Agar-agar (seaweed extract) is a polysaccharide that comes from several varieties of red algae. Agar is used in making ice creams, jellies, icings, preserves, and for thickening milk and cream. It can be used as a substitute for gelatin.

Agar, in rare situations, can be a mild allergen and acts as a laxative. It is on the GRAS list.

References

Anderson DM, Brydon WG, Eastwood MA, Sedgwick DM. Dietary effects of sodium alginate in humans. Food Addit Contam. 1991; 8:237-248. Okai Y, Higashi-Okai K, Ishizaka S, et al. Possible immunomodulating activities in an extract of edible brown alga, Hijikia fusiforme (Hijiki). J Sci Food Agric. 1998; 76:56-62.