Food Safety
When people experience stomach-flu-like symptoms after eating oysters, the oysters are often blamed first. That reaction is understandable — but not always justified.
Hi Sander,
Thanks for reporting this. We always appreciate receiving complaints about oysters as soon as possible. We have not received any other reports, which makes it unlikely that the oysters were the cause. It may also have been a stomach virus or something else entirely. Please thank the guests for letting us know and wish them a speedy recovery.
Nausea and abdominal pain can have many different causes. Sometimes they occur because something truly was wrong with the food — but sometimes because you believe something was wrong with it. Food poisoning and food contamination are serious risks, and our bodies are evolutionarily primed to respond to them.
An unusual smell, an unexpected taste — or even just the idea that something might be wrong — can trigger a powerful feeling of disgust. This response serves as protection: stopping consumption reduces potential danger. And if one person at the table expresses distrust of the food, others may suddenly start to feel nauseous as well. This is how our brains work, shaped by millions of years of evolution.
When disgust becomes intense, a kind of emergency response is activated. The body stops absorbing nutrients, fluids are no longer reclaimed, and the contents of the digestive system are rapidly expelled — through mouth and bowels. This can happen even when nothing is actually wrong with the food. In such cases, the reaction is usually brief and resolves quickly.
Stomach complaints can also be caused by a virus. The well-known norovirus is highly contagious and causes what is commonly referred to as “stomach flu”: inflammation of the gastrointestinal tract. Each year, around 4.5 million people in the Netherlands experience stomach flu, about 500,000 cases of which are caused by norovirus. You can contract it anywhere someone infected has been — even in places where you did not eat anything.
The chance that norovirus is transmitted through shellfish is very small. The virus does not naturally occur in seawater. Only during large outbreaks can shellfish harvested near sewage discharge points become contaminated via wastewater. For this reason, professional fishers are strictly prohibited from harvesting shellfish near outflows.
With shellfish, there are other natural factors to consider. Certain algae naturally present in the sea can produce biotoxins (such as specific dinoflagellates). Additionally, a background level of E. coli is always present in nature. That is why the Wadden Sea is continuously monitored by inspection vessels from the Ministry. On top of this, our oysters are regularly tested for E. coli and salmonella, which is a legal requirement and supervised by the Netherlands Food and Consumer Product Safety Authority (NVWA).
Another possible cause of symptoms is a protein allergy. Such allergic reactions can arise suddenly and be very severe — sometimes referred to as a protein shock. Unfortunately, this often means a long-term allergy to that specific protein. Fortunately, these proteins are usually species-specific: someone allergic to mussels can often still eat cockles or oysters, and vice versa. The risk of a severe reaction increases when large quantities of a single protein-rich food are consumed at once. In other words: moderation is wise — even when they are delicious.
Reporting illness
We always take reports of illness after eating oysters seriously. If we receive more than one report, all warning signals immediately turn red: we inform other customers and contact the mussel office, which also oversees oysters. In the case of a single report, the cause can be anything — and the likelihood that it originated with us is very small.