The information in this website is intended only for healthcare professionals. By entering this site, you are confirming that you are a healthcare professional.
The information in this website is intended only for laboratory professionals. By entering this site, you are confirming that you are a laboratory professional.
|Route of Exposure||Ingestion|
|Source Material||Whole fresh fruit|
|Latin Name||Ananas comosus|
|Other Names||Ananas, Piña|
|Categories||Fruits, Food Of Plant Origin|
Ananas comosus, popularly known as pineapple belongs to the family of Bromeliaceae and is considered as the second most essential tropical fruit worldwide. The pineapple fruit is widely consumed fresh or cooked or even extracted for its juice. Consumption of pineapple has mostly been associated with allergic reactions, such as oral allergy syndrome (OAS), that may be related to pollens (pollen-food-syndrome). The OAS due to pineapple was found to be prevalent in various regions across the globe (Mexico, Europe, Africa, Asia and Australia), however, the percentage of prevalence was not found to be very significant. Such type of OAS (oropharyngeal, cutaneous, respiratory, or gastrointestinal manifestations) is attributed to the presence of pan-allergen profilin, Ana c 1 in pineapple fruit. Further, systemic immunoglobulin (Ig) E-mediated hypersensitivity reactions are also observed due to pineapple consumption, mainly due to its bromelain content (Ana c 2, a major allergen). Such reactions may even lead to anaphylaxis in few cases. Besides, pineapple has been found to be associated with unpleasant reactions, such as oral mucosal irritation, which is majorly due to its acidic content or bromelain-mediated proteolysis of oral mucosa, so not due to the IgE-mediated allergic reactions. Bromelain or Ana c 2 is a member of cysteine protease enzyme and plays a major role in detecting cross-reactive carbohydrate determinants (CCD) in pollens. Further, Ana c 1 is found to be cross-reactive with profilins present in pollens and fruits due to its high-sequence identity observed (Bet v 2, Phl p 12, Hev b 8, Mal d 4, Pru av 4, peanut, pear, and celery). Also, pineapple has been found to be associated with latex-fruit syndrome and ficus-fruit syndrome due to both its allergens, profilin and bromelain. Additionally, bromelain is highly homologous to other cysteine proteinases, such as papain.
Ananas comosus, popularly known as pineapple, belongs to the family of Bromeliaceae and is considered as the second most essential tropical fruit, after banana (1). It is widely consumed across the world due to its remarkable succulent nature, vivid flavor and for its nutritional value (2). Pineapple plant is a long-lasting herb that grows up to a height of about 1.5 m (3). The sword-shaped leaves (~80 leaves on a mature plant) are organized in spiral pattern on the cylindrical stem with flowers at the terminal end, developing into an edible fruit. This plant possesses both underground as well as aerial roots which are adventitious and help in vegetative propagation (1).
Pineapple has unique inflorescence with 50 to 200 bisexual flowers forming a thick bract with the leaves. The color of the bracts may change i.e., from lavender to purple to even red, based on its variety. The pineapple fruit is distinctive from other fruits as it is technically named as ‘sorosis’, meaning a multiple large fruit formed by fusion of many fruits together (coalesced berries). It is naturally produced without fertilization of ovules, making the fruit seedless. The outer skin of the fruit is hard and composed of hexagonal segments (called eyes), that are arranged in Fibonacci numbers (1, 3). Its color may vary from green to yellow to orangish-yellow to red during its maturation process (1).
Globally, it is either consumed fresh, or cooked or even extracted for its juice. It is used in wide variety of edible items, such as fruit salads, candies, syrups, yogurt, desserts, jam, beverages, vinegar, pineapple chips or its puree. Pineapples can also be preserved and used as canned products. The green pineapples are generally used for preparing pickles. Further, the soft leaves and the left-over after juice extraction is used for livestock feeding (2).
Pineapple is a fruit crop that prefers warm-humid condition, and hence grows well in tropical and subtropical zones of the hemisphere. This essential crop can grow at both sea level as well as at altitudes of >1400 m above sea level, that is devoid of cold icy climate (1, 4). The annual rainfall required for the favorable growth of the plant is between 760 and 1,000 mm, with the temperature ranging between 20 and 30℃. It grows best on sandy or clay loamy soil with an acidic pH and loaded with organic material and potassium (4).
The taxonomy of pineapple has evolved over several years and has now been simplified by classifying all the pineapples under one genus i.e., Ananas, which is further categorized into five different varieties. The edible pineapple constitutes of Ananas comosus var. comosus, while the others include var. microstachys, parguazensis, erectifolius and bracteatus (1).
