Labeling

Between September 1999 and March 2000, FDA researchers working with state inspectors from Wisconsin and Minnesota inspected 85 bakery product, ice cream and candy manufacturers for allergen labeling and cross-contamination issues, with a focus on peanut and egg allergens. Many of the firms in the study were small- to medium-sized operations. The joint study was prompted, in part, by a jump in the number of national recalls due to allergy-related ingredients not being listed on labels.

Samples were collected for egg and peanut protein analysis only when labeling or cross-contamination issues were identified by the investigator. Eighteen of the 73 samples (25 percent) of ice cream, bakery and candy food products tested positive for peanut allergens, although peanuts were not listed on product labels. Investigators also found that companies unintentionally introduced food allergens into other foods through poor cleaning and cooking schedules or improper cleaning of utensils.

"These findings show that more work is needed," Falci says.

The inspectors also found that just over half of the manufacturers checked their products to ensure that the labels accurately reflected all of the ingredients.

"We certainly have legal authority at the moment to allow for recalls of undeclared allergens, and recalls are occurring for that reason," Falci says. "We're only in the beginning stages of negotiating and talking with the food industry about some things we'd like to potentially see on the label. However, the industry is beginning to take voluntary actions, which we applaud."

Consumer Involvement

The Food Allergy & Anaphylaxis Network (FAAN), based in Fairfax, Va., has been an advocate for simple, clear and accurate food labels for a decade. "Reading food labels is the only way that food-allergic consumers can avoid dangerous allergens in packaged food," says Anne Muñoz-Furlong, FAAN founder and president. "If food manufacturers don't follow good manufacturing practices and carefully control that what is in the package matches what is on the label, we are all in big trouble."

According to Muñoz-Furlong, many large food companies have long been aware of how serious food allergies can be, and have made appropriate changes in their manufacturing and labeling practices. There are still many more companies that have yet to take the issue seriously.

For example, Muñoz-Furlong says that today there are more than a dozen ways to indicate the presence of milk protein without using the word "milk." Another common problem is the term "nondairy." Many consumers mistakenly believe that nondairy means there is no milk in a product. Current labeling guidelines allow the use of "nondairy" when the foods contain milk byproducts.

In addition, manufacturers may use the term "natural flavors" even when the product contains major allergens. To avoid a major allergen, a food-allergic consumer would need to call the manufacturer before purchasing the product to confirm that an allergen was present.

Common Symptoms of an Allergic Reaction to Food

• Symptoms typically appear within minutes to two hours after a person has eaten the food to which he or she is allergic.
• Tingling sensation in the mouth
• Swelling of the tongue and throat
• Difficulty breathing
• Hives
• Vomiting
• Abdominal cramps
• Diarrhea
• Drop in blood pressure
• Loss of consciousness, and death.