Oral allergy syndrome
Encyclopedia
Oral allergy syndrome or OAS is a type of food allergy
classified by a cluster of allergic reactions in the mouth in response to eating certain (usually fresh) fruits, nuts
, and vegetables that typically develops in adult hay fever
sufferers.
OAS is perhaps the most common food-related allergy in adults. OAS is not a separate food allergy, but rather represents cross-reactivity between distant remnants of tree or weed pollen still found in certain fruits and vegetables. Therefore, OAS is typically only seen in tree and weed allergic patients, and is usually limited to ingestion of only uncooked fruits or vegetables.
Another term used for this syndrome is '"Pollen-Food Allergy."' In adults up to 60% of all food allergic reactions are due to cross-reactions
between foods and inhalative allergens.
However, unlike other food allergies, in oral allergy syndrome, the reaction is limited to the mouth, lips, tongue and throat.
OAS is a Type 1 or IgE
-mediated immune response, which is sometimes called a "true allergy
". The body's immune system produces IgE antibodies against pollen
; in OAS, these antibodies also bind to (or cross-react with) other structurally similar proteins found in botanically related plants.
OAS can occur anytime of the year but is most prevalent during the pollen season. Individuals with OAS usually develop symptoms within a few minutes after eating the food.
. Sometimes other reactions can be triggered in the eyes, nose, and skin. Swelling of the lips, tongue, and uvula
and a sensation of tightness in the throat may be observed. Seldom it can result in anaphylaxis
. If a sufferer swallows the food, and the allergen is not destroyed by the stomach acids there is a good chance that there will be a reaction from histamine release later in the gastrointestinal tract
. Vomiting
, diarrhea
, severe indigestion, or cramps
may occur. Rarely, OAS may be severe and present as wheezing, vomiting, hives and low blood pressure
.
releases from mast cells located in the oropharynx, gut and skin when IgE binds to the molecule causing local inflammation
.
The triggering molecule involved is known as an allergen. Allergens vary in their stability and may or may not survive digestion, storage, heat, cold, cooking or pasteurisation.
Lipid transfer proteins
(LTP) are not easily denatured by digestion or cooking and are important triggers of anaphylaxis.
The antibody may react to the linear (amino acid) sequence of the protein
or to a conformational
epitope. If the response is to the conformational epitope, then the person with OAS may be able to eat the food when it is cooked, but not when it is raw. If the response is to the linear sequence (common in tree pollen/nut allergies), then cooking the food has no effect on its ability to trigger an allergic reaction.
Individuals with an allergy to tree pollen may develop OAS to a variety of foods. While the tree pollen allergy has been worked out, the grass pollen is not well understood. Furthermore, some individuals have severe reactions to certain fruits and vegetables that do not fall into any particular allergy category. In recent years, it has also become apparent that when tropical foods initiate OAS, allergy to latex
may be the underlying cause.
Because the allergenic proteins associated with OAS are usually destroyed by cooking, most reactions are caused by eating raw foods. The main exceptions to this are celery and nuts, which may cause reactions even after being cooked.
is associated with OAS reactions to banana
, watermelon
, cantaloupe
, honeydew
, zucchini
, and cucumber
. This does not mean that all sufferers of an allergy to ragweed will experience adverse effects from all or even any of these foods. Reactions may begin with one type of food and with reactions to others developing later. However, reaction to one or more foods in any given category does not necessarily mean a person is allergic to all foods in that group.
and an atopic family history. Eczema, otolaryngeal symptoms of hay fever or asthma will often dominate leading to the food allergy being unsuspected. Often well-cooked, canned, pasteurized or frozen food offenders cause little to no reaction due to denaturation
of the cross-reacting proteins, causing delay and confusion in diagnosis as the symptoms are elicited only to the raw or fully ripened fresh foods. Correct diagnosis of the allergen type/s involved is critical. OAS sufferers may be allergic to more than just pollen. Oral reactions to food are often mistakenly self-diagnosed by patients as caused by pesticides or other contaminants. Other reactions to food—such as lactose intolerance
and intolerances which result from a patient being unable to metabolize naturally occurring chemicals (e.g., salicylates and proteins) in food—need to be distinguished from the systemic symptoms of OAS.
