E-numbers / Acidity regulators / E365
also: Sodium salt of fumaric acid · Monosodium / disodium fumarate
The sodium salt of fumaric acid. Not currently permitted as a food additive in the UK or EU, so it should not appear in UK food ingredients lists. It is, however, permitted in the United States under 21 CFR 172.350 and listed in the Codex Alimentarius General Standard for Food Additives (INS 366).
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This is not on the UK list of approved food additives, so you will not normally see this E number on a UK label.
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 fumarate is the monosodium or disodium salt of fumaric acid (E297), a naturally occurring organic acid found in many plants and fungi. It is a white crystalline powder. Fumaric acid itself is approved as a food additive (E297), but the sodium salt form designated E365 has not been authorised for use in UK or EU food under current legislation. Outside the UK and EU, sodium fumarate is permitted in some jurisdictions, including the United States.
As an acidity regulator it would theoretically buffer and stabilise the pH of food products, lending mild acidity or tartness. Fumaric acid salts can also act as leavening agents in baked goods. Because E365 is not authorised in UK or EU food law, it has no defined permitted function in food sold here.
E365 should not appear on any UK or EU food label, as it is not an approved additive here. Fumaric acid itself (E297) is used in some baking mixes, confectionery, and soft drinks. If you do see 'E365' or 'sodium fumarate' on a UK label, that product may be non-compliant. Look for 'sodium fumarate' or 'E365' to identify it.
Fumarate is a naturally occurring intermediate in the Krebs cycle, the energy-producing pathway found in all human cells. The body generates and processes fumarate continuously as part of normal metabolism. This metabolic familiarity is the basis for the low concern profile of fumaric acid and its salts at typical food-exposure levels.
Fumaric acid (E297) was evaluated by EFSA's Panel on Food Additives and Nutrient Sources (ANS), which noted fumarate is an endogenous metabolite and found no safety concern at the reported uses.
Unlike fumaric acid (E297), sodium fumarate (E365) does not appear in Annex II of assimilated EU Regulation 1333/2008, the list that defines which additives may legally be used in UK and EU food. The E-number range in the legislation skips from E363 (succinic acid) to E380 (triammonium citrate) with no fumarate salt entries in between. An E-number designation does not itself confer authorisation; inclusion in Annex II is required for lawful use.
E365 sodium fumarate does not appear in Annex II of UK assimilated Regulation (EC) No 1333/2008 (version in force as of June 2024). Only fumaric acid (E297) is listed among permitted fumarate-related additives.
Sodium fumarate is permitted as a food additive in the United States under 21 CFR 172.350, which explicitly names fumaric acid and its calcium, ferrous, magnesium, potassium, and sodium salts as safe for direct addition to food. The Codex Alimentarius General Standard for Food Additives also lists sodium fumarates at INS number 366 as an acidity regulator. This demonstrates that the UK/EU non-authorisation reflects a regulatory gap rather than a global ban or identified safety concern.
21 CFR 172.350 states that fumaric acid and its calcium, ferrous, magnesium, potassium, and sodium salts may be safely used in food for human consumption.
Sodium fumarates are listed in the Codex Alimentarius General Standard for Food Additives (GSFA, Codex STAN 192-1995) under INS number 366 as an acidity regulator.
Because E365 is not permitted in UK food, encountering it on a label is itself a red flag. Anyone avoiding sodium (for blood pressure management) should also be aware that sodium fumarate contributes to dietary sodium if consumed, but given its non-permitted status, this is largely theoretical for UK shoppers.
E365 sits in an unusual position: it has an E-number in reference databases but no legal authorisation to be used in UK or EU food products. The underlying fumarate chemistry is wholly unremarkable from a health standpoint since fumarate is a substance every human body produces continuously. Notably, sodium fumarate is permitted as a food additive in the United States and is listed in international Codex standards, so the UK/EU non-authorisation is a regulatory gap rather than a reflection of identified harm. The practical point for a UK shopper is straightforward: this additive should not be on any UK food label, and seeing it there would be a labelling or compliance issue.
E365 (sodium fumarate) is not listed as a permitted food additive in the UK under assimilated EU Regulation 1333/2008. It is not approved for use in UK food, meaning its presence in an ingredient list would represent a compliance problem. This is different from a specific ban; it simply has no authorisation. In contrast, sodium fumarate is permitted in the United States under 21 CFR 172.350.
E-numbers are designations used in reference lists and databases for substances that have been reviewed or assigned a number, but having an E-number does not automatically mean a substance is authorised for use in food. Authorisation requires inclusion in Annex II of the food additives regulation, which E365 does not have in the UK or EU.
No UK or EU foods should legally contain E365 sodium fumarate, as it is not an approved additive here. Fumaric acid (E297), a related compound, is permitted and found in some baking mixes, confectionery, and beverages. Sodium fumarate may appear in foods produced in countries where it is permitted, such as the United States.
Sodium fumarate is a synthetic inorganic salt with no animal-derived components, so it would be considered vegan. However, as it is not an authorised food additive in the UK, this question is largely academic for UK food shoppers.
Last reviewed: 20 June 2026
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