Photo: Cwmhiraeth, CC BY-SA 3.0 (via Wikimedia Commons)

Sugar Kelp

Saccharina latissima

Also known as Sugar Kelp, Sea Belt, Devil's Apron, Sugar Wrack, Atlantic Kombu

At a glance

Family

Laminariaceae

Type

Brown algae (marine kelp)

Parts used

Blade (frond)

Size

Blades typically 1 to 4 meters (3 to 13 feet) long, occasionally longer

Bloom

No true flowers; as a brown algae it produces spore-bearing patches called sori on mature blades in late summer

Habitat

Cold, clear coastal waters of the North Atlantic and North Pacific, anchored by a holdfast to rocks and hard seabed in the subtidal zone

Acquisition

Forage

Traditional remedies in HerbSense

Key benefits

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Rich source of iodine

Traditional thyroid support

Mineral-dense sea vegetable

Deepens savory broths

Traditional uses

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Along the rocky shores of the North Atlantic, from Norway to Scotland to New England, coastal families have gathered sugar kelp for generations, drying it in ropes on fences and rooflines to see them through winter. It was eaten as a vegetable, worked into broths and stews, fed to livestock, and dug into thin coastal soil as fertilizer when little else would grow. Long before iodized salt reached inland kitchens, seaweeds like this one were the quiet, dependable source of iodine for people living by the sea, and it has traditionally been used to support a healthy thyroid and to address the swelling of the neck once known simply as goiter. In Japan and along the Pacific coast, close relatives of this kelp became the foundation of dashi, the savory broth beneath so much of that cuisine.

How to grow & use it

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The full apothecary for Sugar Kelp

Traditional remedies and step-by-step preparations, a complete growing guide, and how to harvest, dry, and store it, all unlocked with HerbLens Unlimited.

✦Remedies & preparations
✦ Growing guide
✦Harvest & storage

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Pairs well with

✦Dulse
✦Nettle
✦Ginger

Substitutes

✦Kombu (Saccharina japonica)
✦Bladderwrack

Choose it when

“For the mineral hush of the tide, and a broth with roots older than written recipes.”

Did you know?

The white, faintly sweet crust that forms on dried sugar kelp is mannitol, a natural sugar alcohol, and it is the very thing that earned this kelp its common name, since foragers along the shore would break off a dried strip and find it tasted faintly sweet.

Safety

Sugar kelp is very high in iodine and can affect thyroid function with frequent heavy use, especially for those with thyroid conditions. It's best avoided in large amounts during pregnancy, since a developing thyroid is sensitive to iodine excess. It can also concentrate arsenic from seawater, so use modest amounts from a tested source, and those on blood-thinning medication should note its vitamin K content.