Health & Beauty Benefits Of Seaweed: Sweet Kombu
Health & Beauty Benefits of Seaweed: Sweet Kombu (Saccharina latissima)
Seaweed: The hope from the sea
Newsletter No. 1 / 2026
We are starting a series of newsletters describing some seaweed species (macroalgae) that anyone can gather themselves from the shores of the
Atlantic Ocean coast of Ireland and Europe.
Every month, at the full or new moon, you can walk along the shore at low tide and check if the deep rocks have revealed your favourite seaweed.
Tide times information at https://www.tidesnear.me/
Discovering
Saccharina latissima
Common names: Sweet Kombu, Sugar Kelp.
First, for the novice foragers,
I wish to list these important rules on seaweed harvesting:
- Never eat dead seaweed that has been washed up on the beach after a storm. It will have absorbed more heavy metals (pollutants) and will have lost most of its important health properties and related benefits.
- If you buy dried seaweed, rinse it well in fresh running water for at least 10 minutes. Don't soak seaweed for hours, because it might start to rot.
- Freshly harvested seaweed can be eaten or cooked immediately, after a quick rinsing. If you can't use it immediately, store it in the freezer, or dry it in the oven at a low temperature.
Now, let’s talk about
Saccharina latissima (Sweet Kombu or Sugar Kelp)
It is a brown seaweed that is not only ecologically fascinating but also packed with potential for food, health, and beauty applications.
From its natural habitats to its role in traditional cultures and modern research, let's explore what makes this species so special.
Where Does It Grow?
Saccharina latissima thrives in cold, temperate waters across the North Atlantic and North Pacific.
It's commonly found along rocky shores in sheltered bays, from the sublittoral fringe down to depths of about 30 meters or more, in clearer offshore waters.
In Europe, it's widespread from Portugal to the Arctic, including Ireland, the British Islands, Scandinavia, and Iceland.
On the North American side, it ranges from Alaska to California and along the Atlantic coast from Greenland to New York.
It prefers hard substrates like rocks, boulders, or even clam shells, and tolerates brackish conditions but avoids highly wave-exposed areas.
Growth on the West Coast of Ireland
On Ireland's west coast, sugar kelp starts its rapid growth phase in late winter to early spring, peaking around March to May with rates up to 0.34 grams per day in dry weight.
The growing season aligns with increasing daylight and nutrient availability, slowing by late summer as temperatures rise and nutrients decline. Harvesting typically occurs in spring to early summer.
Traditional Uses in Ireland and Atlantic Europe
In Ireland and other Atlantic European countries like Scotland, France, and Norway, sugar kelp has been harvested for centuries as fertilizer for crops like potatoes and cabbage, thanks to its rich mineral content.
During famines, such as the Irish Potato Famine in 1847, coastal communities turned to seaweeds including kelps for sustenance.
It was also used in animal feed and as a medicinal remedy due to its high iodine.
In broader European traditions, it served as a food source in Celtic regions, though less commonly than red seaweeds like dulse.
The Meaning Behind "Saccharina" and Its Sugars
The genus name "Saccharina" derives from the Latin for "sugary," reflecting the sweet-tasting mannitol that forms a white powder on dried fronds.
It doesn't contain "a lot" of table sugar (sucrose), but it's rich in polysaccharides like laminarin and mannitol, which give it a mildly sweet flavor.
These are not simple sugars but complex carbs that contribute to its nutritional profile.
Differences Between Seaweed Sugars and Table Sugar
Sugars in sugar kelp, like mannitol (a sugar alcohol) and laminarin (a beta-glucan), differ from table sugar (sucrose).
Mannitol is less caloric, doesn't spike blood sugar as much, and acts as a prebiotic for gut health.
Laminarin is a storage polysaccharide, not easily digested by humans but fermented by gut bacteria into beneficial short-chain fatty acids.
In contrast, sucrose is a simple disaccharide that provides quick energy but can contribute to health issues like obesity if overconsumed.
Seaweed sugars offer fiber-like benefits without the rapid glucose release.
Growth Season and Shore Depth
Growth begins in late winter/early spring, with peak rates in spring (up to 1.1 cm/day) and spores released in autumn/winter.
It typically inhabits depths from the low intertidal to 30 meters, where light penetrates well.
In Ireland, it's found in sheltered infralittoral zones.
