Allergies Sourcebook, Seventh Edition

By Omnigraphics

Provides basic consumer health information about causes, triggers, and treatment of allergic disorders, along with coping strategies and prevention tips. Includes index, glossary of related terms, and other resources.

• Language: English
• Publisher: Omnigraphics
• Release date: Jul 1, 2022
• ISBN: 9780780819993

Book preview

Preface

About This Book

Allergy is a medical term that is used when a person’s immune system reacts abnormally to any foreign substance which is called an allergen. Allergies are classified into three types—mild, moderate, and severe. They are the sixth leading cause of chronic illness in the United States and it is the most common health issue affecting children in the United States. According to the statistics provided by the Centers for Disease Control and Prevention (CDC), more than 50 million people have allergies including indoor/outdoor allergies, food and drug, latex, insect, skin, and eye allergies.

Allergies Sourcebook, Seventh Edition provides information on various forms of allergies, their management, and how to avoid triggers and prevent symptoms. It offers a basic understanding of the immune system, the allergic reactions such as sinusitis, asthma, eczema, and anaphylaxis, and the allergens that cause them. It briefs out the common allergic triggers in food, air, environment, and chemicals along with managing allergies using medications, such as antihistamines, corticosteroids, anti-immunoglobulin E therapy, and allergy shots. The book concludes with the preventive methods to avoid allergies and their triggers along with a glossary of terms related to allergies and the immune system and directories of organizations to provide more information about allergies.

How to Use This Book

This book is divided into parts and chapters. Parts focus on broad areas of interest. Chapters are devoted to single topics within a part.

Part 1: Allergies and the Immune System: An Overview offers information on the basics of the immune system, how allergies occur, the common allergens and irritants such as cosmetics and biological contaminants along with details on early exposure and allergy prevention.

Part 2: An Overview of Allergic Reactions describes the various types of allergies including hay fever, sinusitis, asthma, eczema, contact dermatitis, and skin reactions. This part also discusses anaphylaxis and its link with red-meat allergy, exercise, and abnormal immune cells.

Part 3: Foods and Food Additives That Trigger Allergic Reactions provides the basic differences in food allergies and food intolerance. It also gives detailed information on various food allergies such as milk, egg, seafood, wheat, soy, and peanut allergy along with diagnosis and tips on avoiding food allergy reactions.

Part 4: Airborne, Chemical, and Other Environmental Allergy Triggers details allergies caused by various allergens such as pollen, dust mites, pets, lanolin, formaldehyde, and mold along with information on allergies caused by climatic changes, insect bites, and stings, and medicines such as penicillin and other vaccinations.

Part 5: Managing Allergies talks about the various allergy tests such as feeding tests, allergy blood tests, allergenics, elimination diet, including allergy medications such as antihistamines, decongestants, corticosteroids, and leukotriene modifiers. It also details complementary health approaches and therapies to treat and manage allergies.

Part 6: Avoiding Allergy Triggers and Preventing Symptoms discusses on improving indoor air quality, cleaning up mold, and controlling seasonal allergies. It provides information on preventing food allergies during pregnancy and while traveling including tips to avoid skin allergies while using cosmetics, perfumes, nail care products, face painting, and tattoos.

Part 7: Additional Help and Information consists of a glossary of terms related to allergies and the immune system along with directories or organizations and websites that provide information about allergies.

Bibliographic Note

This volume contains documents and excerpts from publications issued by the following U.S. government agencies: Agency for Toxic Substances and Disease Registry (ATSDR); Centers for Disease Control and Prevention (CDC); Climate.gov; Effective Health Care Program; Foodsafety.gov; Genetic and Rare Diseases Information Center (GARD); MedlinePlus; National Center for Biotechnology Information (NCBI); National Center for Complementary and Integrative Health (NCCIH); National Heart, Lung, and Blood Institute (NHLBI); National Institute for Occupational Safety and Health (NIOSH); National Institute of Allergy and Infectious Diseases (NIAID); National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK); National Institute of Environmental Health Sciences (NIEHS); National Institutes of Health (NIH); News and Events; NIH News in Health; Occupational Safety and Health Administration (OSHA); Office on Women’s Health (OWH); United States Access Board; U.S. Department of Veterans Affairs (VA); U.S. Environmental Protection Agency (EPA); and U.S. Food and Drug Administration (FDA).

