Sea Lettuce

(Ulva sp.)

Sea lettuce is the most common green seaweed (no it’s not a plant!) that can be found on our shores. Sea lettuce is not just one species but is, like kelp and nori, used as a collective name for a number of different species that look very much similar to each other. Some of them can only properly be identified using a microscope. They are only one or two cells thick, and can differ a lot in shapes, from oval to round to thick and thin. With holes or without, it comes as it grows.

Sea lettuce can be found on the higher part of the intertidal where it can cover large areas in a green mat. This may especially the case in areas with high nutrient content such as near rivers with runoff from farms and sewage outlets. Care must therefore be taken when picking.


Fresh, sorrel-like

Nutritional benefits

Nutritional info of Ulva lactuca (left) and Ulva intestinalis (right), two of the most commonly encountered Ulva species in Cornwall.

Health Benefits

Just like Nori and Dulse, Sea lettuce is very high in polysaccharides, which can reach 65% of their dry weight. The polysaccharide Ulvan is thought to have anti-influenza properties and is used in the treatment of gastric ulcers. Some of the health benefits attributed to Sea lettuce and compounds therein:

  • Anticancer properties
  • Antioxidative properties
  • Anti-herpetic properties
  • Anti-tumor action
  • Anticoagulative properties
  • Reduction of total cholesterol, free cholesterol, triglyceride and phospholipid in the liver
  • Anti-hypertension effect
  • Dietary fibre for maintenance of human health
  • Anti-diabetic properties
  • Anti-obesity
  • Anti-ulcer, treatment of gastritis and gastroduodenal ulcers
  • Promotes regeneration of the mucous membranes and suppresses inflammation in the stomach, and restoration of intestinal biocenosis
  • Anti-toxic effects on hepatitis
  • May prevent primordial atherosclerosis
  • Kill tumour cells directly through type 1 Th1 cell and NK cell responses
  • Antiviral properties
  • Anti-HIV properties
  • Prebiotic properties
  • Antibacterial properties against E. coli and Staphylococcus
  • Antibiotic properties
  • Used to treat tbc


  • Improves skin condition
  • Stimulates production and repair of collagen and elastine
  • Hydrating
  • Rejuvenating
  • Increases skin vitality

Buy Sea Lettuce (part of the Sea Salad)