BHA and BHT (E320-E321): synthetic antioxidants with an uncertain toxicological profile

BHA and BHT have a simple function: they slow down fat oxidation. Without antioxidants, some oils, snacks, cereals, chewing gums and packaged foods become rancid more easily. The problem is that “useful” and “irrelevant” are not the same word.

The additives are E320, butylated hydroxyanisole, and E321, butylated hydroxytoluene. They often appear near the end of the ingredient list, exactly where people stop reading.

Why they are used

Fats react with oxygen, light and heat. That reaction changes smell, flavour and product stability. BHA and BHT slow that process. For food manufacturers, they mean longer shelf life and less waste.

This explains why they are authorised. It does not automatically prove cumulative exposure is irrelevant for everyone. Regulation works on that margin: maximum permitted levels, authorised foods and acceptable daily intake.

What EFSA and IARC say

EFSA re-evaluated BHA in 2011 and BHT in 2012. For BHA, it set an ADI of 1 mg/kg body weight per day. For BHT, it set an ADI of 0.25 mg/kg per day. The numbers differ because the toxicological dossiers are not identical.

IARC classified BHA in Group 2B, “possibly carcinogenic to humans”, based on experimental evidence. That classification concerns hazard. It does not say every dietary exposure causes cancer. But it also makes the opposite idea weak: “it is authorised, so it is not worth reading”.

Where the grey zone sits

Animal studies on BHA and BHT use doses and conditions that do not equal a normal diet. Some signals concern liver, thyroid, development or endocrine effects in experimental models. Turning them into a human verdict would be wrong.

The stronger point is different: these additives are not essential nutrients. They are technological tools. If they appear often in high-frequency products, their role in the diet becomes a legitimate question.

How to read the label

Look for “BHA”, “BHT”, “E320” or “E321”. They are more likely in fatty snacks, chewing gum, packaged cereals, crisps, instant mixes, flavoured oils and long-shelf-life products.

1. Check repetition: one product occasionally is different from several E320/E321 products in the same day.
2. For children, the margin per kilogram is narrower, so frequency and portion size matter.
3. Compare alternatives using other antioxidants, such as tocopherols, ascorbic acid or shorter shelf-life packaging.

Conclusion

BHA and BHT are not the centre of the diet, but they are a useful test of label reading. They preserve products; they have regulatory thresholds; one has an IARC classification that should not be inflated or ignored.

The practical choice is frequency. If E320 or E321 appears rarely, the issue remains marginal. If they appear often in daily snacks, the label is giving you useful information.

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Cited sources

• IARC Monographs, Butylated hydroxyanisole (BHA), Group 2B classification, 1986.
• National Toxicology Program, Report on Carcinogens entry for BHA.
• EFSA ANS Panel, re-evaluation of butylated hydroxyanisole (BHA, E320), EFSA Journal, 2011.
• EFSA ANS Panel, re-evaluation of butylated hydroxytoluene (BHT, E321), EFSA Journal, 2012.
• Jeong S.H. et al., reproductive/endocrine effects of BHA in rats, Toxicology, 2005.