It also contains original material produced by Infobase and reviewed by medical consultants.

About the Health Reference Series

The Health Reference Series is designed to provide basic medical information for patients, families, caregivers, and the general public. Each volume provides comprehensive coverage on a particular topic. This is especially important for people who may be dealing with a newly diagnosed disease or a chronic disorder in themselves or in a family member. People looking for preventive guidance, information about disease warning signs, medical statistics, and risk factors for health problems will also find answers to their questions in the Health Reference Series. The Series, however, is not intended to serve as a tool for diagnosing illness, in prescribing treatments, or as a substitute for the physician–patient relationship. All people concerned about medical symptoms or the possibility of disease are encouraged to seek professional care from an appropriate health-care provider.

A Note about Spelling and Style

Health Reference Series editors use Stedman’s Medical Dictionary as an authority for questions related to the spelling of medical terms and The Chicago Manual of Style for questions related to grammatical structures, punctuation, and other editorial concerns. Consistent adherence is not always possible, however, because the individual volumes within the Series include many documents from a wide variety of different producers, and the editor’s primary goal is to present material from each source as accurately as is possible. This sometimes means that information in different chapters or sections may follow other guidelines and alternate spelling authorities. For example, occasionally a copyright holder may require that eponymous terms be shown in possessive forms (Crohn’s disease vs. Crohn disease) or that British spelling norms be retained (leukaemia vs. leukemia).

Medical Review

Infobase contracts with a team of qualified, senior medical professionals who serve as medical consultants for the Health Reference Series. As necessary, medical consultants review reprinted and originally written material for currency and accuracy. Citations including the phrase Reviewed (month, year) indicate material reviewed by this team. Medical consultation services are provided to the Health Reference Series editors by:

Dr. Vijayalakshmi, MBBS, DGO, MD

Dr. Senthil Selvan, MBBS, DCH, MD

Dr. K. Sivanandham, MBBS, DCH, MS (Research), PhD

Health Reference Series Update Policy

The inaugural book in the Health Reference Series was the first edition of Cancer Sourcebook published in 1989. Since then, the Series has been enthusiastically received by librarians and in the medical community. In order to maintain the standard of providing high-quality health information for the layperson the editorial staff felt it was necessary to implement a policy of updating volumes when warranted.

Medical researchers have been making tremendous strides, and it is the purpose of the Health Reference Series to stay current with the most recent advances. Each decision to update a volume is made on an individual basis. Some of the considerations include how much new information is available and the feedback we receive from people who use the books. If there is a topic you would like to see added to the update list, or an area of medical concern you feel has not been adequately addressed, please write to: [e-mail].

Part 1 | Allergies and the Immune System: An Overview

Chapter 1 | Understanding the Basics of the Immune System

Function of Immune System

The overall function of the immune system is to prevent or limit infection. An example of this principle is found in immune-compromised people, including those with genetic immune disorders, immune-debilitating infections such as human immunodeficiency virus (HIV), and even pregnant women, who are susceptible to a range of microbes that typically do not cause infection in healthy individuals.

The immune system can distinguish between normal, healthy cells and unhealthy cells by recognizing a variety of danger cues called danger-associated molecular patterns (DAMPs). Cells may be unhealthy because of infection or because of cellular damage caused by noninfectious agents such as sunburn or cancer. Infectious microbes such as viruses and bacteria release another set of signals recognized by the immune system called pathogen-associated molecular patterns (PAMPs).

When the immune system first recognizes these signals, it responds to address the problem. If an immune response cannot be activated when there is sufficient need, problems arise, such as an infection. On the other hand, when an immune response is activated without a real threat or is not turned off once the danger passes, different problems arise, such as allergic reactions and autoimmune disease.

