Sodium Tetraborate (Borax)
The short version
A borate salt permitted essentially only to preserve and firm sturgeon caviar; restricted elsewhere.
It's allowed, but comes with clearer cautions — such as reactions in sensitive people, stricter limits, or contested safety. The Safety section below explains why.
Where it comes from
A boron mineral salt (borax), refined from borate ores. Far better known as a cleaning and laundry agent.
How it's used
In food it is permitted essentially only as a preservative for sturgeon caviar, where it firms the eggs and extends shelf life.
Safety profile
Borates are restricted because they accumulate in the body and can affect fertility and development at higher doses; the caviar use is a narrow low-level exception. Not permitted as a general food additive in most countries.
Physical & chemical properties
White crystalline powder, water-soluble, mildly alkaline.
Regulation worldwide
EU — permitted only for caviar (with E284); banned as a general food additive in the US and most countries.
Educational information only. Not medical or dietary advice.