Alginic acid

Alginic acid is a natural polysaccharide extracted from the cell walls of brown seaweed species such as Laminaria and Macrocystis. As a food additive it acts as a thickener, gelling agent, and stabiliser in products ranging from ice cream and fruit yoghurts to salad dressings and bakery fillings. When alginic acid or its salts come into contact with calcium ions, they form a firm insoluble gel — a property exploited in restructured food products and spherification techniques.

JECFA's ADI for alginic acid is "not specified," evaluated in 1975, reflecting its status as a largely unabsorbed, fermentable dietary fibre. It passes through the digestive tract with minimal systemic absorption, providing prebiotic benefits similar to other soluble fibres. Very high doses may produce a mild laxative effect consistent with any dietary fibre, but this is not a concern at food additive concentrations.

Alginic acid is approved universally in the EU, US (GRAS), UK, Australia, Japan, and Vietnam. It is the parent compound of the commercially important alginate family (E401 sodium alginate, E402 potassium alginate, E404 calcium alginate, E405 propylene glycol alginate), and its salts are more widely used than alginic acid itself. Consumers on plant-based or sustainable diets will find alginic acid among the most natural and environmentally conscious thickeners available, derived from renewable seaweed sources with no known safety concerns.