The immune system is complex and pervasive. There are numerous cell types that either circulate throughout the body or reside in a particular tissue. Each cell type plays a unique role, with different ways of recognizing problems, communicating with other cells, and performing their functions. By understanding all the details behind this network, researchers may optimize immune responses to confront specific issues, ranging from infections to cancer.

Location of Immune Cells

All immune cells come from precursors in the bone marrow and develop into mature cells through a series of changes that can occur in different parts of the body.

Skin. The skin is usually the first line of defense against microbes. Skin cells produce and secrete important antimicrobial proteins, and immune cells can be found in specific layers of skin.

Bone marrow. The bone marrow contains stems cells that can develop into a variety of cell types. The common myeloid progenitor stem cell in the bone marrow is the precursor to innate immune cells—neutrophils, eosinophils, basophils, mast cells, monocytes, dendritic cells, and macrophages—that are important first-line responders to infection.

Lymphoid progenitor. This stem cell leads to adaptive immune cells—B cells and T cells—that are responsible for mounting responses to specific microbes based on previous encounters (immunological memory). Natural killer (NK) cells also are derived from the common lymphoid progenitor and share features of both innate and adaptive immune cells, as they provide immediate defenses such as innate cells but also may be retained as memory cells such as adaptive cells. The B, T, and NK cells also are called lymphocytes.

Bloodstream. Immune cells constantly circulate throughout the bloodstream, patrolling for problems. When blood tests are used to monitor white blood cells, another term for immune cells, a snapshot of the immune system is taken. If a cell type is either scarce or overabundant in the bloodstream, this may reflect a problem.

Thymus. T cells mature in the thymus, a small organ located in the upper chest.

Lymphatic system. The lymphatic system is a network of vessels and tissues composed of lymph, an extracellular fluid, and lymphoid organs, such as lymph nodes. The lymphatic system is a conduit for travel and communication between tissues and the bloodstream. Immune cells are carried through the lymphatic system and converge in lymph nodes, which are found throughout the body.

Lymph nodes. They are a communication hub where immune cells sample information brought in from the body. For instance, if adaptive immune cells in the lymph node recognize pieces of a microbe brought in from a distant area, they will activate, replicate, and leave the lymph node to circulate and address the pathogen. Thus, doctors may check patients for swollen lymph nodes, which may indicate an active immune response.

Spleen. The spleen is an organ located behind the stomach. While it is not directly connected to the lymphatic system, it is important for processing information from the bloodstream. Immune cells are enriched in specific areas of the spleen, and upon recognizing blood-borne pathogens, they will activate and respond accordingly.

Mucosal tissue. Mucosal surfaces are prime entry points for pathogens, and specialized immune hubs are strategically located in mucosal tissues such as the respiratory tract and gut. For instance, Peyer patches are important areas in the small intestine where immune cells can access samples from the gastrointestinal tract.

Features of an Immune Response

An immune response is generally divided into innate and adaptive immunity. Innate immunity occurs immediately, when circulating innate cells recognize a problem. Adaptive immunity occurs later, as it relies on the coordination and expansion of specific adaptive immune cells. Immune memory follows the adaptive response, when mature adaptive cells, highly specific to the original pathogen, are retained for later use.

Innate Immunity

Innate immune cells express genetically encoded receptors, called toll-like receptors (TLRs), which recognize general danger-or pathogen-associated patterns. Collectively, these receptors can broadly recognize viruses, bacteria, fungi, and even noninfectious problems. However, they cannot distinguish between specific strains of bacteria or viruses.

There are numerous types of innate immune cells with specialized functions. They include neutrophils, eosinophils, basophils, mast cells, monocytes, dendritic cells, and macrophages. Their main feature is the ability to respond quickly and broadly when a problem arises, typically leading to inflammation. Innate immune cells also are important for activating adaptive immunity. Innate cells are critical for host defense, and disorders in innate cell function may cause chronic susceptibility to infection.

