I Think I'm Allergic To...
Do you, or someone you know, shun certain foods because you are "allergic?" Surveys show that nearly one-third of all adults believe they have a food allergy. The following seeks to shed light on such frequently asked questions as: What is a food allergy? How do you know if you have one? What should you do if you have a food allergy? And, if it is not a food allergy, what might it be?
Myth: Lots of people have food allergies.
Reality: "From talking with the public, you might think almost everyone has a food allergy," said Daryl Altman, M.D., Fellow of the American College of Allergy, Asthma and Immunology and researcher at the Allergy Information Services in Long Island, New York. "In surveys, nearly one-in-three American adults indicated he or she was allergic to some food." But in reality, the most conservative estimates indicate two percent of the population in the United States are food allergic. Children are more susceptible than adults to food allergy—up to five percent have some type of food allergy. However, common allergens such as eggs and milk are typically outgrown by age five.
The eight most common food allergens in people are: Peanuts, tree nuts (for example, almonds, pecans and walnuts), dairy, soy, wheat, eggs, fish and shellfish (for example, shrimp and crab). Nevertheless, allergies to nearly 175 different types of food have been documented. "These foods are responsible for over 90 percent of serious allergic reactions to food," stated Susan L. Hefle, Ph.D., co-director of the Food Allergy Research and Resource Program at the University of Nebraska-Lincoln.
Myth: A food allergy means I'll just get a runny nose, right?
Reality: No—although food allergy is rare, it is a serious condition and should be diagnosed by a board-certified allergist. Food allergy is a reaction of the body's immune system to a certain component, usually a protein, in a food or ingredient. The reactions can be uncomfortable and mild including vomiting, diarrhea, skin rashes or runny nose, sneezing, coughing and wheezing, and may occur within hours or days after eating. However, anaphylaxis, a more serious and life-threatening reaction, may occur. Anaphylaxis is a rapidly occurring reaction that often involves hives and swelling, enlarging of the larynx with a choking sensation, wheezing, severe vomiting, diarrhea and even shock. These symptoms can also occur within minutes, hours or days. "Food allergic patients should have an anaphy-laxis reaction plan worked out ahead of time with their allergist," according to Anne Muñoz-Furlong, president and founder of The Food Allergy Network. "The plan should be practiced with family and friends in case of an emergency."
What is an Allergic Reaction?
An allergic reaction occurs when a susceptible person is exposed to a specific protein. Because the body perceives this protein (an allergen) as being a threat, it produces a special material—a substance that recognizes allergens—known as Immunoglobulin E (IgE) antibody. A person who has a tendency to develop allergies tends to produce increased amounts of IgE. After the initial exposure to a specific allergen (such as "cat" or "dog" protein) the body reacts to future exposures by creating millions of IgE antibodies. These newly produced IgE antibodies then connect to special blood cells called basophils, and special tissue cells called mast cells. These cells are then "stimulated" to release histamine which causes the allergy symptoms: Itchy watery eyes and nose, scratchy throat, rashes, hives, eczema and even life-threatening anaphylaxis. |
Myth: Any negative reaction to a food is a food allergy.
Reality: Adverse reactions to food can have many causes. If something does not "agree with you," it does not necessarily mean you are allergic to it. Food allergy is a very specific reaction involving the immune system of the body, and it is important to distinguish food allergy from other food sensitivities. Whereas food allergies are rare, food intolerances, which are the other classification of food sensitivities, are more common. Intolerances are reactions to foods or ingredients that do not involve the body's immune system. Intolerance reactions are generally localized, transient and rarely life threatening with one possible exception-sulfite sensitivity. "A good example of a food intolerance is lactose intolerance. And, it is extremely important to know the difference between it and a milk allergy," said Robert K. Bush, M.D., University of Wisconsin. He emphasized that, "Whereas lactose intolerance may result in a bloated feeling or flatulence after consuming milk or dairy products, milk allergy can have life-threatening consequences. The milk allergic patient must avoid all milk proteins."
Myth: I think I'm allergic to a food—I just won't eat it, so I don't need to be seen by a doctor.
Reality: Just thinking you are allergic to a food does not mean you have an allergy. To properly diagnose a food allergy or sensitivity the offending substance must be accurately identified. Avoiding a food may deprive you of food choices and important nutrients, and could be dangerous if the allergen is actually different. Diagnosis of a food allergy can be complex, with three major components. The first and most important is involving a board-certified allergist, preferably a food allergy specialist. Second, a history of a specific food causing an allergic reaction is necessary; a food diary can help. Third, an IgE antibodies test, is only useful when combined with the former components, but it does not always pinpoint a food allergy (see sidebar). Hugh Sampson, M.D., director, Food Allergy Clinic, Mt. Sinai Medical Center, and chair of the American Academy of Allergy, Asthma and Immunology's Adverse Reactions to Foods Committee, emphasized an examination by a board-certified allergist: "Due to many people claiming to have food allergies, many physicians have become "desensitized" to taking their symptoms seriously."
The Double-Blind Placebo-Controlled Food Challenge
This test, considered the "gold standard" for food allergy testing, is performed by a board-certified allergist. The suspected allergen is placed in a capsule or hidden in food, and fed to the patient under strict supervision. Neither the allergist, nor the patient, is aware of which capsule, or food, contains the suspected allergen—hence the name "double-blind." In order for the test to be effective, the patient must also be fed capsules or food which do not contain the allergen to make sure the reaction, if any, being observed is to the allergen and not some other factor—hence the name "placebo-controlled." It is tests of this kind that have enabled allergists to identify the most common allergens, and also to determine what foods, ingredients and additives do not cause allergic reactions. |
Myth: I don't frequently eat food I'm allergic to, so I can eat a little bit for a special occasion.
