Allison Turner
Nori leaves are indispensable for sushi fans: the dark seaweed gives the small maki sushi their shape. However, according to the Federal Office for Consumer Protection and Food Safety (BVL), the algae leaves are often contaminated with pollutants.
Seaweed leaves are very popular in Asian cuisine. In Germany, too, more and more seaweed is being consumed, especially in sushi. The red algae nori is usually used for sushi. The Federal Office for Consumer Protection and Food Safety (BVL) has now announced that algae leaves are often contaminated with pollutants.
Nori sheets: harmful substances detected
The background: In 2018, the food control authorities of the federal states examined dried algae leaves in a nationwide monitoring program. It was the second investigation of this kind, the first having taken place five years earlier.
The laboratories tested 165 samples of dried seaweed for various chemical elements. The new results have now been published. Cadmium, lead, arsenic and aluminum in particular were found in high concentrations. According to the BVL, the elements are considered potentially harmful to health. The iodine content was also often too high.
These metals were stuck in algae leaves
Cadmium: In the case of the heavy metal cadmium, every tenth algae sample examined exceeded the legal maximum value of 3.0 milligrams of cadmium per kilogram of dried algae that may be used in food supplements.
Lead: The laboratories showed a high lead content. Around every tenth sample contained up to 10 milligrams of lead per kilogram of seaweed. However, a legally permissible maximum value does not yet exist.
Arsenic: The average arsenic content in the algae samples was around 25 milligrams per kilogram. These are high values, but almost exclusively organically bound arsenic could be detected. The health risks associated with this have not yet been conclusively clarified.
The inorganic arsenic compounds, which are problematic according to the Federal Institute for Risk Assessment (BfR), were also detected in almost every second sample. However, the values of 0.1 milligrams per kilogram of algae were very low.
Aluminum: At around 100 milligrams per kilo, the average aluminum content of the algae examined was very high. However, one milligram of aluminum per kilogram of body weight per week is considered safe consumption, according to the BfR. So if you don’t eat several servings of sushi or seaweed every day, you don’t have an increased health risk.
The uranium concentrations found in the samples are similar: The uranium in the algae covers only 0.19 percent of the daily tolerable intake and is therefore usually harmless to health.
Iodine content in algae leaves also very high
In addition to the potentially harmful metals, the algae examined also contained the trace elements iodine, zinc, selenium, manganese and copper.
According to the BVL, no health risk can be assumed for the amounts of zinc, copper, selenium and manganese found. A low intake of trace elements is even necessary for the human organism.
With iodine, however, the laboratory results were different: in over 75 percent of the algae samples, an iodine content of over 20 milligrams per kilogram of algae was measured. Important to know: The BfR only recommends a maximum amount of 0.5 milligrams of iodine per day. A permanent excess of iodine can lead to a malfunction of the thyroid gland.
According to the BfR, if iodine products with an iodine content of more than 20 milligrams per kilo are ingested, this indicates a dangerous excess. Warnings must therefore appear on products with this or a higher iodine content. However, these warnings and consumer information were missing in eight percent of the algae samples.
Our tip: It is best to only buy algae products that clearly state the iodine content and the maximum consumption quantity. Basically, you should not eat seaweed too often.
