Seaweed superfoods: 7 types worth knowing
Seaweed is one of humanity’s oldest superfoods. Vikings, Celts, Japanese and Polynesian communities all ate it. Today, research backs up that traditional wisdom: seaweed is a concentrated source of iodine, minerals and antioxidants that support normal thyroid function, immunity and skin.
It’s a useful part of the diet, especially where iodine intake tends to be low. Two or three times a week is plenty — add it to smoothies, miso soup or salads instead of salt.
Here are the main types, what they offer and who should be careful.
1. Sea moss (Irish moss)
A red seaweed, usually sold dried or as a gel. Grows in the Atlantic and is rich in carrageenan. What it offers: supports digestion and immunity; contains many minerals (calcium, magnesium, iodine, potassium); antioxidant. Be careful: too much iodine can affect the thyroid; allergies and heavy-metal contamination are possible. Not suitable for people with thyroid conditions or on blood thinners. Can cause nausea if you have too much.
2. Spirulina
A blue-green freshwater alga (cyanobacterium), usually sold as powder or tablets. Eaten by the Aztecs. What it offers: rich in protein (up to 60%), vitamins A, B, E and K, and iron. Supports immunity and has antioxidant properties; its effects on cholesterol and blood sugar are being studied. A great protein source. Be careful: poor-quality products can contain toxins (microcystins) from contaminated water. Not recommended with autoimmune conditions, during pregnancy or breastfeeding, or with phenylketonuria. May cause nausea or headaches.
3. Chlorella
A green freshwater alga, sold as powder or tablets. What it offers: high in chlorophyll, protein, vitamins B12 and C, and minerals. Supports immunity, has antioxidant properties and supports skin and digestion. Be careful: can cause diarrhoea, nausea or bloating, and allergies to iodine or mould. Not suitable if your immune system is weakened or if you take warfarin (it contains vitamin K). May contain heavy metals.
4. Kelp
A brown seaweed from cold waters, often sold dried or as powder. What it offers: a source of iodine, potassium and iron; supports normal thyroid function and digestion; antioxidant. Be careful: very high in iodine. If you have a thyroid condition, kidney problems or high blood pressure, or take blood thinners, talk to your GP first.
5. Nori
A red seaweed sold as dried sheets for sushi. What it offers: contains omega-3, vitamins A, C and B12, and minerals; supports heart health, immunity and skin; low in calories. Be careful: allergies are rare but possible. It’s high in sodium, which matters if you have high blood pressure. Cheaper products may contain heavy metals.
6. Wakame
A brown seaweed used in salads and soups. What it offers: a source of fucoidan (being actively researched), iodine and calcium; supports healthy hair and skin. Be careful: excess iodine; can accumulate heavy metals. Talk to your GP first if you have a thyroid condition or take blood thinners.
7. Dulse
A red seaweed, eaten dried or fresh. What it offers: high in protein, potassium and iron; supports heart health and immunity; antioxidant; supports digestion. Be careful: the high potassium content can be a problem for people with kidney disease or electrolyte imbalances. Allergies are possible, as is a build-up of iodine and heavy metals.
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General information only, not medical advice. If you have a thyroid or kidney condition or take medication, please talk to your GP before adding seaweed or seaweed supplements.
It’s a useful part of the diet, especially where iodine intake tends to be low. Two or three times a week is plenty — add it to smoothies, miso soup or salads instead of salt.
Here are the main types, what they offer and who should be careful.
1. Sea moss (Irish moss)
A red seaweed, usually sold dried or as a gel. Grows in the Atlantic and is rich in carrageenan. What it offers: supports digestion and immunity; contains many minerals (calcium, magnesium, iodine, potassium); antioxidant. Be careful: too much iodine can affect the thyroid; allergies and heavy-metal contamination are possible. Not suitable for people with thyroid conditions or on blood thinners. Can cause nausea if you have too much.
2. Spirulina
A blue-green freshwater alga (cyanobacterium), usually sold as powder or tablets. Eaten by the Aztecs. What it offers: rich in protein (up to 60%), vitamins A, B, E and K, and iron. Supports immunity and has antioxidant properties; its effects on cholesterol and blood sugar are being studied. A great protein source. Be careful: poor-quality products can contain toxins (microcystins) from contaminated water. Not recommended with autoimmune conditions, during pregnancy or breastfeeding, or with phenylketonuria. May cause nausea or headaches.
3. Chlorella
A green freshwater alga, sold as powder or tablets. What it offers: high in chlorophyll, protein, vitamins B12 and C, and minerals. Supports immunity, has antioxidant properties and supports skin and digestion. Be careful: can cause diarrhoea, nausea or bloating, and allergies to iodine or mould. Not suitable if your immune system is weakened or if you take warfarin (it contains vitamin K). May contain heavy metals.
4. Kelp
A brown seaweed from cold waters, often sold dried or as powder. What it offers: a source of iodine, potassium and iron; supports normal thyroid function and digestion; antioxidant. Be careful: very high in iodine. If you have a thyroid condition, kidney problems or high blood pressure, or take blood thinners, talk to your GP first.
5. Nori
A red seaweed sold as dried sheets for sushi. What it offers: contains omega-3, vitamins A, C and B12, and minerals; supports heart health, immunity and skin; low in calories. Be careful: allergies are rare but possible. It’s high in sodium, which matters if you have high blood pressure. Cheaper products may contain heavy metals.
6. Wakame
A brown seaweed used in salads and soups. What it offers: a source of fucoidan (being actively researched), iodine and calcium; supports healthy hair and skin. Be careful: excess iodine; can accumulate heavy metals. Talk to your GP first if you have a thyroid condition or take blood thinners.
7. Dulse
A red seaweed, eaten dried or fresh. What it offers: high in protein, potassium and iron; supports heart health and immunity; antioxidant; supports digestion. Be careful: the high potassium content can be a problem for people with kidney disease or electrolyte imbalances. Allergies are possible, as is a build-up of iodine and heavy metals.
Want a plan that fits your body and your routine? Book a session →
General information only, not medical advice. If you have a thyroid or kidney condition or take medication, please talk to your GP before adding seaweed or seaweed supplements.
