E338 - Phosphoric acid
What it is and how it is used
Phosphoric acid is a clear, syrupy inorganic acid made industrially by treating phosphate rock with sulphuric acid, then purifying the result to food grade. It is one of the few strong mineral acids permitted in food, and it is the reason cola tastes sharp rather than simply sweet.
Its job is to lower pH. In soft drinks that means a tart edge that balances a heavy sugar load and, incidentally, makes the drink less hospitable to microbes. Elsewhere it acts as an acidity regulator and as a synergist for antioxidants, helping them work harder by tying up trace metals that would otherwise speed up oxidation.
Foods commonly containing it
Cola and some other dark soft drinks are by far the largest dietary source. It also turns up in processed cheese, some jams and jellies, cured and cooked meats, baking powders and a range of powdered drink mixes.
Safety summary
Phosphoric acid is authorised for use in Great Britain, listed on the FSA Register of Food Additive Authorisations in the phosphate group “E 338–341, E 343 and E 450–452”.
EFSA re-evaluated the whole phosphate group in 2019 and set, for the first time, a group acceptable daily intake of 40 mg per kg of body weight per day, expressed as phosphorus, covering E 338–341, E 343 and E 450–452 together. The Panel added two caveats worth knowing: the ADI does not apply to people with moderate to severe reduced kidney function, and estimated intakes already exceed it for infants, toddlers and children.
The practical point for a shopper: phosphate exposure is cumulative across the group, and fizzy drinks are a concentrated source. That matters more for children and for anyone with kidney disease than it does for the general adult population.
Known concerns
Frequent cola drinking has been associated in observational studies with lower bone mineral density, though the phosphoric acid itself has not been established as the cause — displaced milk intake and overall diet are confounders. EFSA's own exposure work found children exceeding the phosphate group ADI, which is the better-evidenced concern.