Main Compounds and Health Benefits
Saccharina latissima is nutrient-dense, with varying compositions.
Key compounds:
- Potassium (up to 62,088 mg/kg): Supports heart health and blood pressure regulation.
- Calcium (up to 8,236 mg/kg): Essential for bones and muscles.
- Magnesium (up to 6,041 mg/kg): Aids energy production and nerve function.
- Iron (up to 35 mg/kg): Prevents anemia; higher in spring harvests.
- Copper: Boosts immune function.
- Boron: Supports bone health.
- Glucose (in laminarin): A beta-glucan prebiotic, unlike table sugar's quick energy; promotes gut health without spikes.
- Xylose, Fucose, Glucuronic acid: In fucoidans; anti-inflammatory, antiviral.
- Alginate: Fiber-like; aids digestion, weight management.
Other benefits: Antioxidants reduce oxidative stress; iodine for thyroid health (but monitor intake);
omega-3s for heart/brain.
Overall, it enhances immunity, gut microbiota, and metabolic health.
|
Compound |
Content Range (mg/kg unless noted) | Health Properties |
| Potassium | 62,088 | Blood pressure, heart rhythm |
| Calcium | 8,236 | Bone strength, muscle contraction |
| Magnesium | 6,041 | Energy metabolism, relaxation |
| Iron | 35 | Oxygen transport, energy |
| Copper | Trace | Immunity, antioxidant enzymes |
| Boron | Trace | Hormone balance, bones |
| Glucose (in laminarin) | Varies (beta-glucan form) | Gut health vs. table sugar's rapid absorption |
| Xylose | In polysaccharides | Prebiotic potential |
| Fucose | 4-7 mol% | Anti-viral, skin health |
| Glucuronic acid | In alginates/fucoidans | Detoxification, anti-inflammatory |
| Alginate | 20-40% | Cholesterol reduction, satiety |
Use in Cosmetics
(INCI: Saccharina Latissima Extract – as Skin Conditioning Ingredient)
Saccharina latissima seaweed is used in cosmetics for its moisturizing, anti-aging, and protective properties (see INCI Ingredients list on the EU Portal).
It hydrates skin, reduces oiliness, and shields against pollution and UV stress.
It leverages polysaccharides like alginates for film-forming and soothing effects.
Key Research on Saccharina latissima
Studies show it adapts to warming oceans but faces limits in southern ranges (Diehl et al., 2023; Frontiers in Marine Science, 2021).
Bioactive compounds like fucoidans exhibit anti-inflammatory and antioxidant effects (Vasconcelos et al., 2024).
Microbial studies reveal its microbiome's role in health (Burgunter-Delamare et al., 2023).
For NASH models, it reduces liver inflammation (Kim et al., 2021).
How do I cook it?
This is how the dried seaweed looks like
And this is the look when it is freshly harvested or rinsed
How to cook and eat it:
- Rinse the seaweed for a few minutes with fresh water.
- Dry it in a low-temperature oven until crispy. (Alternatively, you can chop it finely and add it fresh to stews, sauces, etc.)
- The crispy seaweed can be easily flaked and added to salads. If you wish to add more flavour to your crispy Sweet Kombu, sprinkle it with a spice of your choice while it is still wet, such as paprika, wasabi, or chilli, before drying. It makes a delicious snack to serve with risotto, pasta or on pizza.
How to use it as a homemade cosmetic:
- Rinse the seaweed for a few minutes with fresh water.
- Boil it in a small amount of fresh water until most of the water has evaporated and it forms a light gel.
- When the gel is lukewarm, add a spoonful of fresh lemon juice and mix well.
- You can preserve the gel in the freezer.
- To have it ready when you need it, freeze the gel in a plastic ice cube tray.
- Every morning, you can take a seaweed ice cube, wrap it in a cloth, and massage your skin with it until it has completely melted.
Please send any questions or requests for further information (or to stop receiving our monthly Newsletter) to:
rosaria@algaran.ie
I will reply privately to all your questions.
If you would like to receive my favourite "part Irish and part Mediterranean" recipes, just let me know. I will publish a video showing all the stages of preparation.
Algaran Seaweed
Malinmore, Glencolmcille
Co. Donegal Ireland
Tel. 00353 749730773
www.seaweedproducts.ie