Boric acid

Boric acid is an inorganic compound of boron used as a preservative in one highly restricted food application: the preservation of sturgeon roe (caviar). Boric acid and its salt sodium tetraborate (E285) are the only authorised methods for preserving pressed caviar within the EU, where they inhibit microbial spoilage of this luxury food product. Boric acid functions as a broad antimicrobial agent through mechanisms that include enzyme inhibition and disruption of cellular processes. Its use in food has been progressively restricted to this single niche application due to safety concerns.

JECFA evaluated boric acid in 1998 and established an ADI of 0.16 mg/kg body weight per day, expressed as boron. This conservative limit reflects the finding that boron accumulates in the body (with a half-life of approximately one week in humans) and that excessive intake is associated with reproductive and developmental toxicity in animal studies. Human populations with naturally high boron intake from drinking water and food have been studied, providing epidemiological data that inform the safe intake level. Typical boron intake from food is substantially lower than the ADI for most people.

Boric acid is approved in the EU as E284 only for use in sturgeon roe (caviar) — it is not permitted in any other food category. This highly restricted authorisation reflects both the significance of caviar as a traditional food product requiring specific preservation and the need to limit consumer boron exposure from additives. Consumers of caviar should note this restriction and be aware that the boron intake from occasional caviar consumption contributes minimally to total dietary boron exposure. For the general population who do not eat caviar, boric acid as a food additive is essentially irrelevant to dietary boron intake.