Adaptive Immunity

Adaptive immune cells are more specialized, with each adaptive B or T cell bearing unique receptors, B-cell receptors (BCRs) and T-cell receptors (TCRs), that recognize specific signals rather than general patterns. Each receptor recognizes an antigen, which is simply any molecule that may bind to a BCR or TCR. Antigens are derived from a variety of sources including pathogens, host cells, and allergens. Antigens are typically processed by innate immune cells and presented to adaptive cells in the lymph nodes.

The genes for BCRs and TCRs are randomly rearranged at specific cell maturation stages, resulting in unique receptors that may potentially recognize anything. Random generation of receptors allows the immune system to respond to new or unforeseen problems. This concept is especially important because environments may frequently change, for instance when seasons change or a person relocates, and pathogens are constantly evolving to survive. Because BCRs and TCRs are so specific, adaptive cells may only recognize one strain of a particular pathogen, unlike innate cells, which recognize broad classes of pathogens. In fact, a group of adaptive cells that recognize the same strain will likely recognize different areas of that pathogen.

If a B or T cell has a receptor that recognizes an antigen from a pathogen and also receives cues from innate cells that something is wrong, the B or T cell will activate, divide, and disperse to address the problem. B cells make antibodies, which neutralize pathogens, rendering them harmless. T cells carry out multiple functions, including killing infected cells and activating or recruiting other immune cells. The adaptive response has a system of checks and balances to prevent unnecessary activation that could cause damage to the host. If a B or T cell is autoreactive, meaning its receptor recognizes antigens from the body’s own cells, the cell will be deleted. Also, if a B or T cell does not receive signals from innate cells, it will not be optimally activated.

Immune memory is a feature of the adaptive immune response. After B or T cells are activated, they expand rapidly. As the problem resolves, cells stop dividing and are retained in the body as memory cells. The next time this same pathogen enters the body, a memory cell is already poised to react and can clear away the pathogen before it establishes itself.

Vaccination

Vaccination, or immunization, is a way to train your immune system against a specific pathogen. Vaccination achieves immune memory without an actual infection, so the body is prepared when the virus or bacterium enters. Saving time is important to prevent a pathogen from establishing itself and infecting more cells in the body.

An effective vaccine will optimally activate both innate and adaptive responses. An immunogen is used to activate the adaptive immune response so that specific memory cells are generated. Because BCRs and TCRs are unique, some memory cells are simply better at eliminating the pathogen. The goal of vaccine design is to select immunogens that will generate the most effective and efficient memory response against a particular pathogen. Adjuvants, which are important for activating innate immunity, can be added to vaccines to optimize the immune response. Innate immunity recognizes broad patterns, and without innate responses, adaptive immunity cannot be optimally achieved.

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This chapter contains text excerpted from the following sources: Text beginning with the heading Function of Immune System is excerpted from Overview of the Immune System, National Institute of Allergy and Infectious Diseases (NIAID), December 30, 2013. Reviewed April 2022; Text under the heading Features of an Immune Response is excerpted from Features of an Immune Response, National Institute of Allergy and Infectious Diseases (NIAID), January 16, 2014. Reviewed April 2022.

Chapter 2 | How Allergies Occur

Allergies are the reaction of the body’s immune system toward foreign substances, such as pollen, dust, and certain types of foods. The substances that trigger allergies are known as allergens.

How Do People Develop Allergies?

The immune system of our bodies produces antibodies to protect us from illnesses. If allergens enter our body, our immune system makes immunoglobulin E (IgE) to assist in combating the allergy symptoms. Hence, an allergic person will have high IgE levels toward exposure to allergens.

The immune system develops immunological memory over time, enabling the body to respond more quickly. So, repeated exposure to allergens causes recurrent overreactions of the immune system. As a result, people exposed to allergens may experience allergic reactions, such as sneezing, coughing, sniffling, congestion, and increased asthma symptoms.

Triggers of Allergic Reactions

The most common types of allergens are:

Pet dander

Pollen

Insect bites

Certain foods, such as nuts, wheat, soy, eggs, fish, and milk

Certain metals

Specific types of plants and trees

Dust mites

Stages of Allergic Reactions

Allergies are prevalent and range from mild to severe. People with allergies ought to know the typical stages of an allergic reaction, enabling them to respond accordingly.

