TBHQ (tert-butylhydroquinone)

What you need to know

TBHQ is a synthetic antioxidant that stops frying oils and instant-noodle oils going rancid.

It is approved everywhere with strict limits, but it attracts research attention: very high doses in animals affected the stomach lining, and some early studies have asked questions about immune effects. None of this is established at food levels.

Products that switch away from it usually use vitamin E (tocopherols) instead.

Where it stands, by region

The same additive can be approved in one country and banned in another. This is the divergence that matters most.

🇦🇺AU / NZ	Approved Permitted in oils and fried products with maximum levels (FSANZ).
🇪🇺EU	Approved Permitted with maximum levels; ADI 0.7 mg/kg bw/day.
🇺🇸US	Approved Permitted (FDA).
🇨🇦CA	Approved Permitted (Health Canada).

Health evidence

How settled the science is for each area — not how dangerous. “Unknown” means not enough good studies yet.

Hyperactivity & behaviour

Unknown

Allergy & intolerance

Unknown

Gut microbiome

Unknown

Metabolic effects

Suspected

Carcinogenicity

High-dose animal evidence only

Suspected

Cardiovascular

Unknown

tert-Butylhydroquinone, a fat-soluble phenolic antioxidant. ADI 0.7 mg/kg bw/day (JECFA; EFSA 2004 concurred).

Synthesis: SyntheticADI 0.7 mg/kg bw/day