Date
22 June 2018
The quality of oysters is easily affected by pollution because they can quickly absorb and accumulate bacteria, viruses and heavy metals. Photo: Wikihow
The quality of oysters is easily affected by pollution because they can quickly absorb and accumulate bacteria, viruses and heavy metals. Photo: Wikihow

Enjoy your oysters without fear

Oysters have always been a favorite among gourmets and buffet-goers. Not only are they delicious, oysters are also very nutritious. They are low in fat, high in protein and loaded with minerals such as selenium, zinc, iron, magnesium and vitamin B.

But some diners report stomach ache, enteritis and diarrhea after eating the delectable seafood. Such cases of food poisoning are believed to be related to the worms found in oysters.

Marine worms live on the outer surface of oyster shells for protection and are often found living inside the crevices of oyster shells. Although marine worms are certainly not appetizing, they indicate how freshly harvested the oysters are from the sea.

Such worms pose no harm to the oysters and they do not live inside oysters. To get rid of them, simply remove the oyster shell and soak the oyster in salty water. Drizzle some lemon juice on top of it and serve.

Oysters are bivalves, and most of them are filter feeders. They scrape detritus from the seabed and capture phytoplankton from the water.

That said, the salty and muddy taste of oysters varies according to their location and the season they are harvested. The species, shape and color of oysters depend on their farming environment and ways of growing.

The quality of oysters is easily affected by pollution because they can quickly absorb and accumulate bacteria, viruses and heavy metals. Bivalves collected from contaminated areas can be purified in clean water, yet the purification cannot remove pathogens, such as norovirus, hepatitis A virus, heavy metals, pesticides, marine toxins and marine bacteria.

Marine bacteria like vibrio vulnificus and vibrio parahaemolyticus are most prevalent during warm seasons and can cause stomach ache, diarrhea and vomiting.

Although current research finds no health hazards from marine worms, they still pose the risk of infection.

Oyster lovers are advised to visit licensed oyster bars and avoid buying cheap oysters harvested from unknown sources, as certificates of origin and proper purification procedures both add to the cost.

To play safe, children, the elderly, pregnant women, and patients with sensitive intestines or low immunity should always consume oysters which have been thoroughly cooked rather than having them raw.

This article appeared in the Hong Kong Economic Journal on Feb 13

Translation by John Chui

[Chinese version 中文版]

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JC/CG

registered dietitian

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