Sodium alginate

Sodium alginate is the sodium salt of alginic acid, a natural polysaccharide extracted from brown seaweed. As a food additive (E401), it functions as a thickener, stabiliser, and gelling agent. It is used in salad dressings, dairy products, restructured meat and fish products, ice cream, noodles, and fruit preparations. In the presence of calcium ions, sodium alginate forms firm gels — a property exploited in spherification and in the production of formed food products.

JECFA evaluated sodium alginate in 1975 and did not establish a numerical ADI, classifying it as not specified — indicating no toxicological concern at levels used in food. Alginates are not absorbed to any significant extent in the gastrointestinal tract and pass through the body largely intact, behaving as a dietary fibre.

Sodium alginate is approved globally, including in the EU (E401), the United States (GRAS), Japan, and Korea. It is one of the best-studied seaweed-derived food hydrocolloids and is widely used in health-conscious and functional food formulations. There are no known adverse effects in the general population at typical food-use concentrations. Consumers with iodine sensitivity may note that seaweed-derived ingredients can occasionally carry trace iodine, though levels in purified food-grade alginate are typically negligible.