Commercially available kelp and seaweed products – valuable iodine source or risk of excess intake?

  • Inger Aakre Department of Seafood and Nutrition, Institute of Marine Research,Bergen, Norway
  • Dina Doblaug Solli Department of Seafood and Nutrition, Institute of Marine Research, Bergen, and Department of Clinical Science, Faculty of Medicine, University of Bergen, Bergen, Norway
  • Maria Wik Markhus Department of Seafood and Nutrition, Institute of Marine Research,Bergen, Norway
  • Hanne K. Mæhre Nofima, Norwegian Institute of Food, Fisheries and Aquaculture Research, Ås, Norway
  • Lisbeth Dahl Department of Seafood and Nutrition, Institute of Marine Research,Bergen, Norway
  • Sigrun Henjum Department of Nursing and Health Promotion, Oslo Metropolitan University (OsloMet), Oslo, Norway
  • Jan Alexander Division of Infection Control, Environment and Health, Norwegian Institute of Public Health, Oslo, Norway
  • Patrick-Andre Korneliussen Department of Seafood and Nutrition, Institute of Marine Research,Bergen, Norway
  • Lise Madsen Department of Seafood and Nutrition, Institute of Marine Research,Bergen, Norway, and Department of Biology, University of Copenhagen, Copenhagen Ø, Denmark
  • Marian Kjellevold Department of Seafood and Nutrition, Institute of Marine Research,Bergen, Norway
Keywords: Iodine, Recommended Intake, Tolerable Upper Intake Level, Public Health, Seaweed, Kelp, Macroalgae, Iodine ecxess, Novel Food


Background: Seaweeds and kelps, also known as macroalgae, have long been common in the East-Asian diet. During recent years, macroalgae have entered the global food market, and a variety of macroalgae products are now available for consumers. Some macroalgae species are known to be particularly rich in iodine, but little data regarding the iodine content of macroalgae-containing foods exists.

Objective: The aim of this research study was to analyse the iodine content in a large variety of commercially available macroalgae-containing foods and supplements and to evaluate whether such products are sources of adequate dietary iodine.

Design: Ninety-six different products were collected after surveying the Norwegian market for commercially available macroalgae products, collected from three categories: 1) wholefood macroalgae products (n = 43), 2) macroalgae-containing foods (n = 39), and 3) dietary supplements containing macroalgae (n = 14). All products were analysed for iodine content by inductively coupled plasma-mass spectrometry (ICP-MS).

Results: The iodine content in one portion of wholefood macroalgae products ranged from 128 to 62,400 μg. In macroalgae-containing foods, the iodine content ranged from 30 to 25,300 μg per portion, and in supplements it ranged from 5 to 5,600 μg per daily dose. The species with the highest analysed iodine content were oarweed, sugarkelp and kombu, with mean iodine levels of 7,800, 4,469 and 2,276 μg/g, respectively. For 54 products, the intake of one portion or dose would exceed the tolerable upper intake level (UL) for iodine.

Discussion and conclusion: The iodine content in the included products was variable and for most products high, exceeding the tolerable upper intake level (UL) if consumed as a serving or portion size. The labelling of macroalgae species included, and declaration of iodine content, were inadequate or inaccurate for several products. As macroalgae-containing products are unreliable iodine sources, inclusion of such products in the diet may pose a risk of consuming excessive amounts of iodine.


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How to Cite
Aakre I., Doblaug Solli D., Wik Markhus M., K. Mæhre H., Dahl L., Henjum S., Alexander J., Korneliussen P.-A., Madsen L., & Kjellevold M. (2021). Commercially available kelp and seaweed products – valuable iodine source or risk of excess intake?. Food & Nutrition Research, 65.
Original Articles