The cornerstone of diagnosis remains an accurate history of symptoms and an elimination diet
followed by a food challenge. Skin prick testing and RAST testing are used as adjuncts to the clinical history—they cannot be used for diagnosis alone. Prick to prick testing with fresh foods is more reliable for some extremely labile allergens such as those found in apple than testing with commercial extracts which will commonly give a false negative. If the history is suggestive and the skin prick test negative, fresh foods should be used.
, tingling
or pain develops while eating certain foods, then it is wise to see an allergy specialist. Before a diagnosis can be made, keep a food diary. This is important as the physician
can then perform an allergy test. Before testing is started, a comprehensive history is obtained so that random testing is avoided and saves money. The diagnosis of OAS may involve skin prick tests, blood tests, patch tests or oral challenges. When OAS is suspected, the oral challenge test is ideal.
In addition, patients are advised to avoid the triggering foods, particularly nuts.
Peeling or cooking the foods has been shown to eliminate the effects of some allergens such as mal d 1 (apple), but not others such as celery or strawberry. In the case of foods such as hazelnut, which have more than one allergen, cooking may eliminate one allergen but not the other.
Antihistamines may also relieve the symptoms of the allergy by blocking the immune pathway. Persons with a history of severe anaphylactic reaction may carry an injectable emergency dose of epinephrine
(such as an EpiPen). Allergy immunotherapy has been reported to improve or cure OAS in some patients. Immunotherapy with extracts containing birch pollen may benefit OAS sufferers of apple or hazelnut related to birch pollen-allergens. Even so, the increase in the amount of apple/hazelnut tolerated was small (from 12.6 to 32.6 g apple), and as a result, a patient's management of OAS would be limited.
Food allergy
A food allergy is an adverse immune response to a food protein. They are distinct from other adverse responses to food, such as food intolerance, pharmacological reactions, and toxin-mediated reactions....
classified by a cluster of allergic reactions in the mouth in response to eating certain (usually fresh) fruits, nuts
Nut (fruit)
A nut is a hard-shelled fruit of some plants having an indehiscent seed. While a wide variety of dried seeds and fruits are called nuts in English, only a certain number of them are considered by biologists to be true nuts...
, and vegetables that typically develops in adult hay fever
Hay Fever
Hay Fever is a comic play written by Noël Coward in 1924 and first produced in 1925 with Marie Tempest as the first Judith Bliss. Laura Hope Crews played the role in New York...
sufferers.
OAS is perhaps the most common food-related allergy in adults. OAS is not a separate food allergy, but rather represents cross-reactivity between distant remnants of tree or weed pollen still found in certain fruits and vegetables. Therefore, OAS is typically only seen in tree and weed allergic patients, and is usually limited to ingestion of only uncooked fruits or vegetables.
Another term used for this syndrome is '"Pollen-Food Allergy."' In adults up to 60% of all food allergic reactions are due to cross-reactions
Cross-reactivity
Cross-reactivity is the reaction between an antibody and an antigen that differs from the immunogen. It is sometimes also referred to as crossimmunity or cross-protective immunity...
between foods and inhalative allergens.
However, unlike other food allergies, in oral allergy syndrome, the reaction is limited to the mouth, lips, tongue and throat.
OAS is a Type 1 or IgE
Immunoglobulin E
Immunoglobulin E is a class of antibody that has been found only in mammals. IgE is a monomeric antibody with 4 Ig-like domains...
-mediated immune response, which is sometimes called a "true allergy
Allergy
An Allergy is a hypersensitivity disorder of the immune system. Allergic reactions occur when a person's immune system reacts to normally harmless substances in the environment. A substance that causes a reaction is called an allergen. These reactions are acquired, predictable, and rapid...
". The body's immune system produces IgE antibodies against pollen
Pollen
Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...
; in OAS, these antibodies also bind to (or cross-react with) other structurally similar proteins found in botanically related plants.
OAS can occur anytime of the year but is most prevalent during the pollen season. Individuals with OAS usually develop symptoms within a few minutes after eating the food.
