E321 — BHT
E321 (BHT), a antioxidant, is rated "avoid": worth avoiding. A synthetic antioxidant, BHA's twin, in cereals, fats, chewing gum, and beer. Its evidence base is weaker than BHA's — IARC rates it Group 3 (not classifiable as to carcinogenicity). The caution rests on thyroid and reproductive effects in animal studies and the fact that it is an avoidable synthetic.
What is BHT?
A synthetic petroleum-derived antioxidant used to stop fats going rancid. You meet it in breakfast cereals, cooking fats, chewing gum, some beers, and in cosmetics and packaging. It is often used alongside BHA.
What does it do to the body?
Be clear about the strength of the evidence here: it is thinner than BHA's. IARC reviewed BHT and placed it in Group 3 — not classifiable as to carcinogenicity in humans, meaning the data don't support a cancer call either way. What EFSA did find in rat studies were thyroid effects and reproductive effects (litter size, sex ratio, pup weight gain), which is what its low daily limit is built on. The honest position: no proven harm at food levels, an unresolved endocrine question in animals, and no benefit to you personally — the additive serves shelf life, not nutrition.
What regulators say
EFSA set an acceptable daily intake of 0.25 mg per kg of body weight per day in 2012, derived from thyroid and reproductive effects in rats, and concluded intakes were below that. The FDA permits it as GRAS. IARC rates it Group 3. It is legal everywhere it is used — the flag reflects the animal endocrine findings and its status as an unnecessary synthetic, not a carcinogen classification.
Risk rating: Avoid
Known or suspected to cause harm: a substance EFSA or another regulator has flagged, or one restricted in some jurisdictions. Best kept out of a regular diet.
Source: EFSA — re-evaluation of BHT (E 321) (2012) ↗