E-numbers / Acidity regulators / E270
also: L-, D- and DL-lactic acid · Milk acid
An organic acid produced naturally by fermentation, added to food to regulate acidity, extend shelf life, and create the sharp tang in fermented and pickled products.
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Lactic acid is a short-chain organic acid (2-hydroxypropanoic acid) produced when bacteria ferment sugars.
Lactic acid is a short-chain organic acid (2-hydroxypropanoic acid) produced when bacteria ferment sugars. It occurs naturally in yoghurt, kefir, sauerkraut, sourdough, cheese, and many fermented vegetables. The commercial version used in food is manufactured by bacterial fermentation of glucose or lactose, then purified. It is one of the most ancient food preservation acids in human diets.
Lowers the pH of food, making the environment more acidic. Acid conditions slow or stop the growth of spoilage bacteria and pathogens, extending shelf life. In fermented dairy products, lactic acid gives the characteristic sharp or sour taste. It also acts as a chelating agent, binding trace metals that could catalyse rancidity, and is used to buffer other acidulants to maintain a stable, controlled pH in processed foods.
Yoghurt, soured cream, kefir, cottage cheese, buttermilk, sourdough bread, pickled vegetables, olives, salad dressings, mayonnaise, soft drinks, confectionery, ready meals, meat marinades, and some infant formula preparations. On a label it appears as 'lactic acid' or 'E270'.
Lactic acid is a normal metabolite in human physiology, produced continuously in muscle tissue during exercise and metabolised by the liver. The quantities consumed from food additives are small relative to the body's own production. No evidence from regulatory reviews has identified a dietary intake level from food use that causes harm in the general population.
EFSA's Panel on Food Additives and Nutrient Sources (ANS) reviewed lactic acid and found no safety concern at the intake levels arising from its use as a food additive, and set no numerical ADI.
Lactic acid is permitted in some infant formula and follow-on formula at specified levels to adjust pH. Regulatory bodies have reviewed this use and found no safety concern for healthy term infants at permitted levels. Pre-term or metabolically compromised infants have different considerations and are managed clinically, not through general food regulation.
The EFSA Panel on Dietetic Products, Nutrition and Allergies reviewed lactic acid in processed cereal-based foods and foods for infants and young children and found the additive use acceptable.
Lactic acid is the primary end-product of lacto-fermentation by lactic acid bacteria (Lactobacillus, Streptococcus, and related species). These fermentation products have been consumed for millennia and are associated with the preserved traditional foods of most cultures. The role of fermented food in gut health is an active research area; most findings relate to live cultures in foods rather than purified lactic acid as an additive.
Observational studies link habitual consumption of fermented dairy products with favourable gut microbiome diversity, though the active component is generally attributed to live cultures rather than the lactic acid itself.
No group needs to avoid lactic acid on safety grounds. People following a vegan diet should note that when lactic acid is derived from lactose-containing substrates the finished additive may not be vegan, though most commercial food-grade lactic acid is produced from plant-based glucose fermentation. Look for 'lactic acid' or 'E270' on the label and check the manufacturer's allergen/vegan statement if this matters to you.
Lactic acid is one of the most ordinary food additives in use. It is the acid that makes yoghurt sharp, sourdough sour, and pickles tangy, whether it is listed as E270 or produced in situ by live bacteria during traditional fermentation. Regulatory reviews across decades have not identified a population-level health concern at the levels present in food. Research interest in fermented foods and gut health continues, but that work focuses on live microbial cultures, not on lactic acid itself as an isolated compound.
No. Lactic acid (E270) is approved for use in the UK under the UK FSA approved-additives list and assimilated EU Regulation 1333/2008. It is one of the most widely permitted food additives.
Yes, chemically identical. In yoghurt, lactic acid bacteria convert milk sugars to lactic acid during fermentation. When E270 is listed as an additive, it is purified lactic acid added directly, rather than produced in the food during fermentation.
Yoghurt, soured cream, kefir, sourdough bread, pickled vegetables, olives, salad dressings, soft drinks, confectionery, and some ready meals. It is also used in some infant formula to adjust pH.
Usually, but not always. Most commercial lactic acid is produced by fermenting plant-based glucose, making it vegan. Some manufacturers use lactose (from dairy) as the fermentation substrate. If you follow a vegan diet, check the manufacturer's allergen or vegan statement, as the label will not distinguish between the two production routes.
Last reviewed: 20 June 2026
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