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Jan 4, 2021 | Nutrition

Seaweed and Heavy Metal

Does seaweed contain heavy metals?

In short, yes, just like some land based foods. Heavy metal occurs naturally in the environment. Marine algae could absorb minerals from the water which makes it high in nutrients. So, it makes perfect sense that seaweed also have the ability to accumulate heavy metals from the ocean.

How much and are we at risk from heavy metal intoxication from eating seaweed?

The amount of accumulation depends on the growing environment and the seaweed species. The toxicity of the elements is affected by the consumed form, amount, and exposure time. Inorganic arsenic is the main concerning heavy metal that is found in seaweed. However, Food Standards Australia and New Zealand sampled and tested most seaweed containing product available in Australia and concluded that except for hijiki seaweed, most seaweed containing products had inorganic arsenic levels below Australia’s maximum concentration allowance in food. When seaweed is eaten as a food in regular consumption, the amount of toxic heavy metal in seaweeds are not high enough to pose serious health risks related to heavy metals.

Where does Alg Seaweed source our seaweed from?

Alg Seaweed source seaweeds from Tasmania and Europe. All seaweed had their nutrient content and heavy metal levels checked from time to time as health and safety are always our priority.

Our wakame seaweed is wild harvested from Tasmania in winter every year. Knowing wakame is a fast-growing seaweed, the chance of accumulating large amount of heavy metal remains low. Also, Tasmania has the reputation of clean water with low contaminant, allowing high quality produce.

Besides wild harvesting Tasmanian wakame, Alg Seaweed is importing the best certified organic seaweed available from Europe. We choose to use farmed seaweeds from a close ecology in order to ensure the traceability of the species. The consistency of the nutritional value is secured by farming the sea vegetables under similar water conditions and harvesting them during the same season every year. By doing so, unpredictable influences of external factors such as water temperature, pH level, heavy metal exposure are minimized, and our seaweed quality could be well controlled.

The amount of inorganic arsenic, mercury, lead, and cadmium in our seaweed range are well below the maximum concentration allowance in food. In general, you should be aware not to eat too much Hijiki at once, while the seaweed has a tendency to accumulate higher levels of the elements, indicating higher risks of heavy metal exposure during consumption. If you feel concerned about exposure to the heavy metals, please consult a health professional to ensure a safe diet. Otherwise, shop now and enjoy our qualified and health boosting seaweed!

To learn more about the different seaweeds we used in the products, read our blog about our trademarked Rainbow Seaweed.


Chen, Q., Pan, X. D., Huang, B. F., & Han, J. L. (2018). Distribution of metals and metalloids in dried seaweeds and health risk to population in southeastern China. Scientific reports8(1), 1-7.

Food Standards Australia and New Zealand, 2016. Food Standard Code – Standard 1.4.1. Food Standards Australia and New Zealand.

Hwang, Y. O., Park, S. G., Park, G. Y., Choi, S. M., & Kim, M. Y. (2010). Total arsenic, mercury, lead, and cadmium contents in edible dried seaweed in Korea. Food Additives and Contaminants: Part B3(1), 7-13.

Smith, J. L., Summers, G., & Wong, R. (2010). Nutrient and heavy metal content of edible seaweeds in New Zealand. New Zealand Journal of Crop and Horticultural Science38(1), 19-28.

Tamele, I. J., & Loureiro, P. V. (2020). Lead, Mercury and Cadmium in Fish and Shellfish from the Indian Ocean and Red Sea (African Countries): Public Health Challenges. Journal of Marine Science and Engineering8(5), 344.

Written by: Sarah Leung