Researchers from the University of Glasgow looked at 224 products containing seaweed on the UK market and found just 22 of these stated iodine content on packs.
Writing in the journal Foods, they said while edible algae were not a staple part of the Western diet, the expansion of the health-food industry had led to a “resurgence” of seaweed in the British diet.
Failing to label the iodine not only missed this opportunity to improve currently insufficient iodine intakes, it could also have the negative affect of exceeding recommended upper intake levels.
The main dietary sources of iodine in the UK were dairy products, mainly milk and seafood. Yet the researchers said fish consumption in Britain was low and milk consumption falling.
While WHO recommendations for universal salt iodisation saw 130 countries doing so by 2007, this was not the case in the UK and availability of iodine-rich salt there was low.
Echoing conclusions from the European Food Safety Authority (EFSA) in 2014, they said this held risks such as toxicity from high iodine levels or accumulation of arsenic, heavy metals and contaminants.
For 40 of the products it was possible for the researchers to estimate iodine content, which showed average levels of 585 microgram (μg) per estimated serving. Whilst these servings were only estimated, 26 products could potentially lead to an iodine intake above the EU tolerable adult upper level of 600 μg per day.
“The lack of information regarding the seaweed type used, its source and iodine content makes it difficult to formulate safe conclusions regarding the safety and suitability of these products and is a potential issue for high iodine exposure, especially for consumers who are pregnant,” the researchers wrote.
They said more information was needed on the source of seaweed, water quality and how it was processed to assess potential exposure to contaminants and toxic compounds.
“Owing to the nutrient density and the potential use of seaweed as a functional ingredient, this information would enhance its safe use and magnify the potential accompanied health benefits of edible algae. There is additional scope to study consumer purchase behaviour in relation to seaweed products, in terms of demographics and drivers for purchase.”
Vol. 4 Iss. 2, pp. 240-253, doi: 10.3390/foods4020240
“Emergence of Seaweed and Seaweed-Containing Foods in the UK: Focus on Labeling, Iodine Content, Toxicity and Nutrition”
Authors: M. Bouga and E. Combet