Is eating mussels always safe?

The traditional recommendation that mussels should only be eaten in months with the letter “R” has a traditional background. In our latitudes, mussels are in season from September to April and are mainly offered from German and Dutch harvests. Mussel poisoning only occurs during hot months (without the letter “R”), as  algae  bloom during these months and produce toxins during bloom.

Toxin in Algae

Mussels absorb the algal toxins with the water through filtration processes. The toxins can thus accumulate in dangerous concentrations in the mussels. This process is called “shellfish poisoning” and is reflected in popular wisdom. Furthermore, the storage and transport conditions used to be worse, which tended to lead to spoilage. So it was only logical not to eat mussels during the hotter months.

Year-round control

Today, comprehensive EU legislation ensures that the breeding areas on the coast for algae and bacteria, as well as all coastal areas relevant to the harvesting of mussels, are monitored all year round using an early warning system for algae toxins.

In the cleaning and packaging centers, the mussels are only released for consumption after they have been checked for harmlessness. This largely rules out any adverse health effects on consumers caused by algae toxins and harmful bacteria.

background information

The “R” rule used to make sense because algal bloom toxins, which often lead to mussel poisoning, were a major problem. This natural phenomenon only occurs in the summer months, as there is no algal bloom and the associated formation of toxins in winter.

Through their filtering activity – a mussel filters up to 2 liters of water per hour – mussels absorb the highly toxic algae toxins of the armored whipweed with the water. This can result in dangerous concentrations of poison in the mussel, making it unfit for consumption.

Today, the risk of mussel poisoning from algal toxins or bacterial spoilage in the warm season is very low. Harvested mussels are stored in special seawater sections on the coast called wet storehouses until they are transported. A natural cleaning takes place here, as the mussels excrete sand and other impurities. In addition, modern distribution processes enable a closed cold chain. However, mussels are a perishable  foodstuff  and consumers should take a few things into account when purchasing and preparing them at home.

Tips for Consumers

• If necessary, avoid consumption in summer (June, July, August), as the mussels are spawning during this time and their  taste  may be affected.
• Store freshly bought mussels in a cool place and eat them the next day at the latest.
• Only use closed mussels for the preparation and only eat the open mussels after cooking.