Allura Red
A synthetic red azo dye made from petroleum, used to colour food and drinks. One of the six colours required by UK law to carry a hyperactivity warning.
Linked to increased hyperactivity in children of the general population, not just those with ADHD. Animal research suggests chronic intake may disrupt gut serotonin and increase susceptibility to bowel inflammation. High intake in young children can exceed the acceptable daily limit.
What is it?
Allura Red AC is a dark-red, water-soluble synthetic azo dye. It is produced from petroleum-derived compounds and belongs to the azo dye class, meaning it contains a nitrogen-nitrogen double bond that gives it its colour. It is also known as FD&C Red No. 40 in the United States and carries the E number E129 in the UK and EU.
What does it do?
It works purely as a colour, absorbing light at around 504 nanometres to produce a bright red-to-orange-red hue. It has no flavour, preservative or nutritional function. It is highly stable under light, heat and pH changes, making it reliable for manufactured foods.
Where you will see it
Found in red-coloured sweets, chewing gum, fruit-flavoured drinks and squashes, some sports drinks, flavoured crisps, cereal bars, glacé cherries, jelly, some cakes and biscuits, and certain ice creams. It is widely used in fizzy drinks, particularly those with berry, cherry or strawberry flavourings. On a UK label it appears as Allura Red AC or E129.
What the science says
Hyperactivity in children
A randomised, double-blinded, placebo-controlled trial from the University of Southampton, published in The Lancet in 2007, tested mixtures of six artificial colours including E129 combined with sodium benzoate in children aged three and eight or nine. Children given the colour mixes showed statistically significant increases in hyperactive behaviour compared with those given placebo drinks. The effect was seen across the general population, not only in children already diagnosed with ADHD. Because the study tested mixtures rather than individual dyes, it is not possible to say how much, if any, of the effect was caused by E129 alone.
Mixtures containing E129 and five other synthetic colours plus sodium benzoate significantly increased hyperactive behaviour in three-year-olds and eight or nine-year-olds from the general population in a randomised controlled trial.
EFSA concluded the Southampton study provided some evidence of an effect on activity and attention in children, though the size of the effect was modest and the study design could not isolate individual dyes.
Gut inflammation in animal studies
A 2022 study published in Nature Communications by researchers at McMaster University found that chronic exposure to Allura Red AC in mice increased colonic serotonin levels, impaired gut barrier function, and raised susceptibility to experimental colitis. The effect depended on continuous exposure; intermittent exposure did not produce the same result. The study was conducted in mice using experimental models of IBD, and the authors stated that whether the findings apply to humans is unknown. No human trial has yet tested this mechanism.
Chronic but not intermittent exposure to Allura Red AC promoted susceptibility to experimental colitis in mice via elevated intestinal serotonin and impaired epithelial barrier function.
Genotoxicity and carcinogenicity
Multiple studies and EFSA's 2009 re-evaluation concluded that Allura Red AC is not genotoxic in standard in vitro and in vivo tests, including the Salmonella reverse mutation assay and heritable translocation tests in mice. Long-term carcinogenicity studies in rats and mice at very high doses were negative. However, a 2024 narrative review in the journal Carcinogenesis noted that its breakdown products may have DNA-damaging potential via gut bacterial metabolism, and called for dedicated carcinogenicity studies. No governing agency currently classifies E129 as a carcinogen.
Allura Red AC was negative in standard genotoxicity tests in vitro and in vivo, and negative in long-term carcinogenicity studies in rats and mice.
A 2024 review concluded that while no agency classifies Allura Red AC as a carcinogen, its interactions with inflammatory mediators, the gut microbiome, and DNA-damage pathways make it 'suspect and worthy of further molecular investigation'. Dedicated cancer-specific studies have not yet been conducted.
Exposure levels in children
In its 2009 opinion, EFSA found that children aged one to ten could exceed the acceptable daily intake of 7 milligrams per kilogram of body weight per day at high consumption levels if maximum permitted levels were used throughout. A 2015 refined EFSA assessment using actual industry usage data found that no population group exceeded the ADI under realistic scenarios. The concern about ADI exceedance is therefore most relevant to children who consume several E129-containing products simultaneously.
