How seaweed can help vegans ingest sufficient iodine

The marine plant can be a useful source of the mineral for those who avoid dairy and fish, but too much could also be harmful to health.

13 August 2018
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image credit: chengyuzheng via Getty Images

Meet the Expert

Who: Dr. Laura Wyness

What: Independent registered nutritionist


There has been an increase in food products incorporating seaweed in recent years – as Food Spark has previously noted here and here. As well as providing a source of iodine and natural bioactive compounds, the plant can be used as a functional ingredient due to its satiating properties and its use in low sodium salts.

Iodine is needed to make thyroid hormones, which are required for many process throughout the body. Too much iodine can have negative impacts on thyroid hormone production; too little iodine can also be detrimental and may result in goitre. 

Dairy products and seafood are the main dietary source of iodine.  For the past 50 years or so, the UK population was considered to be iodine sufficient. However, data from recent surveys has led to increasing concerns that adequate iodine intakes are not being met, especially among pregnant women who have increased requirements.

Anyone who excludes or limits dairy and fish from their diet is at risk of iodine deficiency, especially as plant-based milk alternatives are not commonly fortified with iodine. 

Seaweed use in products

Including seaweed as a whole product or incorporating it into products can help increase the availability of iodine in our diet, as long as the levels of iodine are evaluated to avoid unintentional high doses. 

Seaweed has a variety of useful properties that could potentially enhance products. For example, it can increase satiety when added to beverages, breakfast bars and pizza, and can be used in low sodium salts. 

The use of the marine marvel has risen alongside the recent expansion of health foods. It can be found in a variety of areas, such as breads, biscuits, condiments, smoothies, spaghetti, salads, soups and crackers.

A survey of UK retailed products identified a total of 224 seaweed-containing products.

However, only 10% of these products clearly stated information on iodine content while another 18% of the products provided details that enabled iodine content to be estimated.

Proper labelling

Not all seaweed species have high iodine content, but the study found a range of products that could provide a higher iodine intake than the European Tolerable Upper Limit of 600µg/day.

Some types of seaweed are associated with risks, such as toxicity from high iodine levels or contaminants and heavy metals. 

Although, seaweed is labelled on products where present, information on the type used, its source, processing and iodine content is often lacking. This should be more carefully addressed, because while a certain amount of iodine is beneficial, high levels, particularly among pregnant women, should be avoided due to the potential harmful effects.

Information on the source of the seaweed and how it was processed would also help determine potential exposure to contaminants and toxic compounds.  

Though it’s use as a sustainable, nutrient-rich foodstuff is laudable, it’s important not to rush headlong into development without a clear idea of the cons as well as the pros.

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