Acetic acid
The acid in vinegar, added to food to lower pH, sharpen flavour, and slow the growth of spoilage bacteria.
What is it?
Acetic acid is a simple organic acid that gives vinegar its characteristic sharp smell and taste. In food production it is made by fermenting ethanol, the same biological process that produces wine and cider vinegar. At the concentrations used in food it is chemically identical to the acid naturally present in vinegar.
What does it do?
Lowering the pH of a food with acetic acid creates an environment that inhibits the growth of bacteria, moulds, and yeasts, extending shelf life. The sourness also balances sweetness and sharpens the overall flavour profile. In bread and baked goods it can slow staling and improve crumb texture.
Where you will see it
Most commonly found in pickles, pickled vegetables, condiments, mayonnaise, salad dressings, chutneys, ketchup, brown sauce, bread, and ready-to-eat salads. It also appears in some crisps and snack seasonings where a sharp, tangy flavour is wanted. On a UK ingredient label it will appear as acetic acid or E260.
What the science says
Tooth enamel and dental erosion
Repeated exposure of tooth enamel to acidic foods and drinks, including products containing acetic acid, is a recognised contributor to dental erosion. The risk relates to frequency of exposure and contact time with teeth, not to any toxicity of acetic acid itself. Food-level exposure in a mixed diet is broadly similar to consuming vinegar-dressed salads.
Acidic food and drink is a primary dietary driver of dental erosion; acetic acid-containing products contribute to this risk when consumed frequently.
Blood sugar and metabolic effects
Several small studies have looked at whether vinegar or acetic acid slows gastric emptying and attenuates the blood glucose rise after a meal. The evidence is real but modest: the effect sizes are small, studies are short, and most use acetic acid doses above typical food-seasoning levels. It is a dietary signal worth noting, not a treatment.
Consuming vinegar before or with a meal was associated with a lower postprandial blood glucose response in people with and without type 2 diabetes in a small meta-analysis.
Acetic acid slowed gastric emptying and reduced the postprandial glycaemic index of white bread in a randomised crossover study.
Safety at food concentrations
Regulatory reviews by EFSA and its predecessor SCF found no evidence of harm at the concentrations at which acetic acid is used in food. No numerical acceptable daily intake was set because food-level exposure was considered so unremarkable. This is not a reassurance verdict; it reflects the fact that acetic acid has been a core constituent of human diets, via vinegar, for thousands of years and has been reviewed repeatedly without a concern emerging.
EFSA's Scientific Committee on Food did not establish a numerical ADI for acetic acid, judging the intake from food use to be of no toxicological concern.
Where it stands with the regulators
Who should be careful
People with severe tooth erosion or acid reflux (GORD) may want to minimise highly acidic foods generally, including vinegar-heavy condiments and pickles. There is no specific population group flagged as at risk from acetic acid used as a food additive. Look for acetic acid or E260 on the label if you are tracking acidic ingredients for dental or digestive reasons.
The honest read
Acetic acid at food concentrations is one of the most thoroughly ordinary additives in the UK food supply. It is chemically the same substance as the acid in malt vinegar, cider vinegar, or balsamic vinegar. The science here has not produced a meaningful concern at food exposure levels: regulatory bodies across multiple decades have not set a numerical safe limit because the evidence has not pointed to one being needed. The active research is in a different direction, namely whether the acid in vinegar has modest benefits for blood glucose management after meals, though that work is preliminary and the effect sizes are small.
Related additives
Common questions
Is E260 banned in the UK?
No. Acetic acid is approved for use in food in the UK under the UK FSA approved-additives list and the assimilated version of EU Regulation 1333/2008. It has not been restricted or subjected to a warning-label requirement.
Is E260 just vinegar?
Not exactly. Vinegar is a dilute solution of acetic acid (typically 4 to 8 percent) plus water and other flavour compounds. E260 refers to acetic acid itself, which is the active acidic component of all vinegars. When used as a food additive it is added in its pure or concentrated form and diluted in the product.
What foods contain E260?
Pickles, gherkins, pickled onions, mayonnaise, salad dressings, ketchup, brown sauce, chutney, some breads, ready-to-eat salads, and certain crisps and snack seasonings. It can also appear in processed fish and seafood products.
Is E260 vegan?
Yes. Acetic acid is produced by microbial fermentation of carbohydrates or ethanol and contains no animal-derived ingredients.
Sources
- UK FSA Approved Additives and E Numbers
- EU Regulation 1333/2008 on food additives (Annex II)
- Ostman E et al., Vinegar supplementation lowers glucose and insulin responses and increases satiety after a bread meal, European Journal of Clinical Nutrition, 2005
- Johnston CS, Gaas CA, Vinegar: medicinal uses and antiglycemic effect, Medscape General Medicine, 2006
- NHS: Dental erosion causes
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