E-numbers / Antioxidants / E315
also: Isoascorbic acid · D-araboascorbic acid · erythorbate
A synthetic antioxidant derived from sugar, used to stop fats going rancid and to hold the pink-red colour of cured meat.
Scan a barcode to check a food for erythorbic acid. NutraSafe Pro · £6.99/month · iOS
Sturgeon Caviar (Fish) 96,5%, Salt, Preservative (E200), Antioxidants (E300 and E315)
EFSA found low acute toxicity, no adverse effects in available studies and no genotoxicity or carcinogenicity concern, identified a no-effect level of 650 mg/kg a day, and retained the acceptable daily intake of 6 mg/kg a day.
Why it’s worth knowing. EFSA found low acute toxicity, no adverse effects in available studies and no genotoxicity or carcinogenicity concern, identified a no-effect level of 650 mg/kg a day, and retained the acceptable daily intake of 6 mg/kg a day.
Erythorbic acid (also called isoascorbic acid or D-isoascorbic acid) is a synthetic antioxidant produced by fermentation of glucose. It is a structural isomer of ascorbic acid (vitamin C, E300) but shares almost none of its vitamin activity, providing less than 5% of the biological vitamin C effect. It is not found naturally in food in meaningful quantities.
It scavenges oxygen and free radicals, slowing oxidative reactions that turn fats rancid and cause colour changes. In cured meats it also accelerates the reaction between added nitrite and myoglobin, speeding up formation of the stable pink-red pigment (nitrosomyoglobin) and reducing residual free nitrite. In fruit juices and fish it prevents enzymatic and non-enzymatic browning.
Most commonly found in cured and processed meats such as bacon, ham, cooked sausages, frankfurters, pate, and corned beef. Also used in frozen fish and seafood, some canned vegetables, and fruit juices. On a UK ingredient label it appears as 'erythorbic acid' or 'antioxidant (E315)'.
Despite its chemical resemblance to vitamin C, erythorbic acid has very little vitamin C bioactivity in the human body. Studies show it cannot meaningfully substitute for ascorbic acid in preventing scurvy or supporting collagen synthesis. It is metabolised differently and excreted more rapidly. Manufacturers chose it over vitamin C partly because it is cheaper to produce and performs well as an antioxidant without the added vitamin benefit.
Erythorbic acid has approximately 1/20th to 1/5th the vitamin C activity of ascorbic acid in standard bioassay models, meaning it cannot replace dietary vitamin C.
There is a theoretical concern that high intake of erythorbic acid may increase urinary oxalate excretion, because it can be metabolised to oxalic acid. For most people this is unlikely to be relevant at the amounts encountered in food. Individuals with a history of calcium oxalate kidney stones are sometimes advised to moderate intake of oxalate-generating compounds, though no specific guidance names erythorbic acid as a primary concern.
Like ascorbic acid, high-dose erythorbic acid can generate oxalate as a metabolic by-product, which is a recognised risk factor for calcium oxalate urolithiasis in susceptible individuals.
In cured meats, erythorbic acid is added alongside sodium nitrite. It speeds up conversion of nitrite to the stable colour pigment, which incidentally reduces residual free nitrite in the final product. Whether this meaningfully alters the formation of nitrosamines, which are associated with increased bowel cancer risk, is debated. The relevant concern for regular cured-meat eating relates to the nitrite system overall rather than to erythorbic acid specifically.
Erythorbic acid accelerates the formation of nitrosomyoglobin from nitrite in cured meat, reducing residual nitrite levels in the final product.
Processed meat consumption is classified as IARC Group 1 (causes colorectal cancer in humans), primarily attributed to the nitrite/nitrosamine chemistry in cured products, not to the antioxidants added alongside.
People with a history of calcium oxalate kidney stones may wish to be aware of erythorbic acid as one of several oxalate-generating compounds in processed foods, though it is not singled out by UK clinical guidance. Look for 'erythorbic acid' or 'E315' in the ingredients list.
Erythorbic acid is a well-characterised additive that has been in use since the 1950s. The science around it is settled in one sense: it works as an antioxidant, it is not vitamin C in any practical sense, and at food-level doses the kidney stone signal is theoretical rather than demonstrated. The more substantive question for regular eaters of cured meat is the nitrite chemistry that erythorbic acid supports, and that is where the IARC Group 1 designation for processed meat sits. Erythorbic acid itself is not the concern; the company it keeps in bacon and ham is.
No. E315 is approved for use in the UK as an antioxidant under the UK FSA approved-additives list and the UK's retained version of EU Regulation 1333/2008.
No. Erythorbic acid has a very similar chemical structure to vitamin C (ascorbic acid, E300) but it has almost no vitamin C activity in the body and cannot be used as a substitute for dietary vitamin C.
E315 is most commonly found in cured and processed meats including bacon, ham, frankfurters, cooked sausages and pate. It also appears in some frozen fish, canned fish, and fruit juices.
Yes. Erythorbic acid is produced by fermentation of glucose (a sugar), with no animal-derived ingredients involved in its manufacture.
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
NutraSafe reads the label and puts every additive into plain English, with the source, right in the app.
NutraSafe Pro · £6.99/month · iOS