Symptoms
OAS sufferers may have any of a number of allergic reactions that usually occur very rapidly, within minutes of eating a trigger food. The most common reaction is an itching or burning sensation in the lips, mouth, ear canal, and/or pharynxPharynx
The human pharynx is the part of the throat situated immediately posterior to the mouth and nasal cavity, and anterior to the esophagus and larynx. The human pharynx is conventionally divided into three sections: the nasopharynx , the oropharynx , and the laryngopharynx...
. Sometimes other reactions can be triggered in the eyes, nose, and skin. Swelling of the lips, tongue, and uvula
Uvula
The palatine uvula, usually referred to as simply the uvula , is the conic projection from the posterior edge of the middle of the soft palate, composed of connective tissue containing a number of racemose glands, and some muscular fibers .-Function in language:The uvula plays a role in the...
and a sensation of tightness in the throat may be observed. Seldom it can result in anaphylaxis
Anaphylaxis
Anaphylaxis is defined as "a serious allergic reaction that is rapid in onset and may cause death". It typically results in a number of symptoms including throat swelling, an itchy rash, and low blood pressure...
. If a sufferer swallows the food, and the allergen is not destroyed by the stomach acids there is a good chance that there will be a reaction from histamine release later in the gastrointestinal tract
Gastrointestinal tract
The human gastrointestinal tract refers to the stomach and intestine, and sometimes to all the structures from the mouth to the anus. ....
. Vomiting
Vomiting
Vomiting is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose...
, diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
, severe indigestion, or cramps
Abdominal pain
Abdominal pain can be one of the symptoms associated with transient disorders or serious disease. Making a definitive diagnosis of the cause of abdominal pain can be difficult, because many diseases can result in this symptom. Abdominal pain is a common problem...
may occur. Rarely, OAS may be severe and present as wheezing, vomiting, hives and low blood pressure
Hypotension
In physiology and medicine, hypotension is abnormally low blood pressure, especially in the arteries of the systemic circulation. It is best understood as a physiologic state, rather than a disease. It is often associated with shock, though not necessarily indicative of it. Hypotension is the...
.
Mechanism
In OAS, the immune system produces antibodies that are capable of binding to both pollen proteins and structurally similar food proteins. Consequently, the same immune system response can trigger allergy symptoms in two different situations: hay fever (in the presence of pollen) and food allergy (in the presence of certain foods). HistamineHistamine
Histamine is an organic nitrogen compound involved in local immune responses as well as regulating physiological function in the gut and acting as a neurotransmitter. Histamine triggers the inflammatory response. As part of an immune response to foreign pathogens, histamine is produced by...
releases from mast cells located in the oropharynx, gut and skin when IgE binds to the molecule causing local inflammation
Inflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
.
The triggering molecule involved is known as an allergen. Allergens vary in their stability and may or may not survive digestion, storage, heat, cold, cooking or pasteurisation.
Lipid transfer proteins
Lipid transfer proteins
Plant lipid transfer proteins, also known as plant LTPs or PLTPs, are a group of highly-conserved proteins of about 9kDa found in higher plant tissues. As its name implies, lipid transfer proteins are responsible for the shuttling of phospholipids and other fatty acid groups between cell membranes...
(LTP) are not easily denatured by digestion or cooking and are important triggers of anaphylaxis.
The antibody may react to the linear (amino acid) sequence of the protein
Primary structure
The primary structure of peptides and proteins refers to the linear sequence of its amino acid structural units. The term "primary structure" was first coined by Linderstrøm-Lang in 1951...
or to a conformational
Tertiary structure
In biochemistry and molecular biology, the tertiary structure of a protein or any other macromolecule is its three-dimensional structure, as defined by the atomic coordinates.-Relationship to primary structure:...
epitope. If the response is to the conformational epitope, then the person with OAS may be able to eat the food when it is cooked, but not when it is raw. If the response is to the linear sequence (common in tree pollen/nut allergies), then cooking the food has no effect on its ability to trigger an allergic reaction.
Causes
OAS produces symptoms when an affected person eats certain fruits, vegetables and nuts. Some individuals may only show allergy to only one particular food, and others may show an allergic response to many foods.Individuals with an allergy to tree pollen may develop OAS to a variety of foods. While the tree pollen allergy has been worked out, the grass pollen is not well understood. Furthermore, some individuals have severe reactions to certain fruits and vegetables that do not fall into any particular allergy category. In recent years, it has also become apparent that when tropical foods initiate OAS, allergy to latex
Latex
Latex is the stable dispersion of polymer microparticles in an aqueous medium. Latexes may be natural or synthetic.Latex as found in nature is a milky fluid found in 10% of all flowering plants . It is a complex emulsion consisting of proteins, alkaloids, starches, sugars, oils, tannins, resins,...
may be the underlying cause.