Exposure to allergens. Exposure usually happens through inhalation, eating certain foods, touching objects, or biting. The reaction could occur within seconds after the allergen enters the body.

Early allergic reactions. The body triggers a response to get rid of or kill the allergen. Hence, the immune cells release mediators, such as histamine, to facilitate the capillaries for the white blood cells to attack the allergen.

Late allergic reactions. Late allergic reactions usually reach their peak six to nine hours after exposure to the allergen. The later symptoms include pain, swelling, skin redness, or labored breathing, and they typically subside within a day or two.

Types of Allergic Reactions

According to the British immunologists Coombs and Gell, allergic reactions are of four types.

Type I or Anaphylactic Reactions

The antibodies involved in type I are IgE and cause inflammation and swelling.

Type I allergic reactions include:

Allergic rhinitis

Allergic dermatitis

Bronchial asthma

Allergic conjunctivitis (eye inflammation)

Anaphylaxis (allergic shock)

Type II or Cytotoxic Reactions

The antibodies involved in type II are IgG and IgM. This will damage the cells by activating the complement system, a component of immunity.

Type II allergic reactions can occur under certain conditions:

Autoimmune hemolytic anemia

Immune thrombocytopenia

Autoimmune neutropenia

Type III or Immune Complex Reactions

The same antibodies in type II (IgM and IgG) mediate the type III reactions. But, in type III, IgM and IgG antibodies react with the allergen to form immuno complexes, a molecule formed from the binding of multiple antigens to antibodies.

Type III allergic reactions can occur under certain conditions:

Lupus

Serum sickness

Arthus reaction

Type IV or Cell-Mediated Reactions

Type IV allergic reactions, also known as a delayed type of hypersensitivity or allergic reactions, will occur after at least 24 hours and at most 48–72 hours of exposure to the allergen.

Type IV allergic reactions can be seen in certain conditions:

Tuberculosis

Fungal infections

Though it is difficult to understand why one person develops an allergic reaction while others do not, an allergy is a permanent condition that can only be controlled and not cured completely. People who are allergic must take certain precautions and steps to ensure that they stay away from allergens as much as possible.

References

Allarakha, Shaziya. MD, What Are the Four Types of Allergic Reactions? MedicineNet, March 4, 2022.

Allergy Overview, Cleveland Clinic, November 30, 2020.

Stages of Allergic Reactions to Know, Oak Brook Allergists, August 27, 2021.

What Causes a Person to Develop Allergies Carolina Asthma & Allergy Center P.A., March 16, 2022.

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How Allergies Occur, © 2022 Infobase. Reviewed April 2022.

Chapter 3 | Genetics of Allergic Diseases

The National Center for Biotechnology Information (NCBI) understanding of the specific genetic lesions in allergy has improved in the years due to identification of common risk variants from genome-wide association studies (GWAS) and studies of rare, monogenic diseases. Large-scale GWAS have identified novel susceptibility loci and provided information about shared genetics between allergy, related phenotypes and autoimmunity. Studies of monogenic diseases have elucidated critical cellular pathways and protein functions responsible for allergy. These complementary approaches imply genetic mechanisms involved in Th2 immunity, T-cell differentiation, TGFβ signaling, regulatory T-cell function and skin/mucosal function as well as yet unknown mechanisms associated with newly identified genes. Future studies, in combination with data on gene expression and epigenetics, are expected to increase the NCBI understanding of the pathogenesis of allergy.

Allergy and related diseases are highly heritable, and the NCBI understanding of the specific genetic background has improved in the years due to identification of common risk variants from GWAS and increased understanding of rare, allergy-related monogenic diseases. Here, the NCBI reviews these two different approaches and their contribution to the field of allergy genetics.

