LAMINARIA SACCHARINA
Laminaria saccharina is the former scientific name for the seaweed now classified as Saccharina latissima — the species commonly known as sugar kelp, sea belt or sugarwrack. Both names refer to the same plant, and the older one is still widely used in older literature, supplement labelling and the seaweed trade.
Why the Name Changed
The species was reclassified in 2006, when molecular work showed that the Laminaria genus as it stood contained species that weren't as closely related as their appearance suggested. A group of them, including this one, were moved into the genus Saccharina.
Laminaria still exists as a genus — Laminaria digitata, oar weed, remains in it. So the two names aren't interchangeable across the family, only for this species.
Identifying It
A single long undivided blade — unlike the finger-like splits of oar weed — with a distinctive rippled or crimped edge and a wavy central band. Olive-brown, growing to three metres or more, attached by a branching holdfast.
It grows on rock at and below the low-tide line, preferring sheltered water with some current. Common all around Britain and Ireland, and across the North Atlantic and North Pacific.
Where the "Sugar" Comes From
Dried sugar kelp develops a white powdery bloom on its surface. This is mannitol, a sugar alcohol the plant produces — and it's the reason for both the common name and the seaweed's characteristic sweetness alongside its savoury depth.
The white coating is a sign of good drying, not spoilage. Don't wash it off.
Why It Tastes Savoury
Sugar kelp is high in free glutamate. When glutamate is present in a dish it registers as umami — the savoury quality that makes food taste rounded and complete.
This is the same principle behind Japanese kombu, a closely related kelp, and it's why kelps of this family form the base of dashi. Glutamate from seaweed was the original subject of umami research: Kikunae Ikeda isolated it from kombu in 1908 and named the taste.
Alginate
Sugar kelp is a commercial source of alginate, a polysaccharide extracted from brown seaweed cell walls and used across food manufacturing as a thickener, stabiliser and gelling agent — in ice cream, sauces, dressings and jellies. It's also used in wound dressings and in dental impression material.
Cultivation
Sugar kelp is the main species farmed in Scottish and Irish seaweed aquaculture, grown on suspended lines and harvested in spring. It grows fast, needs no feed, fertiliser or fresh water, and takes up nutrients from the water as it grows — which is why it's attracting attention as a low-input crop.
Iodine: An Important Caution
Sugar kelp is very high in iodine, and content varies enormously with season and location. Occasional culinary use — a strip in a stock, removed before serving — is not a concern.
Regular consumption of dried kelp, or of kelp supplements, is a different matter. Sustained high iodine intake disrupts thyroid function, and kelp supplements have been linked to documented cases of thyroid dysfunction.
This applies with particular force during pregnancy, where excess iodine can affect foetal thyroid development. Anyone who is pregnant, breastfeeding, or has a thyroid condition should take medical advice before using kelp regularly, and should not take kelp supplements without it.
Related
For cooking with it, see our page on sugar kelp. For the wider family, see oar weed and alaria, or the full guide to edible seaweed.
Seaweed has been a source of savoury flavour for centuries. Sozyë's sauces are brewed from a blend of wild Scottish seaweeds, harvested off the north coast of Scotland.