Under worst-case maximum permitted level scenarios, estimated intake of E129 in children aged one to ten exceeded the ADI of 7mg/kg body weight per day.
Refined exposure assessment using actual industry usage data found that no population group exceeded the ADI at mean or high (95th percentile) consumption levels.
Where it stands with the regulators
Who should be careful
Children with noticeable hyperactivity or attention difficulties may be worth monitoring, particularly if they consume several E129-containing foods and drinks in a day. Parents looking to reduce intake should check labels for 'Allura Red AC' or 'E129'. Anyone with existing inflammatory bowel conditions may wish to take note of the emerging animal research, though no human evidence yet confirms a link.
The honest read
E129 has one of the more active research profiles of any food colour currently on the UK market. The hyperactivity link in children is the most established concern: it drove a mandatory warning label across the UK and EU, and the original 2007 Lancet trial that triggered it was a proper randomised controlled study, not just an observational signal. The limitation is that the study tested a mixture of six colours plus a preservative, so it is not proven that E129 alone causes the effect. The gut inflammation findings from 2022 are striking in their mechanism, but they come from mice given continuous exposure, and the authors explicitly noted the uncertainty about human relevance. The 2024 carcinogenicity review raises further questions but stops well short of evidence of harm in humans. The picture is one of genuine, live scientific concern rather than settled danger: regulators have not restricted it beyond the warning label, but the research is not finished.
Related additives
Common questions
Is E129 banned in the UK?
No. E129 is permitted in the UK under the assimilated EU Regulation 1333/2008. However, any food or drink containing it must carry the warning 'may have an adverse effect on activity and attention in children' on the label. The FSA asked manufacturers to remove it voluntarily in 2008, and many did, but it remains legal.
What is the hyperactivity warning on E129 foods?
UK and EU law requires any product containing E129 to display the phrase 'may have an adverse effect on activity and attention in children', followed by the name or E number of the colour. This came into force in July 2010 following the 2007 University of Southampton trial published in The Lancet.
What foods contain E129?
It is most common in red or orange-coloured sweets, fruit-flavoured fizzy drinks and squashes, sports drinks, glacé cherries, jelly, certain cereals, flavoured crisps, and some biscuits and cakes. It appears on the label as Allura Red AC or E129.
Is E129 vegan?
The dye itself is synthesised from petroleum-derived compounds and contains no animal-derived ingredients. Most vegan organisations consider it vegan in terms of composition. However, animal testing has been used in its regulatory assessment, which some vegans object to on ethical grounds.
Sources
- Approved additives and E numbers - Food Standards Agency
- E129 Allura Red AC - FSA Regulated Products Database
- McCann et al. - Food additives and hyperactive behaviour in 3-year-old and 8/9-year-old children in the community: a randomised, double-blinded, placebo-controlled trial. The Lancet, Vol. 370, pp. 1560-1567
- EFSA Panel on Food Additives - Scientific Opinion on the re-evaluation of Allura Red AC (E 129) as a food additive. EFSA Journal 2009; 7(11):1327
- EFSA - Refined exposure assessment for Allura Red AC (E 129). EFSA Journal 2015; 13(10):4007
- Kwon, Banskota et al. - Chronic exposure to synthetic food colorant Allura Red AC promotes susceptibility to experimental colitis via intestinal serotonin in mice. Nature Communications, 2022
- Hofseth et al. - Allura Red AC is a xenobiotic. Is it also a carcinogen? Carcinogenesis, Vol. 45, Issue 10, p. 711, 2024
- University of Southampton - Major study indicates a link between hyperactivity in children and certain food additives (2007 press release)
- EFSA - Evaluates Southampton study on food additives and child behaviour
Aaron Keen is the founder of NutraSafe. He researches and writes every additive entry himself, from the primary sources. About the research →
This is a guide, not medical advice. If an additive affects you, speak to your GP or a dietitian.
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