Type:
Whole Allergen
Whole Allergen
f93 Cacao
f93 Cacao Scientific Information
Display Name:
Cacao
Route of Exposure:
Ingestion
Family:
Malvaceae
Species:
Theobroma cacao
Latin Name:
Theobroma cacao
Other Names:
Cacao powder
Summary
Cacao (Theobroma cacao) is a small tree belonging to the Malvaceae family. Its seeds are used to make cocoa powder and chocolate which is consumed around the world. Cacao allergy can induce cutaneous, oral/gastrointestinal, respiratory symptoms, , and anaphylaxis after ingestion. Studies have shown that individuals working with cacao seeds are at risk of experiencing allergic reactions due to their allergen's inhalation. To date, no major cacao allergens have yet been recognized. The seed of this plant contains albumin 2S protein, which is associated with allergenicity. Cross-reactivity has been observed with chocolate, lupin, milk peanut, walnut, tree nut etc.
Allergen
Nature
The cacao plant has dimorphic branches with a distinct pattern. It grows up to a height of 1.5 meters. From this part, usually, three to five horizontal branches grow. They are known as fans. The fruit of cacao is known as a pod. On becoming mature, the fruit contains a broad husk that has about 30 to 50 seeds. These seeds are enveloped by a sugary coating known as pulp. (1). Cacao is a food of plant origin, commonly consumed as a beverage worldwide after coffee and tea. It is mainly utilized in the confectionery makings and is the principal component of the chocolates. The word "Cacao" was first given by the Spanish people, and it has its origin from the word "Cacahuatl," which Aztecs used for cacao beans. There is no fixed flowering season for cacao, and peaks occur during few months in a year. It depends on geography as well as environmental conditions. In Ghana, peak flowering occurs in May to June (1). There are plenty of species under the Theobroma genus. However, cacao is the one that is developed worldwide (2).
Habitat
Cacao plants grow well in the moderately high temperature ranging from 30º Celsius to 32ºCelsius as well as low temperatures ranging from 18º Celsius to 21º Celsius (2). Cacao can adjust to a wide variety of soils, particularly in Africa and Asia. Soil from virgin or recently cleared forest areas is quite suitable for the cultivation of this crop. Also, soil with pH from acidic to neutral, having abundant organic components with nitrogen is favored for cacao plant production. The cacao plant's growth mainly depends on environmental factors such as temperature and rain (1). This plant also needs an adequate number of additives to the soil. It can tolerate waterlogging for a short duration (2).
Taxonomy
| Taxonomic tree of Cacao (3) | |
|---|---|
| Domain | Eukaryota |
| Kingdom | Plantae |
| Phylum | Spermatophyta |
| Subphylum | Angiospermae |
| Class | Dicotyledonae |
| Order | Malvales |
| Family | Malvaceae |
| Genus | Theobroma |
| Species | Theobroma cacao |
| Taxonomic tree of Cacao (3) |
|---|
Tissue
The cacao plant seeds are known as cacao beans, which are the main parts of this plant used worldwide. These seeds are enveloped by a sugary coating known as pulp. The size of the cacao bean is of economic value. Particularly a minimum bean size of 1 g is generally considered as the standard. The number of beans per pod ranges from 30-60. The seed comprises two serpentine cotyledons, an embryo and a thin membrane, the remains of the endosperm, and a leathery shell. It is the main ingredient of chocolate. The other ingredients of chocolate can be milk and tree nuts (1). The cacao seed contains albumin 2S protein and is associated with allergenicity (4).
Epidemiology
Worldwide distribution
A survey was done in Central America in El Salvador to estimate the prevalence of parent-reported food allergy in school children. The study stated 4.3% of the reported food-related adverse reactions, and 0.78% said food allergen associated allergic reactions were commonly due to chocolate(5). A study was conducted in Russia, Estonia, Lithuania, Sweden, and Denmark to know the prevalence of self-reported hypersensitivity reactions to different foods. A total of 1139 patients were included. The result showed that 32% of patients had a chocolate allergy, whereas 15% had cocoa (cacao) allergy. In the eastern countries, food eliciting severe symptoms other than chocolate was found to be strawberry, hazelnut, milk, peanut and walnut while in western countries they were hazelnut, walnut, peanut, brazil nut, pistachio nut and milk. (6). A study was conducted in Turkey to know the prevalence of food-related adverse reactions in 6 to 9 years old (n=3500) children. The study showed that around 31.6% percent of the children were allergic to cocoa (cacao) among parental-reported allergies. Additionally, reports confirmed through skin prick tests, and food challenge tests showed around 14.7% and 18.1 %, respectively, were allergic to cocoa (cacao) (7).
Risk factors
In a study done on 71 confectionery workers, the results showed 31% of the workers had a positive reaction to skin test using cacao extract. The prevalence of asthma was 26.1% and dyspnoea 26.1% percent among these workers, which was considerably higher than other workers. (8).
