Macroalgae (or "seaweed")

We broadly categorize macroalgae into three groups: brown algae (Phaeophyceae), which includes kelp and seaweed; green algae (Chlorophyceae); and red algae (Rhodophyceae).

There's a growing interest in the aquaculture and wild harvesting of macroalgae for use in food and feed. This is a relatively new industry, and we're working to gather knowledge on the macroalgae's content of both beneficial nutrients and undesirable substances.

We monitor macroalgae from both aquaculture and wild harvesting. Important risk substances in Norwegian seaweed and kelp include the heavy metal cadmium, inorganic arsenic, and iodine. The latter is a substance we need, but we should not have too much of it.

The Institute of Marine Research (often abbreviated as HI in Norwegian) reports its findings to the Norwegian Food Safety Authority and the European Food Safety Authority (EFSA).

In the latest study, the researchers found significant differences among the various macroalgae species. Brown algae have high levels of iodine, and oarweed contains large amounts of inorganic arsenic. These findings have led the Norwegian Food Safety Authority to now advice against consuming oarweed.