Boric Acid
The short version
A traditional preservative restricted to caviar in the modern EU food code.
It's permitted and generally considered safe, but there are a few reasons to be mindful — like sensitivities in some people, debated studies, or intake limits. The Safety section below explains the specifics.
Where it comes from
Crystalline boron compound derived from boron-mineral ores (borax, ulexite). Used as a preservative for fish and meat from the 19th century through the early 20th, before more selective agents became available.
How it's used
In modern EU regulation, permitted only for sturgeon caviar at up to 4 g/kg as boric acid. Broader food use has been withdrawn for decades. Still encountered as a historic ingredient in some traditionally cured products.
Safety profile
ADI of 0–0.16 mg/kg body weight (as boron, JECFA). Accumulates in tissues with chronic exposure; classified as reprotoxic at higher doses. The narrow EU permission reflects the unique storage challenges of caviar combined with very small per-capita consumption.
Physical & chemical properties
White crystalline powder or flakes, moderately soluble in water (more soluble in hot water). Weakly acidic. Heat-stable but loses water progressively on heating.
Regulation worldwide
Permitted in the EU only for caviar. Banned for general food use in most jurisdictions, including the US.
Educational information only. Not medical or dietary advice.