Pediatric issues
A food allergy study was conducted in Finland on 866 children aged 1 to 6 years. The children selected in the study suffered from a skin rash or heavy vomiting after food intake. Among these 802 children with recent history information showed chocolate allergy through antigens against chocolate in 2% in children aged one year, 4% in children aged 2 and 3 years and 1% in children aged six years (9). A study in Turkey showed that in children, most reported allergies was to chocolate. Among these, cocoa was a common causing sensitization and the second most common food with milk (from cow) to cause IgE-mediated food allergic reactions. (7)
Environmental Characteristics
Worldwide distribution
Cacao is a tree originally from the northern and humid areas of the United States' north and central parts (1). The cacao plant is a tropical plant with its origin most probably from South America. After the 15th century, its cultivation has been extended to the regions such as Venezuela, Ecuador, Trinidad, and other areas of America. Currently, the western parts of Africa and Asia produce the world's highest cacao (10).
Route of Exposure
Main
Cacao allergy occurs mainly through the ingestion route (11).
Secondary
Also, the inhalation of cacao has been found to trigger asthma (11).
Clinical Relevance
Food can cause a reaction such as cutaneous, oral/gastrointestinal, respiratory symptoms, and generalized reactions, including fatal anaphylaxis (7)
Anaphylaxis
In a university in Spain, a study was conducted to analyze the intake of cocoa and students' health status. The results were grouped according to low (LC), moderate (MC), and high (HC) consumers of cocoa. Among 270 participants, 87 were cocoa intolerant. Among the groups, 28%, 13% and 19% were allergic to the LC, MC and HC group, respectively. Around 36% of these showed cutaneous reactions such as hives, redness or itching. Approximately 34% of the individuals developed symptoms like rhinitis, sneezing or mouth itching. Among these allergic patients, three of them, due to severe reaction, had to stay home for recovery(12).
Contact Urticaria
A study to investigate allergens causing acute urticaria in children was conducted in Iran. One hundred and twenty-nine children suffering from acute urticaria participated in the study. Among these, 11.6% were observed to show positive skin prick tests to cocoa. Studies have shown in some cases, following food avoidance treatment to children suffering from urticaria may cause malnutrition, developmental and behavioral disorders (13).
Gastrointestinal
A study in Mexico analyzing patients with food allergy reported 23% suffering from gastrointestinal symptoms, 38% with cutaneous rash, 15% with eczema and 17% with wheezing or cough. Among these patients, 8.3% were observed to have sensitization towards cocoa, 28% to milk, 6.6% to almonds and 5% to peanuts (14, 15).
Atopic Dermatitis
A study was done in Finland to know the prevalence of allergic reactions in 1120 atopic individuals with common spices using a scratch test. In these patients, atopic dermatitis was detected in about 50% of the patients. Around 2.2% showed positive skin tests to cocoa (16).
Allergic Rhinitis (AR) and Allergic Rhino Conjunctivitis (ARC)
A study was conducted in Turkey to know the prevalence of anamnestic food allergy in patients with seasonal allergic rhinitis. The results showed that around 1.2 percent of the patients (n =9) had an allergic reaction to cacao (17).
Asthma
A case was reported from Canada in which occupational asthma occurred due to cacao. A confectionary worker, aged 31 years, had a history of allergy (familial and personal). The worker developed symptoms such as nasal pruritus and congestion, rhinorrhoea, sneezing, shortness of breath, coughing and wheezing after coming in contact with cacao beans. The study stated these symptoms seemed to improve after removing his connection with the cacao beans during his work (11). In another study in confectionery workers, the prevalence of asthma was 26.1% percent in workers with positive skin prick tests. These positive results occurred with cacao, chocolate and cocoa extracts to 31%, 9%, and 6% of the workers, respectively (8).
Prevention and Therapy
Prevention strategies
Avoidance
The primary strategy to avoid cacao allergy is to completely abstain from such foods (4,7).
Molecular Aspects
Allergenic molecules
No major cacao allergens have been identified (4). A cacao seed protein 2S albumin has been determined, which is recognized to be in storage polypeptide is responsible for allergenicity (4). A particular gene produces a 67-kDa storage protein precursor of cacao. SDS–PAGE analysis has identified the presence of influential bands at 30and 44 kDa. These bands get damaged in the processes such as germination and fermentation. Another major cacao seed protein with a band of 21 kDa has also been identified (18).
Biomarkers of severity
The cacao seed albumin 2S is associated with allergenicity (4).
Cross-reactivity
Cross-reactivity has been found with patient serum consisting of chocolate and lupin extract (19). A minor allergen from walnut (vicilin family) shows about 90 percent similarity with cocoa (cacao) vicilin (20). Cacao has also been known to be cross-reactive with peanut, milk, tree nuts, and tobacco and ragweed. This cross-reactivity is mostly due to similar polyphenols haptens in these substances (4, 21).
Compiled By
Author: Turacoz Healthcare Solutions
Reviewer: Dr. Christian Fischer
Last reviewed: November 2020
References
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