Reality: Because food allergy can be life threatening, the allergen must be completely avoided-even the most minute amounts. Although an extreme case, a man allergic to shellfish died of anaphylaxis shock after encountering simply the steam from shrimp. It can be fatal to assume a given food environment is safe and not be cautious. A board-certified allergist can help the food allergic patient manage diet issues without sacrificing nutrition or pleasure when eating at and away from home. Since most life threatening, and sometimes fatal, allergic reactions to foods occur when eating away from home, it is imperative that the food allergic individual or responsible guardian clearly explain the risks of exposure to a certain food or ingredient to food service workers, family and friends-and always ask before eating.
Myth: With all the ingredients in processed food I can never completely avoid my allergen.
Reality: When purchasing groceries, labels should be read for every product purchased—every time. Although food and beverage manufacturers are often improving and changing their products, changes in ingredients must be listed on ingredient labels.
According to Fred Shank, Ph.D., director of the Center for Food Safety and Applied Nutrition, Food and Drug Administration (FDA), "Foods which contain allergenic substances must be properly labeled or be subject to recall. The FDA supports the activities of independent organizations to inform consumers of these recall activities." The FDA includes on its list of recall substances all eight of the major allergens, so if these substances are present in a food, but not listed on the label, they must be recalled. Additionally, substances which cause non-allergic-based reactions, such as the additives sulfites and tartrazine (FD&C Yellow #5), are on this list. Some individuals have unique sensitivities to these food components which are not allergenic or allergy-causing in nature, but may cause comparably severe reactions.
What is Sulfite Sensitivity?
Sulfiting agents are commonly used to preserve the color of foods, such as dried fruits and vegetables, and to inhibit the growth of microorganisms in fermented foods, like wine. Sulfites can also be found in beer, some fruit drinks, shrimp and some prepared foods. Although sulfites are safe for the majority of people, for some, they have been found to cause a reaction. For this reason, the FDA requires that when sulfites are added to foods in greater than 10 parts/million (or, 10 sulfite molecules per million molecules) they must be indicated on the label. |
Myth: Since I'm allergic to peanuts, I can't eat anything with peanut oil.
Reality: There are many misunderstandings regarding exactly what might stimulate the food allergic reaction. "Virtually all food allergens are proteins," explained Steve L. Taylor, Ph.D., co-director of the Food Allergy Research and Resource Program at the University of Nebraska-Lincoln. "And, the process of refining oil removes the protein which would trigger an allergic reaction." Oils used in processed foods and in cosmetics are highly refined and should pose no problem for the food allergic individual. Yet, caution should be taken with natural, cold pressed or flavored oils. These oils, as well as oil that has been used to cook peanuts (or another food to which an individual might have an allergy), might contain the protein of the allergen and should be avoided. For example, an individual with a fish allergy should ensure that the oil used to cook his or her food was not first used to fry fish.
Myth: I'm allergic to food additives.
Reality: Other common misconceptions regarding food allergy are additives and preservatives. Although some -- sulfites and tartrazine—have been shown to trigger asthma or hives in certain people, these reactions do not follow the same pathway observed with food. There are other food additives that have historically been associated with adverse reactions, but because they do not contain proteins or involve the immune system, true allergic pathways cannot be used to explain the reported reactions. In addition, many of these additives, including monosodium glutamate, aspartame and most food dyes have been studied extensively, and the results show little scientific evidence exists to suggest they cause any reaction at all.
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Avoid Cross Contact!
Cross contact of foods with those that may present a food allergy problem is poorly understood and not well communicated. Although food processors are well aware of the dangers of cross contact and manage them appropriately, such caution is not always taken in the home, school cafeteria or restaurant. Although unintentional, the effects can be devastating. For some food allergic individuals, the most minute particle of the allergen can be fatal. Some examples of mishaps that can induce a food allergic reaction include:
- Plain chocolate brownies are served using the same spatula that was used to serve peanut-containing brownies.
- French fries are prepared in the same oil used to deep-fry fish.
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Myth: "Tell me about my corn allergy."
Reality: There are those suspected food allergies that are so rare that their existence is questioned. The most common of these are corn and chocolate "allergy," and there are several probable explanations for adverse reactions. Even though many people claim to be allergic to them, allergists can rarely demonstrate allergy to corn or chocolate in double-blind, placebo-controlled food challenges (see sidebar).
Corn "allergy" is often associated with a reaction to another allergenic substance. In some cases soy allergic individuals may react to products containing corn. Occasionally corn is carried, handled or stored in the same containers used for soy. Although only minute residues of soy may remain, this can be enough to cause an allergic reaction in highly sensitive people.
Chocolate "allergy" is also thought to be extremely rare, and though some are truly chocolate-allergic, most who complain of symptoms have irreproducible reactions. Possibly the reactions are due to another ingredient found in the chocolate product being consumed.
Food allergy is certainly nothing to be taken lightly. Although its prevalence appears to be increasing, overreaction, self-diagnosis and incorrect assumptions only lead to skepticism of physicians and food service workers—obviously, a less-than-ideal situation for the truly allergic individual. It is vitally important to leave the diagnosis of a food allergy to a board-certified allergist.
The following organizations can help you more fully understand food allergy: The American Academy of Allergy, Asthma and Immunology (1-800-822-2762; www.aaaai.org) and the Food Allergy Network (1-800-929-4040; www.foodallergy.org). The International Food Information Council Foundation (http://ific.org) can provide further information on food allergy and food and asthma. Also available is a food allergy poster designed for food service workers.