The taxonomic tree of edible pineapple as accessed on February 19, 2021 is as below (5):
|Taxonomic tree of Pineapple (5)|
Pineapple fruit may induce immunoglobulin (Ig) E-hypersensitivity reactions with bromelain, a proteolytic enzyme and a major allergen of pineapple responsible for its allergy (6, 7). Apart from the fruit, bromelain has extensively been found in other parts of the plant, which include its stem, leaves as well as peel of the fruit. The stem and fruit possess high quantities of bromelain allergen, which has wide biotechnological applications in the field of food, medicine and cosmetic industry. Interestingly, the bromelain content in stem is more than that of fruit (8).
Consumption of pineapple has been associated with allergic reactions, such as oral allergy syndrome (OAS) that may be related to pollens (pollen-food-syndrome) and systemic IgE-mediated hypersensitivity reactions that may even result in anaphylaxis (6).
In a cross-sectional study conducted in Mexico that evaluated the prevalence of OAS among 267 children (age: 6-15 years), it was found that 24 of them (8.9%) were having OAS symptoms, of which 23 showed pollen food allergy syndrome (PFAS). Pineapple was considered as the most frequent food associated with OAS or PFAS (62.5%, 15 out of 24) (9).
In another cross-sectional study conducted in Africa, that evaluated the prevalence of food allergy among 1431 school children (age: 5-16 years), 2% of children (n=28) were found to be sensitive to pineapple based on skin prick test (SPT) using fresh pineapple (10).
A cohort study conducted in Denmark that evaluated the prevalence of food hypersensitivity among young adults (mean age: 22 years), self-reported secondary food hypersensitivity (food allergy-related to pollens) was observed in 141 out of 843 participants. Pineapple was found to be the cause of secondary food hypersensitivity in 4.4% of cases (11). Also, a study conducted in Germany found the history of immediate allergic reactions to pineapple in 19 out of 380 patients with PFAS (12).
A study conducted among 437 elementary school children in Korea reported the prevalence of food allergy in 86 children based on a questionnaire survey. The pineapple allergy was reported by only one child (13). While a nationwide cross-sectional, multicenter questionnaire-based study conducted in Korea among 270 PFAS patients, the pineapple was reported to be the cause in 13.7% of PFAS patients (14). Further, another study conducted in Japan reported pineapple to be the cause of OAS in 31% of individuals with self-reported OAS symptoms (228 out of 734) (15).
Furthermore, a study conducted in Australia among 163 pediatric atopic patients reported OAS in 24 children, of which 13 reported PFAS. The causative agent identified in the 8 PFAS children by SPT with fresh fruit found pineapple to be a responsible agent in one child (16). Additionally, the SchoolNuts study (a population-based cross-sectional study) conducted in Australia and evaluating self-reported food allergy among 372 children (10-14 years) reported IgE-mediated (likely) pineapple allergy in 4 of them (17).
Pineapple has been found to be associated with unpleasant reactions such as irritation of oral mucosa, which is majorly due to its acidic content or bromelain-mediated proteolysis of oral mucosa. These irritational reactions are usually associated with the enzyme activity of bromelain and are not attributed to the IgE-mediated allergic reactions. However, such symptoms usually appear similar to OAS and becomes difficult to distinguish as they may also produce a false-positive SPT result (6).
Pineapple is native to South America (Brazil and Paraguay), but has presently been cultivated largely in the tropical areas as well as in Europe. The cultivation is predominated in tropical and subtropical regions of the globe and covers more than 82 countries (4). It has been documented that Costa Rica (11%), Philippines (10%), Brazil (8%), Thailand (8%) and India (7%) are the world’s top five pineapple producing countries. It is also produced in subtropical countries, such as Indonesia, China, Malaysia and Kenya (18). Besides, other countries where it is cultivated, include Nigeria, Puerto Rico, Mexico, Hawaii, South Africa, Formosa, Australia and Cuba (4).
Oral ingestion of pineapple (in any form) may induce IgE-mediated allergic reactions, such as OAS or even severe reactions like anaphylaxis (6).
Occupational exposure to bromelain via inhalation (pineapple allergen) may lead to primary sensitization, which could further precipitate systemic allergic reactions on ingestion of pineapple (6, 19).
Pineapple allergy may be associated with pollen allergy (OAS or PFAS) due to presence of profilin pan-allergen, such as Ana c 1. However, presence of bromelain (Ana c 2), may lead to systemic IgE-mediated allergic reactions and, as mentioned, even anaphylaxis as a result of ingestion of pineapple (6, 7).
In a study evaluating 380 patients with PFAS, 18 patients reported with OAS due to ingestion of pineapple, while only one patient reported with systemic allergic reactions (12). In a questionnaire-based study conducted in Korea, PFAS due to pineapple was reported in 13.7% of patients (n=270), with majority of them displaying oropharyngeal symptoms, followed by cutaneous, respiratory or gastrointestinal manifestations (14). Further, in a study conducted in Mexico involving OAS patients, pineapple was found to be the major cause of allergic reactions, which include oropharyngeal symptoms and angioedema, besides nasal and systemic reactions observed in some (9).
