E401 Sodium alginate

E401Thickeners & gumsOrigin: Plant

Get a personal answer

Pick your family’s diets in the bar above.

Every diet

VeganYes

Made from seaweed.

Gluten-freeYes

HalalYes

KosherYes

KetoYes

A fiber used in small amounts, so it adds no net carbs.

Low-FODMAPYes

The short answer

Sodium alginate (E401) is a seaweed extract that thickens food and sets instantly when it touches calcium. It's safe, vegan and fits every diet we check.

93/100

Generally safe

Fine for most people at normal amounts.

E-numberE401

Comes fromPlant

What it doesThickeners & gums

Glycemic index—

Daily limitNot set

Also calledSodium alginate, Alginate

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For your pantry

Starter kit

Molecular gastronomy spherification kit

Sodium alginate, calcium and the tools to make fruit caviar.

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Food-grade pouch

Sodium alginate powder

For thickening and for popping-boba recipes.

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Food-grade pouch

Calcium lactate powder

The calcium bath that sets alginate, with no bitter taste.

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Rules by country

🇺🇸 US FDAApproved

🇪🇺 European UnionApproved

🇨🇦 Health CanadaApproved

CaliforniaNo extra rules

Approved everywhere with no daily limit. EFSA re-checked the alginates in 2017 and found no safety concern.

Daily limit: Experts haven’t set a number because normal food amounts are far below any level of concern.

What is it?

Sodium alginate thickens liquids, and it gels the moment it meets calcium. That's how the pimiento strips stuffed into olives are made, and how chefs form the "caviar" beads of molecular gastronomy.

Where it comes from: Extracted from brown seaweeds such as kelp, then purified into a powder.

Why it’s in food

Shapes pimiento filling for stuffed olives
Thickens ice cream, dressings and sauces
Forms popping boba and fruit "caviar"
Binds restructured foods such as onion rings

Often found in

Stuffed olivesIce creamSalad dressingsPopping bobaPie fillingsReflux medicine

Also listed as: Sodium alginate, Alginate, Algin, Alginic acid sodium salt, Sodium polymannuronate

Health & gut impact

Safety reviewBenefit

EFSA found no safety concern and no need for a daily limit.

EFSA Panel on Food Additives (2017)

RefluxBenefit

Alginate forms a raft on top of stomach contents, which is how alginate reflux medicines work.

Leiman et al., Dis. Esophagus (2017)

What can I use instead?

Agar-agar

Ratio: To recipe

Best for: Gels and jellies

Xanthan gum

Ratio: About 1:1

Best for: Thickening dressings

More thickeners & gums:

Agar-Agar E406Agar-agar (E406) is a seaweed gel that sets firmer than gelatin. It's safe, vegan, gluten-free, keto and kosher, and is the easiest plant swap for gelatin.Generally safe Carrageenan E407Carrageenan (E407) is a seaweed thickener in plant milks and deli meats. It's approved, but some studies link it to gut inflammation, so people with IBD often avoid it.Use in moderation Cellulose Gum (CMC) E466Cellulose gum (E466, CMC) is a thickener made from wood or cotton fiber. It's approved everywhere and fine for most diets, but studies in mice and a small human trial suggest it can disturb gut bacteria.Use in moderation GelatinGelatin is made from pig, cow or fish parts, so it is never vegan. It's only halal or kosher when certified, because most unlabeled gelatin comes from pork.Generally safe

Common questions

Is Sodium alginate safe?

Generally safe (93/100). Approved everywhere with no daily limit. EFSA re-checked the alginates in 2017 and found no safety concern.

Is Sodium alginate vegan?

Yes. Made from seaweed.

Is Sodium alginate gluten-free?

Yes.

How is the red filling in stuffed olives made?

Pimiento paste is mixed with sodium alginate, set into strips in a calcium bath, then cut and stuffed into the olives.

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Scientific sources & regulatory citations

21 CFR 184.1724 (US FDA)
EFSA OpenFoodTox: E401
EFSA Panel on Food Additives (2017)
Leiman et al., Dis. Esophagus (2017)

Last checked against FDA, EFSA and Health Canada records: November 1, 2026 · INS 401 · CAS 9005-38-3