Table of Contents

f221 Coffee Scientific Information Summary Allergen Epidemiology Clinical Relevance Molecular Aspects Compiled By

Whole Allergen

f221 Coffee

f221 Coffee Scientific Information

Type:

Whole Allergen

Display Name:

Coffee

Route of Exposure:

Ingestion

Family:

Rubiaceae

Species:

Coffea arabica Coffea canephora Coffea liberica

Latin Name:

Coffea arabica, Coffea canephora

Summary

Coffee comes from roasted seeds of trees of the Rubiaceae family. It is consumed by hundreds of millions of people worldwide due to its pleasant taste, aroma, stimulant effect and health benefits. Allergy to coffee consumption is rare, and the few clinical cases reported are likely due to other ingredients contained in the beverage, rather than to the coffee bean itself. However, in processing the 9 million tons of coffee produced each year, many coffee workers are exposed to irritating and sensitizing dust. This represents a common occupational allergy and some cases are attributable to coffee bean dust in particular.

Allergen

Nature

Coffee is one of the most widely consumed beverages throughout the world due to its pleasant taste, aroma, stimulant effect and health benefits (1). The coffee beverage comes from roasted seeds of trees belonging to the Rubiaceae family and the genus Coffea. Coffee plants were discovered in Africa and eventually disseminated to countries around the world, with most of the production now coming from Brazil (2, 3). Currently, there are over 100 species within the genus Coffea although only two species are actually of importance in the world market: C. arabica and C. canephora (2). The coffee bean is the seed of the coffee plant and the world’s primary source of caffeine (1).

Taxonomy

Taxonomic tree of Coffee (4)
Domain	Eukaryote
Kingdom	Plantae
Phylum	Tracheophyta
Subphylum	Spermatophytina
Class	Magnoliopsida
Family	Rubiaceae
Genus	Coffee.

Taxonomic tree of Coffee (4)

Epidemiology

Worldwide distribution

Allergic reactions to the ingestion of coffee are appear to be rare and the results of the association between coffee consumption and asthma is inconsistent (5, 6).

Coffee is consumed by hundreds of millions people worldwide with about 9 million tons being processed every year. The processing includes removing pulps and drying the resulting green coffee beans by sunlight. Usually the beans are then roasted and/or decaffeinated and shipped worldwide. About 25 million coffee workers are exposed during the coffee processing to irritating and sensitizing dust with several additional allergens (including burlap and cockroach). Dust from coffee bean processing has been reported to elicit skin, ocular, and respiratory allergic reactions in up to 50% of coffee processing industry workers (7).

Clinical Relevance

Allergic reactions to the ingestion of coffee are rare and several studies indicate a beneficial effect in some asthmatic patients (5, 6). Case reports of allergic symptoms after coffee consumption have been attributed to other constituents, such as the preservative sodium metabisulphite (8), and to cow’s milk and/or sodium caseinate (9).

Allergic symptoms to caffeine have been reported in a small number of patients after consumption of coffee (10). Despite a lack of clinical reports investigating coffee allergy, one study including 150 people from Iraq showed that 25.7 % had positive coffee skin prick tests (11).

Molecular Aspects

Allergenic molecules

Table adapted from Allergome.org (12).

Allergen	Source
Cof a [Leaf]	Coffea arabica, Coffee, Plants, Rubiaceae
Cof a [Seed]	Coffea arabica, Coffee, Plants, Rubiaceae
Cof a 1	Coffea arabica, Coffee, Plants, Rubiaceae
Cof a 1.0101	Coffea arabica, Coffee, Plants, Rubiaceae
Cof a 2	Coffea arabica, Coffee, Plants, Rubiaceae
Cof a 2.0101	Coffea arabica, Coffee, Plants, Rubiaceae
Cof a 3	Coffea arabica, Coffee, Plants, Rubiaceae
Cof a 3.0101	Coffea arabica, Coffee, Plants, Rubiaceae

Allergen	Source

The first allergen isolated from Coffea arabica was a class III chitinase with a molecular weight of 32 kDa (Cof a 1), which was identified in 3 out of 17 symptomatic coffee workers (18%) (13). Cof a 2 and Cof a 3 (9 and 7 kDa, respectively) are two cysteine-rich metallothioneins that have also been identified as coffee allergens. In a screening of 18 symptomatic coffee workers 8 (44%) had serum IgE antibodies to one of the two allergens (7, 14).

Cross-reactivity

One study examined the cross-reactivity between extracts of various coffee beans and dust as well as with castor bean, which is another suspected allergen in the coffee processing industry. However no evidence of cross-reactivity was found with the roasted coffee beans (15).

Compiled By

Author: RubyDuke Communications

Reviewer: Dr. Michael Thorpe

Last reviewed:January 2022

References

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