The uses of seaweed

With such an abundance of biomass on our shores, it would be unthinkable that we couldn’t use it. Seaweeds have formed the source of a multitude of different products, and are used in small amounts in thousands of other products. Almost 90 % of the time the whole seaweed isn’t used, rather the seaweed has been processed to create a ‘seaweed extract’ derived from cellular components such as the cytoplasm and the cell wall. It is important to remember that all seaweed extracts are recognised by governmental agencies to be harmless, and all are food-grade and above.

The main products created from seaweeds agars, alginic acid and carrageenans are discussed below, also the main uses in our daily lives each have their own subsections.


Agar is the best known usage of any seaweed refined product. Used as a bacteriological culture medium, high sterile grades are incredibly expensive, with lesser refined food grades forming the bulk of agar production. There are several main species which form sources of agar, Gelidium and Gracilaria are the most important genera, Ceramium, Phyllophora and several others are also less important sources.


Extracted from species such as Eucheuma and Chondrus, carrageenans are availible in a variety of different grades (aka purities). These different grades are availible in different categories such as potassium, sodium and calcium salts. Carrageenans fiind themselves used in many different ways the primary usage though is similar for all seaweed derived products, as a thickener or stabiliser. In industry the usages vary although it is used in the production of jellies, jams etc. Pretty much any food that requires a viscogenic texture.

In cosmetics, carrageenans are used in massive amounts, much more than thier counterparts (agars and alginates). Some examples include cosmetics that require thickening, such as toothpastes, soaps, sun screams and solid state deodorant sticks.


Alginic acid is commonly extracted from Laminaria, Ecklonia and Macrocystis. Alginates are primarily used as emulsifiers and emulsion stabilisers in creams and lotions, or as a biodegradiable lubricant.