Related Traits

Most allergy-related GWAS have investigated asthma with more than 35 studies registered to date. A large, consortium-based study identified six genome-wide significant loci, all of which have been confirmed in independent studies. The strongest associated asthma locus in this and other GWAS is located on chromosome 17q21. The disease-associated gene at this locus is still unclear with the earliest study pointing toward ORMDL3 while a later study using expression data from lung tissue pointed toward GSDMA. Proposed mechanisms of ORMDL3 include a role in sphingolipid synthesis and regulation of eosinophils. Two loci spanning IL33 and IL1RL1 (encoding an IL-33 receptor) respectively, imply an important role of IL-33-related airway inflammation in the pathogenesis of asthma. Other loci identified included the HLA region, SMAD3 and IL2RB, and more have been proposed from other GWAS on asthma and other allergy-related diseases, such as eczema (atopic dermatitis) and eosinophilic esophagitis. These highlight a number of potential pathogenetic mechanisms and pathways, mainly related to immune mechanisms and skin/mucosal barrier function.

Allergy and Allergic Sensitization

Asthma and eczema are associated with allergy but still many patients have these diseases without concurrent allergy, the so-called nonatopic phenotypes. Therefore, susceptibility loci for these diseases are not necessarily associated with allergic mechanisms. Only a few GWAS have specifically addressed allergy or allergic sensitization. The first large-scale study on allergic sensitization, the hallmark of allergic disease, was performed in 2013 by meta-analysis of data from 16 different studies. Allergic sensitization was assessed objectively and defined by elevated levels of allergen-specific IgE and/or a positive skin prick test. This study identified 10 loci associated with allergic sensitization at the genome-wide significant level and with robust replication. Simultaneously, a large GWAS was performed on allergic symptoms identifying 16 genome-wide significant loci. This study was based upon self-reported symptoms and a combination of allergic symptoms from different organ systems, including rhinitis, asthma and skin reactions. In spite of these phenotype differences, there was high agreement of results between the two studies. Previous GWAS findings on allergic rhinitis and sensitization were confirmed and together these studies increased the number of loci associated with allergy or allergic sensitization to 18. One of the strongest associated loci in both GWAS was on chromosome 11q13. The underlying mechanism is unclear, but this locus was associated with expression of the two nearby genes—C11orf30, a potential regulator of interferon-stimulated genes and viral immunity, and LRRC32, involved in TGFb signaling in regulatory T-cells (Tregs). The associated loci imply the importance of Th2 promoting/Th2 dominated immune mechanisms (STAT6, TSLP, BCL6, IL1RL1, IL33, GATA3), innate immunity (TLR1/6/10), TGFβ-signaling (LRRC32, SMAD3), T-cell (IL2, PTGER4) and Treg (LRRC32, IL2, NFATC2, FOXA1) differentiation and function in the pathogenesis of allergy.

Allergy and Autoimmunity

Allergy and autoimmune diseases are classically considered representatives of Th2 and Th1/Th17 driven immune responses, respectively, with counteracting immune mechanisms. Overlapping mechanisms are suggested by some studies of comorbidity suggesting inverse as well as direct relationships and by the parallel epidemic observed for allergy and autoimmune diseases in the last decades. The two GWAS on allergy and allergic sensitization demonstrated a large overlap between susceptibility loci for allergy and autoimmune diseases with 12 of the 18 genome-wide significant loci for allergy also encompassing variants associated with autoimmune diseases. Shared genetics are supported by a study showing that approximately 90 percent of variants associated with autoimmune diseases are noncoding, mapping to regulatory regions specifically active in immune cells, and that these are clustered closely together with asthma and allergy. Two examples of shared loci are the 11q13 locus, which showed strong association with several allergy-related diseases and was also among the strongest loci for inflammatory bowel disease, and the 17q21 asthma locus also associated with several autoimmune diseases, including type 1 diabetes and inflammatory bowel disease. Interestingly, the direction of effect was the same for allergy and autoimmune disease at the 11q13 locus but opposite at the 17q21 locus. Further understanding of these shared susceptibility loci may help elucidate the complex relationship and pathogenesis of allergy and autoimmune diseases.