Because the allergenic proteins associated with OAS are usually destroyed by cooking, most reactions are caused by eating raw foods. The main exceptions to this are celery and nuts, which may cause reactions even after being cooked.
Cross reactions
Allergies to a certain pollen are associated with OAS reactions to certain foods. For instance, an allergy to ragweedRagweed
Ragweeds are flowering plants in the genus Ambrosia in the sunflower family Asteraceae. Common names include bitterweeds and bloodweeds....
is associated with OAS reactions to banana
Banana
Banana is the common name for herbaceous plants of the genus Musa and for the fruit they produce. Bananas come in a variety of sizes and colors when ripe, including yellow, purple, and red....
, watermelon
Watermelon
Watermelon is a vine-like flowering plant originally from southern Africa. Its fruit, which is also called watermelon, is a special kind referred to by botanists as a pepo, a berry which has a thick rind and fleshy center...
, cantaloupe
Cantaloupe
"Rockmelon" redirects here, for the band see Rockmelons. See also Cantaloupe .Cantaloupe refers to a variety of Cucumis melo, a species in the family Cucurbitaceae which includes nearly all melons and squashes. Cantaloupes range in size from...
, honeydew
Honeydew (melon)
Honeydew is a cultivar group of the muskmelon, Cucumis melo Inodorus group, which includes crenshaw, casaba, Persian, winter, and other mixed melons.-Characteristics:...
, zucchini
Zucchini
The zucchini is a summer squash which often grows to nearly a meter in length, but which is usually harvested at half that size or less. It is a hybrid of the cucumber. Along with certain other squashes, it belongs to the species Cucurbita pepo. Zucchini can be dark or light green...
, and cucumber
Cucumber
The cucumber is a widely cultivated plant in the gourd family Cucurbitaceae, which includes squash, and in the same genus as the muskmelon. The plant is a creeping vine which bears cylindrical edible fruit when ripe. There are three main varieties of cucumber: "slicing", "pickling", and...
. This does not mean that all sufferers of an allergy to ragweed will experience adverse effects from all or even any of these foods. Reactions may begin with one type of food and with reactions to others developing later. However, reaction to one or more foods in any given category does not necessarily mean a person is allergic to all foods in that group.
- AlderAlderAlder is the common name of a genus of flowering plants belonging to the birch family . The genus comprises about 30 species of monoecious trees and shrubs, few reaching large size, distributed throughout the North Temperate Zone and in the Americas along the Andes southwards to...
pollen: almondAlmondThe almond , is a species of tree native to the Middle East and South Asia. Almond is also the name of the edible and widely cultivated seed of this tree...
s, appleAppleThe apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family . It is one of the most widely cultivated tree fruits, and the most widely known of the many members of genus Malus that are used by humans. Apple grow on small, deciduous trees that blossom in the spring...
s, celeryCeleryApium graveolens is a plant species in the family Apiaceae commonly known as celery or celeriac , depending on whether the petioles or roots are eaten: celery refers to the former and celeriac to the latter. Apium graveolens grows to 1 m tall...
, cherriesCherryThe cherry is the fruit of many plants of the genus Prunus, and is a fleshy stone fruit. The cherry fruits of commerce are usually obtained from a limited number of species, including especially cultivars of the wild cherry, Prunus avium....
, hazel nuts, peachPeachThe peach tree is a deciduous tree growing to tall and 6 in. in diameter, belonging to the subfamily Prunoideae of the family Rosaceae. It bears an edible juicy fruit called a peach...
es, pearPearThe pear is any of several tree species of genus Pyrus and also the name of the pomaceous fruit of these trees. Several species of pear are valued by humans for their edible fruit, but the fruit of other species is small, hard, and astringent....
s, parsleyParsleyParsley is a species of Petroselinum in the family Apiaceae, native to the central Mediterranean region , naturalized elsewhere in Europe, and widely cultivated as an herb, a spice and a vegetable.- Description :Garden parsley is a bright green hairless biennial herbaceous plant in temperate...
