Dangers of eating anchovies

During a recent short break to Spain with a couple of friends, one of the culinary delights we enjoyed was anchovies prepared in the Cantabrian style. Wrapped around a green olive, we washed down the plump, pickled fillets with a glass of cardioprotective red wine, and congratulated ourselves on the choice of a healthy tapa.

The anchovy, being an oily fish, is rich in omega-3 fatty acids, well known for its ability to lower levels of triglycerides and cholesterol in the blood. It is also an excellent source of protein, with a fish of average size providing around 9g of protein and only 55 calories.

It is a good source of calcium and particularly of the trace mineral selenium, a powerful antioxidant that is naturally scarce in many parts of the world.

In recent years, concerns over the concentration of mercury in fish meat has led to recommendations limiting the number of portions of fish eaten. However, because the anchovy is a small fish with a short life span, it is unlikely to accumulate significant levels of this element.

Unfortunately, researchers in Spain have recently highlighted the risk of contracting a condition known as anisakiasis, more usually associated with eating sushi, through the ingestion of anchovies infected with parasites of the Anisakis genus and the similar Hysterothylacium aduncum.

The parasites have complex life cycles that begin and end with cetaceans, such as porpoises, and also involve crustaceans, squid and fish. The likelihood of infection depends on the area in which the fish are caught, with a direct correlation between incidence of cetaceans and levels of parasites in infected anchovies.

The parasites are killed by cooking or freezing, and although restaurants are required by European law to freeze to –20C, fillets are not always frozen before pickling. The parasites migrate to the muscles of the fish. This increases the likelihood of infection from pickled anchovies because the larvae have been shown to be present in greater numbers in longer fish, which are preferred for treating with vinegar.

For the parasites, humans are a dead-end host in which the larvae cannot survive and eventually die. The only indication for treatment is small bowel obstruction caused by larval accumulation, which can require emergency surgery.

Last updated
Citation
The Pharmaceutical Journal, December 2009;Online:DOI:10.1211/PJ.2021.1.69388