How safe is seaweed?
How safe is seaweed? And what are the known risks associated with its consumption?
16 February, 2023
By Bert Popping
Seaweed is the largest aquaculture product in the world. It is a diverse group of multicellular photosynthesising algae found in salt and brackish waters, divided into three groups: red (Rhodophyta), green (Chlorophyta) and brown (Phaeophyta) algae. Green algae are the only ones classified in the phylum Plantae with terrestrial plants, while all three types of macroalgae are commonly referred to as plants. One type of seaweed, known as kelp, is a large brown algae and belongs to the order Laminariales. The chemical composition of seaweed is different from other seafood and terrestrial plants due to high levels of specific polysaccharides. Both nutrients and contaminants are directly taken up through the blades.
As these products have experienced a significant uptake recently and are also being used in several new meat-alternative products, a common risk assessment is needed. While EFSA intends to do this, the Nordic countries did not want to wait that long and called for a common, harmonised risk assessment and legislation – based on their findings.
This risk assessment has now been published in their report which was released earlier this year (2023).
At present, the main chemical hazards that have been identified are iodine, cadmium, and inorganic arsenic and mercury. On the biological side, hazards include Bacillus spp, kainic acid, and proteins potentially triggering allergies.
The levels of heavy metals and iodine vary greatly between and within species and can be affected by various factors, including age, growing conditions, and processing methods.
The report also states that there is still a shortage of data on food hazards in seaweed and more data is needed for proper risk assessments – so maybe expect to see a call for proposals in the next round of Horizon Europe.
The researchers stressed that harmonised legislation would be key to mitigating the risks from consuming seafood in increasing amounts as it is forecasted for the near future.