Let's Talk Nutrition

Allergies – Part II: Defining Terms Used

To Talk About Allergies

Michael Garko, Ph.D.

Host – Let’s Talk Nutrition

Allergies are the sixth leading cause of chronic disease affecting annually more than 50 million Americans and costing the healthcare system more than eighteen billion dollars (American Academy of Allergy, Asthma & Immunology, 2000).

When it comes to allergies, there is considerable terminological confusion about allergies among the general public, researchers, healthcare professionals and even people suffering from allergies. Although it may seem a bit elementary, an important first step in having an accurate and complete understanding of what allergies are and how they work is to know the meaning of a few basic terms related to allergies.

The November, 2007, issue of Healthful Hints devotes attention to defining a few important terms used frequently and sometimes inconsistently in the literature to describe and explain allergies and the allergic process.

This current issue continues the discussion on allergies from Allergies – Part I: An Introduction. It is recommended readers review Part I for some basic information on allergies with a specific focus on exposure to and common sources of substances (i.e., allergens) triggering an allergic response.

Terminology

Allergen

Allergens are substances (e.g., pollen, mold spores, animal danders, dust, foods, insect venoms & drugs) typically harmless to most people but capable of producing an adverse immune response in others. The term “allergen” is used variously in the literature to refer to the source of an allergy-producing substance such as biological sources (e.g., pets, insects, dust mites, plants and bacteria) and chemical sources (e.g., gases or particles released from building materials, fabrics, glues, paints, solvents, dyes, perfumes, etc.). “Allergen” is also used to mean the allergy-producing substance itself (e.g., dust mite & cockroach feces, pollens, molds, fungi & animal danders) and proteins that constitute the allergy-producing substance and trigger an immune response (e.g., see American Academy of Allergy, Asthma & Immunology, 2000; Wisconsin Department of Health & Family Services, 2007).

Allergy

According to the AAAI, an allergy is “an acquired potential to develop immunologically mediated adverse reactions to normally innocuous substances upon re-exposure to the sensitizing allergen (including IgE antibody responses to allergens), causing the release of inflammatory mediators (American Academy of Allergy, Asthma & Immunology, 2000, p. 91).

Allergic Diseases

Epidemiologically speaking, according to the AAAI (2000), allergic diseases are clinical manifestations of adverse immune responses caused by and following repeated contact with what is usually considered to be harmless substances such as pollens, molds, fungi, animal dander, house dust mite feces, cockroach feces, foods, insect venoms, latex, plants, cosmetics and drugs. There two general categories of allergic diseases. First, there are those allergic diseases which are termed atopic diathesis and include the specific diseases of allergic rhinitis, asthma and atopic dermatitis. Second, there are those allergic diseases which are considered to have an allergic component and include rhinitis, conjunctivitis, asthma, dermatitis, urticaria (hives) and anaphylaxis (see American Academy of Allergy, Asthma & Immunology, 2000).

Atopy

The concept of atopy implicates heredity and its role in developing allergies. The AAAI defines atopy as “the genetic tendency to develop the ‘classical’ allergic diseases, namely, allergic rhinitis, asthma, and atopic dermatitis” (American Academy of Allergy, Asthma & Immunology, 2000, p. 92). The AAAI (2000) goes on to say that “atopy is typically associated with a genetically determined capacity to mount IgE responses to common allergens, especially inhaled allergens and food allergens” (p. 92). The AAAI (2000) is careful to point out that the terms “allergy” and “atopy” are not synonyms. While atopy is used to mean that a person possess the potential to develop allergies due to an inherited hyperresponsiveness to allergens triggering asthma, allergic rhinitis (i.e., hay fever) and atopic dermatitis, an allergy signifies a person’s hypersensitivity to sensitizing allergens responsible for the release of inflammatory mediators.

Conclusion

The goal of the November issue of Healthful Hints was to provide readers with some clarity on terms used frequently in the scholarly and popular literature to describe and explain allergies. Knowing the meaning of the terms used to talk about allergies is a prerequisite to understanding how allergies work and how to prevent, treat and manage them. 

Providing a clear understanding of the terms “allergen,” “allergy,” “allergic diseases” and “atopy” will hopefully contribute to a clear discussion and understanding of allergies in the Healthful Hints series on this important topic. Upcoming issues will explore exactly how allergies work, types of allergies (e.g., airborne & food allergies), along with the prevention, treatment and management of allergies.

References

American Academy of Allergy, Asthma & Immunology (2000). The allergy report. Volume 1 Overview of allergic diseases: Diagnosis, management, and barriers to care. Milwaukee, Wisconsin.

Wisconsin Department of Health and Family Services (n.d.) Indoor allergens. Retrieved October 2, 2007, from http://dhfs.wisconsin.gov/eh/Air/fs/Allergens.htm