f61 Sardine

Sardines (Sardina pilchardus, Sardinops sagax and related species) are members of the herring family found in the Atlantic, Pacific and Mediterranean seas. Fish is an ingested, contact and inhalant allergen; parvalbumin proteins in muscle tissue are the most common allergenic component. Fish allergy is seen more frequently in children than adults and is often severe, producing a range of cutaneous, gastrointestinal, cardiovascular and respiratory symptoms as well as anaphylaxis. Cross-reactivity occurs between bony fish species, although this is not always clinically significant.

Worldwide distribution 

In a Dutch study, only 59% of 38 fish-allergic patients reported a reaction to all fish species ever tried, with the rest tolerating one or more species. Fifteen patients had tried sardine and of these, nine (60%) showed allergic symptoms (5). Sardine was the most common fish causing adverse reactions in a survey of 1,008 Moroccan hospital patients (6).

Pediatric issues 

In a Portuguese study of 81 fish-allergic patients, 95% developed symptoms before the age of 18 years (mean age 24.2 months) and sardine was among the five most common species associated with allergic reactions (7).

In a Moroccan survey of 2,802 high school children, 266 (9.5%) reported fish/shellfish allergy. Of these the most prevalent fish species was sardine, reported by 74.1% of fish-allergic children. The most frequently reported symptoms were cutaneous, followed by gastrointestinal and respiratory symptoms. Children who had been breast-fed in infancy were significantly less likely to be allergic to sardine than those who were not breast-fed (8).

Worldwide distribution 

Sardines are economically important in France, Spain, Portugal and Morocco, where they are processed into fish oil (1, 9). Sardina pilchardus is the most widely consumed fish species in Morocco (6).

Other topics

Fish is consumed as a cooked, fried, pickled, or raw product. Food processing does not seem to affect the allergenic potency of the fish, which is mainly determined by species. Canned sardines may in fact be herrings; the herring family can contain 100 times more allergenic parvalbumins than mackerel or tuna (1, 4, 9).

Main

The main route of exposure is ingestion of fish meat.

Secondary 

Fish can also be a contact and inhalant allergen (10). Occupational asthma has been linked to inhalation of aerosolized, blood-derived allergens during processing of fish (4). 

Parvalbumins from fish are major food allergens causing IgE responses in most fish-allergic individuals (4). In most cases, symptoms are reported after the first contact with fish (7). Reactions range from mild local instances, to severe, acute respiratory or cardiovascular symptoms, and include rhinoconjunctivitis, oral allergy syndrome, angioedema, urticaria, emesis, diarrhea, hoarseness, dyspnea, stridor, tachycardia and anaphylaxis (5, 7).

As well as ingestion, patients may be sensitized to fish via direct skin contact or by inhalation of fish steam during cooking or processing (4, 7). In a Greek study examining changes in fish tolerance with age, 26 of 45 fish-allergic children (58%) reacted after skin contact with fish and 18 (40%) reacted after inhalation of fish. Skin prick tests to sardine showing wheals greater than 6.5 mm were a positive predictive marker for fish allergy in 92% of the study cohort (11).

Prevention strategies 

Contrary to other sources (4), a Moroccan study demonstrated that certain types of processing (fermentation, marinading or canning) reduced sardine immunoreactivity significantly compared to raw fish extract, as measured by differential IgE binding (8). In a similar study, heating and pepsin digestion were also found to reduce immunoreactivity to sardine parvalbumin (6).

Author: RubyDuke Communications

Reviewer: Dr. Christian  Fischer 

Last reviewed:April 2022