Oyster is a food which may result in allergy symptoms in sensitised individuals.

Oyster Allergy Test: Allergen Exposure

Oyster is the common name for various families of bivalve molluscs living in marine or brackish environments. Certain species have been consumed by humans since prehistoric times, either raw or cooked in a number of ways. They are commonly farmed, a practice which began as early as the time of the Roman Empire. Oysters are now generally regarded as a delicacy, although in the past consumption was much more common.

Oysters are commonly served raw, with a simple dressing such as lemon juice, vinegar or tabasco sauce, but they may also be smoked, boiled, baked, fried, roasted, stewed, canned, pickled, steamed, or broiled. They are also an ingredient in some sauces and beverages.

Oysters Rockefeller is an American dish of oysters topped with butter and parsley sauce, coated in breadcrumbs, then baked in their shells.

The flavour is described as salty, briny, buttery, metallic, or even fruity, and varies considerably based on the age of the oyster, the habitat in which it developed and the time since it was harvested.

Traditionally, oysters have been considered to be an aphrodisiac, which may be in part due to their high zinc content, which is essential for the production of testosterone. They are also an excellent source of iron, calcium, and selenium, as well as vitamin A and vitamin B12.

Oyster Allergy Test: Allergen Description

No specific allergens present in oyster have been characterised, although a number of proteins have been identified.

Oyster Allergy Test: Potential Cross-Reactivity

Oyster and crustacea extracts show common antigenic structures. Some cross reactivity to blue mussel can be expected.

Cross-reactions are found between molluscs, especially within the same class (bivalves, cephalopods or gastropods).

Therefore those allergic to bivalves (clams, mussels, oysters, and scallops) are likely to react to other bivalves, while those reacting to gastropods (abalone, limpets, snails, winkles and whelks) are likely to react to other gastropods.

Oyster Allergy Test: Clinical Experience

Oyster shell dust has been identified as an inhalant allergen in occupational asthma. An early study from Japan identified oyster shell as an inhalant allergen in occupational bronchial asthma in workers at processing plants.

Exercise-induced anaphylaxis has been reported after ingestion of smoked oysters.

Shellfish, including oyster, is one of the more common food allergies, and usually persists throughout the patient’s lifetime. The majority of people (around 60%) of shellfish-allergic people experience their first allergic reaction as adults.

Symptoms can be severe and potentially life-threatening, including anaphylaxis. Even very small amounts of shellfish can provoke a reaction.

Exposure to the steam from cooking shellfish has been reported to cause an allergic reaction in some cases, due to the presence of allergenic proteins in the steam.

Other reactions

Seafood may contain high levels of histamine.

Shellfish poisoning is a potential consequence of ingesting shellfish contaminated with any one of a number of toxins. Symptoms may include nausea, vomiting, abdominal pain and diarrhea; chills, fever or headache; conjunctival irritation, sneezing and rhinorrhea and even paralysis.

Oysters may contain high bacterial loads of human pathogens in the warm months, most notably Vibrio vulnificus and Vibrio parahaemolyticus.