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This chapter includes text excerpted from Genetics of Allergy and Allergic Sensitization: Common Variants, Rare Mutations, National Center for Biotechnology Information (NCBI), September 18, 2015. Reviewed April 2022.

Chapter 4 | Common Allergens and Irritants

Chapter Contents

Section 4.1—Allergens in Food and Consumer Products

Section 4.2—Allergens in Cosmetics

Section 4.3—Allergens and Biological Contaminants

Section 4.1 | Allergens in Food and Consumer Products

This section includes text excerpted from Food Allergies, U.S. Food and Drug Administration (FDA), March 31, 2022.

Food allergies and other types of food hypersensitivities affect millions of Americans and their families. Food allergies occur when the body’s immune system reacts to certain proteins in food. Food allergic reactions vary in severity from mild symptoms involving hives and lip swelling to severe, life-threatening symptoms, often called anaphylaxis, that may involve fatal respiratory problems and shock. While promising prevention and therapeutic strategies are being developed, food allergies currently cannot be cured. Early recognition and learning how to manage food allergies, including which foods to avoid, are important measures to prevent serious health consequences.

To protect those with food allergies and other food hypersensitivities, the U.S. Food and Drug Administration (FDA) enforces regulations requiring companies to list ingredients on packaged foods and beverages. For certain foods or substances that cause allergies or other hypersensitivity reactions, there are more specific labeling requirements.

The FDA provides guidance to the food industry, consumers, and other stakeholders on the best ways to assess and manage allergen hazards in food. It also conducts inspections and sampling to check that major food allergens are properly labeled on products and to determine whether food facilities implement controls to prevent allergen cross-contact (the inadvertent introduction of a major food allergen into a product) and labeling controls to prevent undeclared allergens during manufacturing and packaging. When problems are found, the FDA works with firms to recall products and provide public notification to immediately alert consumers. In addition, the FDA has the authority to seize and remove violative products from the marketplace or refuse entry of imported products.

Major Food Allergens

Congress passed the Food Allergen Labeling and Consumer Protection Act of 2004 (FALCPA). This law identified eight foods as major food allergens: milk, eggs, fish, shellfish, tree nuts, peanuts, wheat, and soybeans.

On April 23, 2021, the Food Allergy Safety, Treatment, Education, and Research (FASTER) Act was signed into law, declaring sesame as the ninth major food allergen recognized by the United States. This change will become effective on January 1, 2023, so labeling sesame as an allergen will not be required until that time.

At the time of FALCPA’s passage, the eight major allergens accounted for 90 percent of food allergies and serious allergic reactions in the United States. FALCPA requires that foods or ingredients that contain a major food allergen be specifically labeled with the name of the allergen source. Congress passed this law to make it easier for consumers who are allergic to foods and their caregivers to identify and avoid foods that contain major food allergens. The FDA enforces the provisions of this law in most packaged food products. This includes dietary supplements but does not include meat, poultry, and egg products, which are regulated by the U.S. Department of Agriculture (USDA); alcoholic beverages subject to Alcohol and Tobacco Tax and Trade Bureau (TTB) labeling regulations; raw agricultural commodities; drugs; cosmetics; and most foods sold at retail or food service establishments that are not prepackaged with a label.

Food Labels and Allergens

People with food allergies should read labels and avoid the foods they are allergic to. The law requires that food labels identify the food source of all major food allergens used to make the food. This requirement is met if the common or usual name of an ingredient already identifies that allergen’s food source name (e.g., buttermilk). Otherwise, the allergen’s food source must be declared at least once on the food label in one of two ways.

The name of the food source of a major food allergen must appear:

In parentheses following the name of the ingredient (e.g., lecithin (soy), flour (wheat), and whey (milk)).

Immediately after or next to the list of ingredients in a contains statement (e.g., contains wheat, milk, and soy).

The FALCPA’s labeling requirements extend to retail and food-service establishments that package, label, and offer products for human consumption. However, FALCPA’s labeling requirements do not apply to foods that are placed in a wrapper or container (such as paper or a box for a sandwich) following a customer’s order at the point of purchase.