, strawberryStrawberryFragaria is a genus of flowering plants in the rose family, Rosaceae, commonly known as strawberries for their edible fruits. Although it is commonly thought that strawberries get their name from straw being used as a mulch in cultivating the plants, the etymology of the word is uncertain. There...
, raspberryRaspberryThe raspberry or hindberry is the edible fruit of a multitude of plant species in the genus Rubus, most of which are in the subgenus Idaeobatus; the name also applies to these plants themselves... - BirchBirchBirch is a tree or shrub of the genus Betula , in the family Betulaceae, closely related to the beech/oak family, Fagaceae. The Betula genus contains 30–60 known taxa...
pollen: almondAlmondThe almond , is a species of tree native to the Middle East and South Asia. Almond is also the name of the edible and widely cultivated seed of this tree...
s, appleAppleThe apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family . It is one of the most widely cultivated tree fruits, and the most widely known of the many members of genus Malus that are used by humans. Apple grow on small, deciduous trees that blossom in the spring...
s, apricotApricotThe apricot, Prunus armeniaca, is a species of Prunus, classified with the plum in the subgenus Prunus. The native range is somewhat uncertain due to its extensive prehistoric cultivation.- Description :...
s, avocados, bananas, carrots, celeryCeleryApium graveolens is a plant species in the family Apiaceae commonly known as celery or celeriac , depending on whether the petioles or roots are eaten: celery refers to the former and celeriac to the latter. Apium graveolens grows to 1 m tall...
, cherriesCherryThe cherry is the fruit of many plants of the genus Prunus, and is a fleshy stone fruit. The cherry fruits of commerce are usually obtained from a limited number of species, including especially cultivars of the wild cherry, Prunus avium....
, chicoryChicoryCommon chicory, Cichorium intybus, is a somewhat woody, perennial herbaceous plant usually with bright blue flowers, rarely white or pink. Various varieties are cultivated for salad leaves, chicons , or for roots , which are baked, ground, and used as a coffee substitute and additive. It is also...
, corianderCorianderCoriander is an annual herb in the family Apiaceae. Coriander is native to southern Europe and North Africa to southwestern Asia. It is a soft, hairless plant growing to tall. The leaves are variable in shape, broadly lobed at the base of the plant, and slender and feathery higher on the...
, fennelFennelFennel is a plant species in the genus Foeniculum . It is a member of the family Apiaceae . It is a hardy, perennial, umbelliferous herb, with yellow flowers and feathery leaves...
, figFicusFicus is a genus of about 850 species of woody trees, shrubs, vines, epiphytes, and hemiepiphyte in the family Moraceae. Collectively known as fig trees or figs, they are native throughout the tropics with a few species extending into the semi-warm temperate zone. The Common Fig Ficus is a genus of...
, hazel nuts, kiwifruitKiwifruitThe kiwifruit, often shortened to kiwi in many parts of the world, is the edible berry of a cultivar group of the woody vine Actinidia deliciosa and hybrids between this and other species in the genus Actinidia....
, nectarines, parsleyParsleyParsley is a species of Petroselinum in the family Apiaceae, native to the central Mediterranean region , naturalized elsewhere in Europe, and widely cultivated as an herb, a spice and a vegetable.- Description :Garden parsley is a bright green hairless biennial herbaceous plant in temperate...
, parsnips, peachPeachThe peach tree is a deciduous tree growing to tall and 6 in. in diameter, belonging to the subfamily Prunoideae of the family Rosaceae. It bears an edible juicy fruit called a peach...
es, pearPearThe pear is any of several tree species of genus Pyrus and also the name of the pomaceous fruit of these trees. Several species of pear are valued by humans for their edible fruit, but the fruit of other species is small, hard, and astringent....
s, pepperCapsicumCapsicum is a genus of flowering plants in the nightshade family, Solanaceae. Its species are native to the Americas where they have been cultivated for thousands of years, but they are now also cultivated worldwide, used as spices, vegetables, and medicines - and have become are a key element in...
