What is it?
Calcium alginate is a calcium salt of alginic acid, a fibre taken from brown seaweed (kelp). With calcium it forms firm gels that hold up to heat, unlike sodium alginate, which gives softer gels that dissolve more easily.
E-numbers / Thickeners & emulsifiers / E404
Calcium alginate
also: Calcium salt of alginic acid
A setting agent made from brown seaweed. It sets and thickens food, and holds formed fish and meat together.
Scan a barcode to check a food for calcium alginate. NutraSafe Pro · £6.99/month · iOS
E404
Calcium alginate
Calcium alginate is a calcium salt of alginic acid, a fibre taken from brown seaweed (kelp).
VeganVegetarian
100
of the 43,325 UK supermarket foods we checked declare E404 in their ingredients
That is 0.2%, counted by its code or its name.
Only 1% of these labels print “E404”. Most use the name: look for “calcium alginate”.
Counted by NutraSafe from UK supermarket ingredient lists, September 2026. How we counted
How common it is in UK food, by aisle
- Fresh meat, poultry and fish48 products1.0% of 4,835
- Cakes, biscuits and desserts13 products0.4% of 3,715
- Cooked and cured meats13 products0.7% of 1,938
- Bread and bakery12 products0.3% of 3,682
What calcium alginate is, what it does and where you will see it
What does it do?
Calcium links the alginate chains into a gel. That lets it thicken and set food, hold water, stop ingredients separating and keep a texture across a range of temperatures. Makers also use it to wrap flavours in tiny capsules or to form thin edible coats.
Where you will see it
Formed or reshaped fish and meat, such as formed fish fillets and sliced meats, tinned and jarred fruit and vegetables, coats on fresh-cut produce, bakery fillings, dairy desserts and some processed cheese. Labels call it calcium alginate or E404.
What the science says
The body does not digest it
Alginates are a fibre that people lack the enzymes to digest. Calcium alginate passes mostly untouched through the small intestine, and gut bacteria ferment it only to a limited degree in the large bowel. Very little reaches the blood.
European reviewers concluded that alginic acid and its salts (E400 to E404), calcium alginate included, are not absorbed from the gut to any meaningful extent at the levels used in food.
2017Regulator reviewEFSA Panel on Food Additives and Nutrient Sources added to Food (ANS), EFSA Journal
No daily limit set, even for children
Regulators set no numerical daily limit, because the studies did not point to any level of concern. European reviewers' estimates of what people eat found nothing to flag for any age group, children included.
No numerical daily limit was set for E400 to E404, and reviewers raised no safety issue at the estimated intakes from food.
2017Regulator reviewEFSA ANS Panel re-evaluation of alginic acid and its sodium, potassium, ammonium and calcium salts (E 400 to E 404), EFSA Journal 15(11):5049
At very high doses in rats it binds calcium, like any fibre
Feeding studies in rodents at high doses did not produce organ damage or cancer, and it did not damage DNA in standard tests. The effects seen at very high doses came from the fibre binding minerals, not from any chemical toxicity.
Medium and long-term rodent studies found no harm from alginate at up to about 5% of the diet, apart from less calcium being absorbed at very high doses, linked to the fibre binding it.
2017Animal studyEFSA ANS Panel re-evaluation of alginic acid and its sodium, potassium, ammonium and calcium salts (E 400 to E 404), EFSA Journal
Where it stands with the regulators
Approved in the UK and the EU
Daily limit. None set.
- Legal basis
- On the Food Standards Agency's approved list for Great Britain
- Permitted foods
- Processed fruit and vegetables · Formed meat and fish · Bakery fillings and toppings · Dairy desserts and processed cheese · Tinned and jarred fruit and vegetables · Edible coats on fresh-cut produce · Many other foods, at no more than is needed
- Maximum levels
- No set maximum in most foods. Some have set limits, such as 500mg per kg in cereal-based baby foods and 10,000mg per kg in fruit and vegetable spreads.
- History
- Alginates were among the first thickeners approved in European food law. European reviewers completed a full review of E400 to E404 in 2017 and kept them approved without restriction. No bans, restrictions or warning labels have been introduced.
Who should be careful
No group is advised to avoid it on current evidence. People on very low-calcium diets should know that alginate fibre can bind calcium in the gut at high intakes, though not at normal food levels. Look for calcium alginate or E404 on the label.
The honest read
Calcium alginate is a seaweed thickener that has been used in processed food for decades. There is a lot of research on alginates, and the 2017 European review of the whole family found nothing worrying at normal intakes. The main discussion has been about fibre binding minerals at very high doses in experiments, which is true of every dietary fibre.
Common questions about calcium alginate
Is E404 banned in the UK?
No. Calcium alginate is approved in the UK and EU and allowed in a wide range of foods.
Does E404 affect how minerals are absorbed?
At very high doses in experiments, alginate fibre can bind calcium and other minerals in the gut and reduce how much is absorbed. At the levels in food this is not considered significant. People on a doctor-supervised very low-calcium diet who eat a lot of alginate-thickened food may want to know.
What foods contain E404?
Formed fish and meat, tinned and jarred fruit and vegetables, bakery fillings, dairy desserts and some processed cheese. It may also coat fresh-cut produce. Look for calcium alginate or E404.
Is E404 vegan?
Yes. It comes from brown seaweed, with nothing from animals.
Sources
- EFSA ANS Panel - Re-evaluation of alginic acid and its sodium, potassium, ammonium and calcium salts (E 400-E 404) as food additives, EFSA Journal 15(11):5049
- PMC full text of the EFSA 2017 re-evaluation (E 400-E 404)
- UK Food Standards Agency - Approved additives and E numbers (E400-E499 section)
- EU Regulation (EC) No 1333/2008 on food additives (consolidated text)
Last reviewed: 20 June 2026
It's the only app that does thisUKJaneK
You Need This AppGmac2005
Best AppGK getting skinny UK App Store reviews
See this on every food you scan
NutraSafe reads the label and puts every additive into plain English, with the source, right in the app.
NutraSafe Pro · £6.99/month · iOS