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Is sea moss a superfood?

What you hear: “Sea moss contains 92 of the 102 minerals your body needs, making it a superfood everyone should eat.”

What the studies found

We found no clinical trials testing whether sea moss (Irish moss, a red seaweed) improves any health outcome in people. The US National Library of Medicine's drug and breastfeeding database states that no medicinal value has been proven. Like other seaweeds, it contains iodine and can carry heavy metals such as arsenic, lead, cadmium and mercury from the water it grew in. A 2026 test of 66 sea moss products sold online found arsenic, cobalt and mercury in dried sea moss, and bacteria including Salmonella in some products. The body needs a small set of essential minerals, not 102, and we found no published analysis behind the '92 minerals' figure.

Take care: Seaweed iodine levels vary wildly and can push intake past safe limits, which can upset the thyroid; it is best avoided while breastfeeding or with thyroid disease unless a doctor agrees.

What you could do

Enjoy seaweed occasionally as food if you like it, and get minerals from a varied diet rather than sea moss gels or capsules.

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Not medical advice. General information from published studies, not a diagnosis or a treatment plan. Talk with your doctor before starting a supplement or changing a medicine, especially if you are pregnant, take other medicines or have a health condition.

How we judged it

Not proven: Not enough good human evidence yet, either way. We judge the claim as it is usually said online, not the habit itself. Trials assign people at random, so they can show cause; observed studies follow people and show a link, not proof. Last checked: October 2026.

The studies, in their own words

1. Drugs and Lactation Database (LactMed): Sea Moss. NLM 2006-

   Sea moss or Irish moss (Chondrus crispus) is a type of red seaweed that is used as food and medicine, although no medicinal value has been proven.

2. Drugs and Lactation Database (LactMed): Sea Moss. NLM 2006-

   It also contains numerous minerals, including iodine and some toxic heavy metals such as arsenic, lead, cadmium and mercury that come from the water where it was grown.

3. Rejuso et al. J Food Prot 2026

   Arsenic, cobalt, and mercury were detected in dried sea moss, whereas arsenic and cobalt were below the limits of detection in the gels and mercury was detected at trace concentrations.

4. Aakre et al. Food Nutr Res 2021

   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.

5. Taylor et al. Clin Endocrinol (Oxf) 2026

   Endocrinologists now face a dual challenge: widespread under-recognition of population iodine insufficiency and a growing minority of patients presenting with iodine-induced thyroid dysfunction.

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