Interestingly, a study reported 32 patients who presented with systemic allergic reactions after consumption of pineapple. The major symptoms observed were itchiness, facial edema and rashes, along with gastrointestinal symptoms, such as diarrhea, vomiting and abdominal pain. In addition to this, 20 individuals reported anaphylactoid reactions with reduced heart rate and blood pressure (20). Furthermore, a review of 141 articles reporting 358 cases of anaphylaxis in China during the period from 1980 to 2007 found pineapple to be the most frequent cause, amounting to 25% (90 out of 358) of cases, including one death as a result of anaphylaxis (21).
In an Indian study conducted among 575 patients with asthma and/or allergic rhinitis, history of food allergy was reported in 120 individuals. The SPT performed among food-allergic patients reported 1.6% as having positive SPT towards pineapple (22).
Besides, occupational inhalation of bromelain (major allergen of pineapple), has led to a few cases of asthma as reported in the literature (19, 23, 24).
In a questionnaire-based study conducted among 112 children with atopic dermatitis, pineapple was reported to be the cause of allergic reactions in 30% of these children (25).
Besides the above-mentioned allergic disorders, oral ingestion of pineapple may lead to irritational reactions, mainly restricted to mouth or oral mucosa. Such oral symptoms (irritation on the tongue or oral mucosa, oropharyngeal pain) usually differ from that of OAS, which may also cause pruritis. These irritational symptoms may mainly be attributed to the acidic and bromelain content present in pineapple (6).
Pineapple allergy can be managed by mainly avoiding the consumption of pineapple. However, consuming it after heating may reduce the allergenicity, due to the destruction of its major allergen, bromelain (6). Also, treating the pineapple with salt or consuming it with dairy products may help in reducing the allergenic symptoms caused by it (6, 21).
As of February 22, 2021, only 2 allergenic molecules have been identified, characterized and published officially by World Health Organization (WHO) and International Union of Immunological Studies (IUIS) Allergen Nomenclature Sub-Committee for pineapple (26). The table below provides detailed information on each of the allergenic proteins identified by WHO/IUIS:
|Allergens||Molecular Weight (kDa)||Biochemical name||Allergenicity|
|Ana c 1||15||Profilin||
|Ana c 2||22.8||Bromelain||
kDa: kilodaltons IgE: Immunoglobulin; RAST: Radioallergosorbent test
Bromelain could be used as a marker for determining cross-reactive carbohydrate determinants (CCD). It may help in strengthening the diagnostic techniques, by differentiating the cross-reactivity occurring due to CCD, that are considered as clinically irrelevant and may present with false-positive results (29).
Pollen food allergy syndrome has been reported widely as a result of cross-reactivity between pollen and food allergens. Further, one of the pan-allergen majorly responsible for this cross-reactivity includes profilins. This protein, found in different pollens and plant foods, has shown high-sequence homology among them, leading to cross-reactivity (30). It has been demonstrated in a study where 19 patients of the 380 pollen-allergic patients showed immediate allergic reactions to pineapple (12). Moreover, it has been documented that pineapple profilin, Ana c 1, shares a sequence identity of 80% with natural rubber latex (Hev b 8), 79% with both apple profilin (Mal d 4) as well as sweet cherry (Pru av 4), 78% with peanut (Ara h 5), 77% with both pear (Pyr c 4) and timothy grass pollen (Phl p 12), 72% with celery (Api g 4), and 71% with birch pollen (Bet v 2). Also, cross-reactivity of pineapple has also been reported with kiwi (31) and lychee (Lit c 1) (32).
Latex-fruit syndrome is a term given to the cross-reactive allergic reactions between latex proteins and allergens of several fruits, such as banana, avocado, kiwi, and also pineapple to some extent (12). The cross-reactivity among latex and pineapple was reported in a study conducted in Belgium among 42 rubber-latex allergic patients, of whom 33% reported spontaneous allergic reactions due to consumption of pineapple. Further, determination of specific IgE (sIgE) found 43% of the patients to be positive for pineapple (33).
Pineapple has also been found to be associated with Ficus-fruit syndrome (part of latex-fruit syndrome), due to some degree of cross-reactivity with fig latex (Ficus benjamina). It is said to be associated due to the presence of cysteine proteases like bromelain. This cross-reactivity was found to be independent from the rubber latex (34, 35). Another study conducted among latex-allergic and latex-sensitized, but pollen-allergic patients, found that both profilins as well as bromelain may be responsible for the false positive latex-sIgE in pollen-allergic individuals. This indicates high latex sensitization in pollen-allergic patients which are clinically irrelevant (36).
Furthermore, bromelain is said to be highly homologous to other cysteine proteinases, such as papain. These proteolytic enzymes have been found to be cross-reactive, since papain-sensitized patients may show rapid allergic reactions, like asthma to bromelain (27).
Author: Turacoz Healthcare Solutions
Reviewer: Dr. Fabio Iachetti
Last reviewed: March 2021