E-numbers / Other additives / E550
also: Sodium silicate · Sodium metasilicate · Water glass
A group of sodium and silicon compounds. Not currently authorised as a food additive in the UK or EU; used industrially in water treatment and detergents.
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Wheat Flour, Vegetable Oils (Palm, Canola), Antioxidant (E306), Brown Sugar, Sugar, Mixed Grain Powder (Barley, Brown Rice, Soybean, Black Rice), Maple Syrup, Cinnamon, Salt, Raising Agents (E550(i), E503(ii)), Flavouring
This is not on the UK list of approved food additives, so you will not normally see this E number on a UK label.
1
of the 43,325 UK supermarket foods we checked declare E550 in their ingredients
That is under 0.1%, counted by its code or its name.
Counted by NutraSafe from UK supermarket ingredient lists, September 2026. How we counted
Why it’s worth knowing. This is not on the UK list of approved food additives, so you will not normally see this E number on a UK label.
Sodium silicates are inorganic compounds formed from sodium oxide and silicon dioxide. The group includes sodium metasilicate (E550i) and sodium sesquisilicate (E550ii). They are white or colourless solids or thick liquids, often called water glass in liquid form. They are chemically related to other silicate additives such as silicon dioxide (E551) and the aluminium silicates (E554-E559), but sodium silicates themselves are not authorised food additives in the UK or EU.
In industrial and non-food contexts, sodium silicates act as binders, sealants, corrosion inhibitors, and dispersing agents. They have alkaline, antimicrobial, and desiccant properties. In the food-contact and water-treatment sectors, they are used to coat the inside of water pipes to reduce leaching of metals. They are not used as direct food additives in the UK or EU.
Sodium silicates are not permitted direct food additives in the UK or EU, so they do not appear on food ingredient labels in those markets. They may appear in industrial cleaning products, cement, detergents, water treatment chemicals, and paper coatings. Some older food-science literature discusses potential anticaking or antimicrobial uses, but these are not reflected in current authorised lists.
The UK FSA approved-additives register does not include E550 among permitted food additives. The adjacent codes E551 (silicon dioxide) and E554 (sodium aluminium silicate) are authorised anticaking agents; E550 is not. The EU's Regulation 1333/2008 Annex II, which governs permitted food additives in the EU and is retained in UK law, does not list sodium silicates as a permitted food additive for any food category. The UK Statutory Instrument UKSI 2024/685, which amended food additive authorisations in England, makes no mention of sodium silicates and did not add E550 to any permitted list. The FSA's Authorised Regulated Food and Feed Products register (data.food.gov.uk) has no entry for E550, confirming it is absent from the current Great Britain authorised-additives register.
E551 (silicon dioxide) and E554 (sodium aluminium silicate) appear in the UK FSA approved-additives list as anticaking agents; E550 (sodium silicates) does not appear in that list.
EU Regulation 1333/2008 Annex II lists permitted food additives and their conditions of use; sodium silicates (E550) are not included among the authorised silicate anticaking agents.
The Food Additives and Novel Foods (Authorisations and Miscellaneous Amendments) and Food Flavourings (Removal of Authorisations) (England) Regulations 2024 (UKSI 2024/685) does not mention sodium silicates or E550 and did not add this substance to any permitted food additive list.
Sodium silicates are strongly alkaline at higher concentrations and are classified as irritants to skin, eyes, and the respiratory tract in occupational and industrial contexts. These properties are relevant to workers handling them industrially, not to consumers via food, since they are not used as direct food additives.
Sodium metasilicate solutions are corrosive to skin and mucous membranes at concentrations used industrially; industrial safety datasheets classify them as irritants or corrosives depending on concentration.
It is easy to confuse sodium silicates (E550) with the adjacent permitted additives: silicon dioxide (E551) is a widely used anticaking agent in powdered foods; calcium silicate (E552), magnesium silicate (E553), and sodium aluminium silicate (E554) are also authorised anticaking agents. Sodium silicates have a different chemistry and regulatory history, and the absence of E550 from the authorised list means any food label showing E550 in the UK or EU would indicate a compliance issue.
EFSA has conducted re-evaluations of silicate food additives including E551, E552, E553, E554, and E555; no parallel re-evaluation or authorisation exists for E550 in the published EFSA opinions list.
Because E550 is not a permitted direct food additive in the UK or EU, no one should encounter it on a food label under normal circumstances. If E550 appears on a product label, the product may be non-compliant with UK or EU food additive law.
This is a case where the E-number designation exists in secondary databases and older food-additive catalogues, but sodium silicates are not on the current UK or EU permitted food additive lists. The compounds are well established in industrial chemistry and water treatment, and they are not novel or mysterious. The absence from the approved list is not because they were banned after a safety scare, but because they were never brought through the authorisation process as a direct food additive. A shopper is very unlikely to see E550 on any food bought in the UK.
E550 is not on the UK FSA approved-additives list, meaning it is not authorised for use as a direct food additive. It was not removed after a ban; it was never authorised as a food additive in the UK or EU. Sodium silicates are used industrially and in water treatment under separate legislation.
Yes. Sodium silicates are approved under water-treatment and drinking-water regulations for lining pipes to reduce metal leaching. That is a different legal framework from food additive law, which governs what can be added directly to food products.
No foods sold legally in the UK or EU should contain E550 as a direct additive, because it is not on the authorised list. If you see E550 on a UK food label, that would be unusual and worth reporting to the Food Standards Agency.
Sodium silicates are inorganic mineral compounds with no animal-derived components, so they would be vegan. However, as E550 is not a permitted food additive in the UK or EU, the question of its dietary status is largely academic for shoppers in these markets.
Last reviewed: 20 June 2026
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