E400 - Alginic acid

At a glance

Alginic acid is a plant-derived fiber from brown algae. It is used to thicken, stabilize, and sometimes emulsify foods so they keep a consistent texture. ¹²

Why is alginic acid added to food?

Food makers use alginic acid to control texture and stability. It helps:

• Thicken sauces, dressings, and dessert mixes so they pour and coat evenly. ¹
• Stabilise emulsions (oil-and-water mixtures) and keep particles from settling. ¹
• Hold water to improve juiciness and reduce syneresis (weeping) in gels and fillings. ²

Chemically, alginic acid is a linear polysaccharide built from mannuronic and guluronic acid units; this structure lets it bind water and form gels with certain minerals, which is why it is so effective in texture control. ³

What foods contain alginic acid?

You’ll most often see alginic acid (or its alginate salts) in:

• Ice cream, sorbets, and dairy or plant-based desserts
• Sauces, gravies, and salad dressings
• Fruit fillings, jams, and jellies
• Processed cheese and cheese spreads
• Bakery icings and toppings
• Plant-based drinks and shakes

These are typical use categories noted in EU evaluations and exposure assessments. ¹

What can replace alginic acid?

Several hydrocolloids can provide similar texture or stability, depending on the recipe:

• Its close relatives: sodium alginate, potassium alginate, and calcium alginate
• Plant gums: guar gum and acacia gum
• Microbial gum: xanthan gum
• Seaweed extract: carrageenan
• Fruit pectin: pectins
• Fibers: cellulose

Each behaves a bit differently, so formulators often test small blends to match mouthfeel, freeze–thaw stability, or heat tolerance. ¹

How is alginic acid made?

Alginic acid is extracted from brown seaweeds (such as kelp). Manufacturers typically:

1. Clean and chop the seaweed; 2) Extract alginates with an alkaline solution; 3) Filter to remove solids; 4) Precipitate alginic acid by acidifying the extract; 5) Wash and dry the product to the required purity. ²

EU specifications describe its identity, purity, and how it is produced from seaweed sources. ²

Is alginic acid safe to eat?

Based on a comprehensive review, the European Food Safety Authority (EFSA) concluded there is no safety concern for alginic acid (E400) at current authorised uses and use levels. ¹ Alginic acid is not absorbed intact in the gut and is considered of low toxicity. ¹

At very high intakes, some people may experience mild gastrointestinal effects such as increased stool bulk or bloating, which is typical for non-digestible fibers. ¹

Does alginic acid have any benefits?

In foods, alginic acid helps deliver consistent texture, reduces separation, and can improve freeze–thaw stability in frozen desserts. As a largely non-digestible fiber, it contributes minimal calories. ¹

Who should avoid alginic acid?

Most people can consume alginic acid without issues. Those who are sensitive to a sudden increase in dietary fiber (for example, people prone to gas or bloating) may prefer to moderate intake. For very young infants and certain medical diets, thickening agents in general should only be used as directed by a healthcare professional. ¹

Because alginic acid is derived from seaweed, it is generally suitable for vegetarian and vegan diets. ²

Myths & facts

• Myth: “Alginic acid is synthetic.”
  Fact: It is obtained from brown seaweeds and refined to food-grade purity. ²
• Myth: “It’s the same as MSG.”
  Fact: Alginic acid is a seaweed fiber; monosodium glutamate (MSG) is a flavor enhancer. They are unrelated additives.
• Myth: “It’s always a gelling agent.”
  Fact: Alginic acid mainly thickens and stabilises; strong gels usually form when alginates interact with calcium or other ions, or when using related salts like calcium alginate. ¹

Alginic acid in branded foods

You’re most likely to find E400 on labels for ice creams, sauces, processed cheese spreads, and fruit fillings. Look for “alginic acid,” “alginates,” or “E400–E404” in the ingredient list; many brands use it to keep products smooth and stable across shelf life. Availability and recipes vary by region and product style. ¹

References

Footnotes

1. Re-evaluation of alginic acid and its salts (E 400–E 404) as food additives — EFSA Journal. https://www.efsa.europa.eu/en/efsajournal/pub/5049 ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹²

2. Commission Regulation (EU) No 231/2012 laying down specifications for food additives listed in Annexes II and III to Regulation (EC) No 1333/2008 — EUR-Lex. https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32012R0231 ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶

3. Alginic acid — PubChem (NIH). https://pubchem.ncbi.nlm.nih.gov/compound/Alginic-acid ↩