E-numbers / Thickeners & emulsifiers / E401
also: Algin · Sodium salt of alginic acid
A thickener and setting agent made from brown seaweed. It gives ice cream, sauces and desserts a smooth, stable texture.
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Egg, Butter (Milk), Sugar, Cocoa Mass, Egg Yolk, Cocoa Butter, Natural Flavouring, Emulsifiers: Soya Lecithin, Carrageenan, Sodium Alginate, Potassium Sorbate (Preservative)
Sodium alginate is a salt of alginic acid, a fibre found in the cell walls of brown seaweeds such as kelp.
465
of the 43,325 UK supermarket foods we checked declare E401 in their ingredients
That is 1.1%, counted by its code or its name.
Counted by NutraSafe from UK supermarket ingredient lists, September 2026. How we counted
Sodium alginate is a salt of alginic acid, a fibre found in the cell walls of brown seaweeds such as kelp. It is taken from dried seaweed and dried into a white or pale cream powder. It is a kind of dietary fibre and passes mostly undigested through the gut.
Dissolved in water it makes a thick gel. It stops oil and water separating and thickens liquids. With calcium it sets into a firm gel without heating, which is how chefs make jelly spheres and how makers shape formed food. It can also form a thin coat on fruit and vegetables.
Ice cream, dairy desserts, salad dressings, sauces, cheese alternatives, tinned fruit, formed meat and fish such as reformed scampi, beer and wine making, and a thin coat on some loose fruit and vegetables. Labels call it sodium alginate or E401.
Sodium alginate counts as dietary fibre. It is not digested in the small intestine and reaches the large bowel, where gut bacteria break some of it down. At the amounts in food, that is what any soluble fibre does.
European reviewers looked again at the alginates (E400 to E404), raised no toxicity issue at the levels allowed in food, and said no numerical daily limit was needed.
Alginates come from seaweed, which is rich in iodine, but cleaning and purifying removes almost all of it. European reviewers found very little iodine left in sodium alginate, not enough to add meaningfully to the iodine people eat.
Reviewers noted iodine carried over from seaweed alginates into food is negligible at the permitted levels.
In 2024 the UK Food Standards Agency assessed a new use of E401 as an edible coating on whole fresh fruit and vegetables. The UK's toxicity committee found no health risk from this use at the levels proposed.
The UK Committee on Toxicity reviewed sodium alginate as a coating on whole fresh fruit and vegetables and found no risk to health at the levels proposed.
Daily limit. None set.
People with a known seaweed or algae allergy should check labels for E401 or sodium alginate, though reactions to purified alginate are uncommon. People on an iodine-restricted diet do not need to count alginate as an iodine source at food levels.
Sodium alginate has been used in food for decades and has had a full European review, which found no basis for a numerical daily limit. It behaves like dietary fibre rather than a chemical that the body absorbs. Neither regulators nor the published research point to harm at the levels found in food.
No. Sodium alginate is approved in the UK. In 2024 its permitted uses were extended to a coating on whole fresh fruit and vegetables.
It is taken from brown seaweed, not made from petroleum. Whether a product can be called natural depends on labelling rules, but the raw material is a seaweed fibre.
Ice cream, dairy desserts, cheese alternatives, salad dressings, tinned fruit, formed fish such as reformed scampi, and increasingly a thin coat on loose fruit and vegetables. Labels call it sodium alginate or E401.
Yes. It comes from seaweed, with nothing from animals.
Last reviewed: 20 June 2026
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