Preservatives
Potassium benzoate
Definition
What it is
Benzoate preservative: linked to hyperactivity in children; reacts with vitamin C (ascorbic acid) to form benzene, a known carcinogen, in soft drinks.
On the label
How it appears on labels
- potassium benzoate
Regulation
Regulatory status
No bans or restrictions are recorded for this ingredient in the jurisdictions clearlabel tracks (US, EU, UK, Canada, Japan, Australia/NZ, Brazil).
Explainer
In plain language
Potassium benzoate is a preservative that stops the growth of mold, yeast, and some bacteria, especially in acidic foods and drinks. It is the potassium form of benzoic acid and does the same job as sodium benzoate. It is produced synthetically and used in small amounts to extend shelf life.
Assessment
Why it is flagged
There are two separate concerns. First, benzoate preservatives were part of the additive mixtures in the 2007 Southampton study published in The Lancet, which associated combinations of dyes and a benzoate preservative with increased hyperactivity in some children. Second, when benzoates are present alongside vitamin C (ascorbic acid) in a drink, the two can react under heat and light to form small amounts of benzene, which is classified as a carcinogen. The FDA studied benzene in soft drinks and worked with manufacturers to reformulate products where levels were a concern. Levels found were generally low, and this reaction depends on specific conditions rather than happening in every product. Clear Label flags potassium benzoate at medium severity so the dye-and-preservative combination and the vitamin C interaction are both visible and testable.
In the aisle
Where it commonly shows up
- Sodas and fruit-flavored drinks
- Bottled juices and juice blends
- Salad dressings and condiments
- Pickles and other acidic preserved foods
- Some syrups and fountain drink mixes
Practical
Reading the label
Potassium benzoate is listed by name on US labels and can appear as E212 in the EU. The benzene concern is highest when a drink lists both a benzoate and vitamin C or ascorbic acid, so scanning for that pairing is the useful check.
Alternatives
If you want to avoid it
Some people who want to avoid it choose drinks preserved by refrigeration or pasteurization instead, or products with shorter ingredient lists. Checking whether a beverage lists both a benzoate and added vitamin C can help spot the specific combination that raises the benzene question.
FAQ
Common questions
Does potassium benzoate really form benzene?
It can, but only under certain conditions. When a benzoate sits alongside vitamin C in a drink and is exposed to heat or light, small amounts of benzene can form. The FDA investigated this in soft drinks and worked with manufacturers to reformulate the products where levels were a concern.
Is it linked to hyperactivity in children?
A benzoate preservative was part of the additive mixtures in the 2007 Southampton study, which associated those mixtures with increased hyperactivity in some children. The dyes and the preservative were tested together, so the effect of the benzoate alone is hard to separate.
Is potassium benzoate the same as sodium benzoate?
They are closely related preservatives that work the same way, differing only in whether they carry potassium or sodium. The vitamin C and benzene question applies to both.
Citations
Sources
Citation
Primary reference
About this page: the definition, label names, severity, and regulatory chips come from the clearlabel ingredient taxonomy, the same data the scanner uses to score products. Research summaries describe associations reported in published studies, not diagnoses; individual responses vary. Scan any product with clearlabel to see which of its ingredients carry flags.