Seaweed has been eaten for centuries in coastal cultures, particularly in Japan, Korea and parts of China, where it is valued for both flavour and nutrition. In recent years, seaweed has gained attention in the wellness world for its connection to thyroid health — but this relationship is often misunderstood.
If you’ve heard that seaweed is “good for the thyroid” or, conversely, that it should be avoided altogether, the truth sits somewhere in between. Here’s what you need to know.
The Thyroid & Why Iodine Matters
The thyroid is a small, butterfly-shaped gland in the neck that plays a major role in regulating metabolism, energy levels, body temperature and hormone balance.
To function properly, the thyroid needs iodine, a trace mineral the body cannot make on its own. Iodine is used to produce the thyroid hormones T3 and T4, which influence almost every cell in the body.
In Australia, iodine intake is generally adequate due to iodised salt and fortified bread, but mild deficiency can still occur — particularly in people who:
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Avoid processed foods and iodised salt
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Follow plant-based or dairy-free diets
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Live inland and eat little seafood
This is where seaweed often enters the conversation.
Seaweed as a Natural Source of Iodine
Seaweed is one of the richest natural sources of iodine available. However, not all seaweeds are equal. Iodine content varies dramatically by species.
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Kombu and native Australian kelp species: Generally very high in iodine when in its raw or dried state
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Wakame / Undaria: Moderate iodine levels
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Nori: Relatively low iodine compared to kelps
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Sea lettuce & green seaweeds: Generally lower and more variable
This variability is important. While iodine deficiency can impair thyroid function, excess iodine can also disrupt the thyroid, particularly in people with existing thyroid conditions.
Can Seaweed Support Thyroid Health?
Seaweed can support thyroid health when consumed in appropriate amounts, as part of a balanced diet.
Potential benefits include:
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Providing iodine in a whole-food form
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Supplying other thyroid-supportive nutrients such as selenium, iron, zinc and tyrosine (depending on species)
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Offering antioxidants and polysaccharides that support overall metabolic health
In cultures with long traditions of seaweed consumption, intake is typically small but regular, not excessive.
When Caution Is Needed
Seaweed is not a one-size-fits-all food.
You should be cautious with seaweed if you:
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Have hyperthyroidism, Hashimoto’s disease, or other diagnosed thyroid disorders
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Are taking thyroid medication
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Are pregnant or breastfeeding (iodine needs change during these stages)
In these cases, iodine intake should be discussed with a healthcare professional. Seaweed should not be used as a therapeutic treatment or supplement unless advised.
How to Enjoy Seaweed Mindfully
If you’re including seaweed for general nutrition rather than targeted therapy, moderation is key.
Tips:
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Use seaweed as a condiment or flavour enhancer, not a staple food. Our Furikake and Chilli Kelp are good examples of blended seaweed products that deliver excellent health benefits without overloading on iodine.
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Rotate different species rather than relying on one type
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Be mindful of portion size, especially with kombu and native Australian kelps
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Choose sustainably harvested, food-grade seaweed
A sprinkle here, a spoonful there — not large daily servings.
The Bottom Line
Seaweed can play a role in supporting thyroid health, but it’s not a magic solution — and more is not better. Its value lies in small, thoughtful amounts, enjoyed as part of a diverse diet.
Like many powerful natural foods, seaweed is best respected for its potency. When used wisely, it offers flavour, minerals and a meaningful connection to traditional food cultures that understood balance long before nutrition labels existed.
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