s, plumPlumA plum or gage is a stone fruit tree in the genus Prunus, subgenus Prunus. The subgenus is distinguished from other subgenera in the shoots having a terminal bud and solitary side buds , the flowers in groups of one to five together on short stems, and the fruit having a groove running down one...
s, potatoPotatoThe potato is a starchy, tuberous crop from the perennial Solanum tuberosum of the Solanaceae family . The word potato may refer to the plant itself as well as the edible tuber. In the region of the Andes, there are some other closely related cultivated potato species...
es, prunePruneA prune is any of various plum cultivars, mostly Prunus domestica or European Plum, sold as fresh or dried fruit. The dried fruit is also referred to as a dried plum...
s, soy, strawberries, wheatWheatWheat is a cereal grain, originally from the Levant region of the Near East, but now cultivated worldwide. In 2007 world production of wheat was 607 million tons, making it the third most-produced cereal after maize and rice...
; Potential: walnuts - Grass pollen: figFicusFicus is a genus of about 850 species of woody trees, shrubs, vines, epiphytes, and hemiepiphyte in the family Moraceae. Collectively known as fig trees or figs, they are native throughout the tropics with a few species extending into the semi-warm temperate zone. The Common Fig Ficus is a genus of...
, melons, tomatoes, orangesOrange (fruit)An orange—specifically, the sweet orange—is the citrus Citrus × sinensis and its fruit. It is the most commonly grown tree fruit in the world.... - Mugwort pollen : carrots, celeryCeleryApium graveolens is a plant species in the family Apiaceae commonly known as celery or celeriac , depending on whether the petioles or roots are eaten: celery refers to the former and celeriac to the latter. Apium graveolens grows to 1 m tall...
, corianderCorianderCoriander is an annual herb in the family Apiaceae. Coriander is native to southern Europe and North Africa to southwestern Asia. It is a soft, hairless plant growing to tall. The leaves are variable in shape, broadly lobed at the base of the plant, and slender and feathery higher on the...
, fennelFennelFennel is a plant species in the genus Foeniculum . It is a member of the family Apiaceae . It is a hardy, perennial, umbelliferous herb, with yellow flowers and feathery leaves...
, parsleyParsleyParsley is a species of Petroselinum in the family Apiaceae, native to the central Mediterranean region , naturalized elsewhere in Europe, and widely cultivated as an herb, a spice and a vegetable.- Description :Garden parsley is a bright green hairless biennial herbaceous plant in temperate...
, peppersCapsicumCapsicum is a genus of flowering plants in the nightshade family, Solanaceae. Its species are native to the Americas where they have been cultivated for thousands of years, but they are now also cultivated worldwide, used as spices, vegetables, and medicines - and have become are a key element in...
, sunflowerSunflowerSunflower is an annual plant native to the Americas. It possesses a large inflorescence . The sunflower got its name from its huge, fiery blooms, whose shape and image is often used to depict the sun. The sunflower has a rough, hairy stem, broad, coarsely toothed, rough leaves and circular heads... - RagweedRagweedRagweeds are flowering plants in the genus Ambrosia in the sunflower family Asteraceae. Common names include bitterweeds and bloodweeds....
pollen : bananaBananaBanana is the common name for herbaceous plants of the genus Musa and for the fruit they produce. Bananas come in a variety of sizes and colors when ripe, including yellow, purple, and red....
, cantaloupeCantaloupe"Rockmelon" redirects here, for the band see Rockmelons. See also Cantaloupe .Cantaloupe refers to a variety of Cucumis melo, a species in the family Cucurbitaceae which includes nearly all melons and squashes. Cantaloupes range in size from...
, cucumberCucumberThe cucumber is a widely cultivated plant in the gourd family Cucurbitaceae, which includes squash, and in the same genus as the muskmelon. The plant is a creeping vine which bears cylindrical edible fruit when ripe. There are three main varieties of cucumber: "slicing", "pickling", and...
, green pepper, paprikaPaprikaPaprika is a spice made from the grinding of dried fruits of Capsicum annuum . In many European languages, the word paprika refers to bell peppers themselves. The seasoning is used in many cuisines to add color and flavor to dishes. Paprika can range from mild to hot...