Consumers may also see advisory statements such as may contain (allergen) or produced in a facility that also uses (allergen). These are used to address cross-contact, which can occur when multiple foods with different allergen profiles are produced in the same facility using shared equipment or on the same production line, as the result of ineffective cleaning, or from the generation of dust or aerosols containing an allergen.

The FDA guidance for the food industry states that advisory statements should not be used as a substitute for adhering to current good manufacturing practices and must be truthful and not misleading.

Other Allergens or Allergenic Substances

More than 160 foods have been identified to cause food allergies in sensitive individuals. There are also several food ingredients that cause nonallergic hypersensitivity reactions in sensitive individuals that require specific labeling. For example, in addition to the eight major food allergens identified by law, the FDA monitors the food supply to determine if other allergens, food ingredients, or food additives pose a significant health risk and acts accordingly. Gluten, certain additives (e.g., yellow 5, carmine, sulfites), and other food allergens for which new science has emerged are examples of other substances the FDA monitors and, in some cases, require specific labeling for.

Gluten

Gluten describes a group of proteins found in certain grains (e.g., wheat, barley, and rye). In people with celiac disease, foods that contain gluten trigger an immune response that attacks and damages the lining of the small intestine. Such damage may not only limit the ability of celiac disease patients to absorb nutrients, leading to problems such as iron deficiency anemia, osteoporosis, and malnutrition, but it puts them at increased risk for potentially serious health problems, including intestinal cancers and autoimmune diseases such as diabetes. On August 2, 2013, the FDA issued a final rule defining gluten-free for food labeling, which helps consumers, especially those living with celiac disease, be confident that items labeled gluten-free meet a defined standard for gluten content. On August 12, 2020, the FDA issued a final rule to establish compliance requirements for fermented and hydrolyzed foods, or foods that contain fermented or hydrolyzed ingredients, bearing the gluten-free claim.

Color and Food Additives

Some individuals may have hypersensitivity reactions to a color additive. For example, FD&C Yellow No. 5, widely found in beverages, desserts, processed vegetables, drugs, makeup, and other products, may cause symptoms such as itching and hives in some people. The FDA requires all products containing FD&C Yellow No. 5 to identify it on their labels so consumers who are sensitive to the dye can avoid it. Color additives made from cochineal extract and carmine, which are derived from insects, have been identified as allergenic substances that must be declared on the label of all food and cosmetic products. Various sulfiting agents, including sodium bisulfite, are allowed as food ingredients. But, due in part to adverse reactions to them, such as asthma in sensitive individuals, they must be declared on food labels when present in food and the concentration in the food is ≥10 parts per million total sulfur dioxide.

Sesame

Under the FASTER Act of 2021, sesame is being added as the 9th major food allergen effective January 1, 2023. Until that time, manufacturers do not have to list it as an allergen, although in most cases it must appear in the ingredient statement. An exception is when sesame is part of a natural flavoring or spice. Another exception is when sesame is not in the common or usual name of a food (e.g., tahini, which is made from sesame seeds). In November 2020, to help consumers who are allergic or sensitive to sesame to avoid these products, the FDA issued a draft guidance to encourage manufacturers to voluntarily declare sesame in the ingredient list when it is used as a flavoring or spice or when the common or usual name (such as tahini) does not specify sesame. The guidance is intended to help protect consumers who are allergic to sesame by encouraging manufacturers to identify all ingredients that contain sesame right now.

What to Do If Symptoms of an Allergic Reaction Occur

Symptoms of food allergies typically appear from within a few minutes to a few hours after a person has eaten the food to which she or he is allergic. A severe, life-threatening allergic reaction is called anaphylaxis.

Symptoms of allergic reactions can include:

Flushed skin or rash.

Tingling or itchy sensation in the mouth.

Face, tongue, or lip swelling.

Vomiting and/or diarrhea.

Abdominal cramps.

Coughing or wheezing.

Dizziness and/or lightheadedness.

Swelling of the throat and vocal cords.

Difficulty breathing.

Loss of consciousness.

People with a known food allergy who begin experiencing any of