, sunflower seeds/oil, honeydewHoneydew (melon)Honeydew is a cultivar group of the muskmelon, Cucumis melo Inodorus group, which includes crenshaw, casaba, Persian, winter, and other mixed melons.-Characteristics:...
, watermelonWatermelonWatermelon is a vine-like flowering plant originally from southern Africa. Its fruit, which is also called watermelon, is a special kind referred to by botanists as a pepo, a berry which has a thick rind and fleshy center...
, zucchiniZucchiniThe zucchini is a summer squash which often grows to nearly a meter in length, but which is usually harvested at half that size or less. It is a hybrid of the cucumber. Along with certain other squashes, it belongs to the species Cucurbita pepo. Zucchini can be dark or light green...
, echinaceaEchinaceaEchinacea is a genus of herbaceous flowering plants in the daisy family, Asteraceae. The nine species it contains are commonly called purple coneflowers. They are endemic to eastern and central North America, where they are found growing in moist to dry prairies and open wooded areas. They have...
, artichokeArtichoke-Plants:* Globe artichoke, a partially edible perennial thistle originating in southern Europe around the Mediterranean* Jerusalem artichoke, a species of sunflower with an edible tuber...
, dandelions, honey (if bees pollinate from wild flowers), hibiscusHibiscusHibiscus is a genus of flowering plants in the mallow family, Malvaceae. It is quite large, containing several hundred species that are native to warm-temperate, subtropical and tropical regions throughout the world...
or chamomileChamomileChamomile or camomile is a common name for several daisy-like plants of the family Asteraceae. These plants are best known for their ability to be made into an infusion which is commonly used to help with sleep and is often served with either honey or lemon. Because chamomile can cause uterine...
tea - Possible cross-reactions (to any of the above): berries (strawberries, blueberries, raspberriesRaspberryThe raspberry or hindberry is the edible fruit of a multitude of plant species in the genus Rubus, most of which are in the subgenus Idaeobatus; the name also applies to these plants themselves...
, etc), citrusCitrusCitrus is a common term and genus of flowering plants in the rue family, Rutaceae. Citrus is believed to have originated in the part of Southeast Asia bordered by Northeastern India, Myanmar and the Yunnan province of China...
(orangesOrange (fruit)An orange—specifically, the sweet orange—is the citrus Citrus × sinensis and its fruit. It is the most commonly grown tree fruit in the world....
, lemons, etc), grapes, mangoMangoThe mango is a fleshy stone fruit belonging to the genus Mangifera, consisting of numerous tropical fruiting trees in the flowering plant family Anacardiaceae. The mango is native to India from where it spread all over the world. It is also the most cultivated fruit of the tropical world. While...
, figsFIGSFIGS is an acronym for French, Italian, German, Spanish. These are usually the first four languages chosen to localize products into when a company enters the European market....
, peanutPeanutThe peanut, or groundnut , is a species in the legume or "bean" family , so it is not a nut. The peanut was probably first cultivated in the valleys of Peru. It is an annual herbaceous plant growing tall...
, pineapplePineapplePineapple is the common name for a tropical plant and its edible fruit, which is actually a multiple fruit consisting of coalesced berries. It was given the name pineapple due to its resemblance to a pine cone. The pineapple is by far the most economically important plant in the Bromeliaceae...
, pomegranates, watermelonWatermelonWatermelon is a vine-like flowering plant originally from southern Africa. Its fruit, which is also called watermelon, is a special kind referred to by botanists as a pepo, a berry which has a thick rind and fleshy center...
Diagnosis
The patient typically already has a history of atopyAtopy
Atopy or atopic syndrome is a predisposition toward developing certain allergic hypersensitivity reactions.Atopy may have a hereditary component, although contact with the allergen must occur before the hypersensitivity reaction can develop ....
and an atopic family history. Eczema, otolaryngeal symptoms of hay fever or asthma will often dominate leading to the food allergy being unsuspected. Often well-cooked, canned, pasteurized or frozen food offenders cause little to no reaction due to denaturation
Denaturation (biochemistry)
Denaturation is a process in which proteins or nucleic acids lose their tertiary structure and secondary structure by application of some external stress or compound, such as a strong acid or base, a concentrated inorganic salt, an organic solvent , or heat...
of the cross-reacting proteins, causing delay and confusion in diagnosis as the symptoms are elicited only to the raw or fully ripened fresh foods. Correct diagnosis of the allergen type/s involved is critical. OAS sufferers may be allergic to more than just pollen. Oral reactions to food are often mistakenly self-diagnosed by patients as caused by pesticides or other contaminants. Other reactions to food—such as lactose intolerance
Lactose intolerance
Lactose intolerance, also called lactase deficiency or hypolactasia, is the inability to digest and metabolize lactose, a sugar found in milk...
and intolerances which result from a patient being unable to metabolize naturally occurring chemicals (e.g., salicylates and proteins) in food—need to be distinguished from the systemic symptoms of OAS.
The cornerstone of diagnosis remains an accurate history of symptoms and an elimination diet
Elimination diet
An elimination diet is a method of identifying foods that an individual cannot consume without adverse effects. Adverse effects may be due to food allergy, food intolerance, other physiological mechanisms , or a combination of these...
followed by a food challenge. Skin prick testing and RAST testing are used as adjuncts to the clinical history—they cannot be used for diagnosis alone. Prick to prick testing with fresh foods is more reliable for some extremely labile allergens such as those found in apple than testing with commercial extracts which will commonly give a false negative. If the history is suggestive and the skin prick test negative, fresh foods should be used.
Testing
Many people have no idea that they have an OAS syndrome. However, if swellingSwelling (medical)
In medical parlance, swelling is the transient enlargement or protuberance in the body and may include tumors. According to cause, it may be congenital, traumatic, inflammatory, neoplastic or miscellaneous....
, tingling
Paresthesia
Paresthesia , spelled "paraesthesia" in British English, is a sensation of tingling, burning, pricking, or numbness of a person's skin with no apparent long-term physical effect. It is more generally known as the feeling of "pins and needles" or of a limb "falling asleep"...
or pain develops while eating certain foods, then it is wise to see an allergy specialist. Before a diagnosis can be made, keep a food diary. This is important as the physician
Physician
A physician is a health care provider who practices the profession of medicine, which is concerned with promoting, maintaining or restoring human health through the study, diagnosis, and treatment of disease, injury and other physical and mental impairments...
can then perform an allergy test. Before testing is started, a comprehensive history is obtained so that random testing is avoided and saves money. The diagnosis of OAS may involve skin prick tests, blood tests, patch tests or oral challenges. When OAS is suspected, the oral challenge test is ideal.
Exams
To confirm OAS, the suspected food is consumed in a normal way. The period of observation after ingestion and symptoms are recorded. If other co factors like combined foods are required, this is also replicated in the test. For example, if the individual always develops symptoms after eating followed by exercise, then this is replicated in the laboratory.Treatment
OAS must be managed in conjunction with the patient's other allergies, primarily the allergy to pollen. The symptom severity may wax and wane with the pollen levels. Published pollen counts and seasonal charts are useful but may be ineffective in cases of high wind or unusual weather, as pollen can travel hundreds of kilometers from other areas. The syndrome will abate within 2–3 years if the patient moves to an area free of the triggering pollen. Moving usually results in the development of allergy to the local pollens.In addition, patients are advised to avoid the triggering foods, particularly nuts.
Peeling or cooking the foods has been shown to eliminate the effects of some allergens such as mal d 1 (apple), but not others such as celery or strawberry. In the case of foods such as hazelnut, which have more than one allergen, cooking may eliminate one allergen but not the other.
Antihistamines may also relieve the symptoms of the allergy by blocking the immune pathway. Persons with a history of severe anaphylactic reaction may carry an injectable emergency dose of epinephrine
Epinephrine
Epinephrine is a hormone and a neurotransmitter. It increases heart rate, constricts blood vessels, dilates air passages and participates in the fight-or-flight response of the sympathetic nervous system. In chemical terms, adrenaline is one of a group of monoamines called the catecholamines...
(such as an EpiPen). Allergy immunotherapy has been reported to improve or cure OAS in some patients. Immunotherapy with extracts containing birch pollen may benefit OAS sufferers of apple or hazelnut related to birch pollen-allergens. Even so, the increase in the amount of apple/hazelnut tolerated was small (from 12.6 to 32.6 g apple), and as a result, a patient's management of OAS would be limited.