Allura Red AC and colitis in mice
What it found
In mice, long-term Allura Red AC exposure worsened colitis, while intermittent exposure did not.
Early-life exposure also increased later susceptibility.
What they found
Animal and lab studies
Colitis severity
Mice continuously exposed to Allura Red AC for 12 weeks before and during DSS had worse colitis, with more weight loss, higher disease activity, and more colon damage than mice not exposed.
Intermittent exposure
Mice exposed to Allura Red AC one day per week for 12 weeks did not show worse colitis after DSS compared to unexposed mice.
Early-life exposure
Mice exposed to Allura Red AC for 4 weeks starting at 4 weeks of age, then not exposed during DSS, still had more severe colitis later.
Serotonin link
Allura Red AC increased colonic serotonin levels and the number of serotonin-producing cells. Mice lacking TPH1, needed for serotonin production, did not show worse colitis when exposed to the dye.
Gut bacteria
Germ-free mice given gut bacteria from Allura Red AC-exposed mice developed worse colitis. Allura Red AC also raised colonic serotonin in germ-free mice, showing effects without gut bacteria.
Cell studies
In human enterochromaffin cells and mouse colon cells, Allura Red AC increased serotonin release and markers of barrier disruption, especially when inflammation was present.
What the authors conclude
“Though it remains unknown whether AR has similar effects in humans, our study reveals that chronic long-term exposure to a common synthetic colorant promotes experimental colitis via colonic 5-HT in gut microbiota-dependent and -independent pathway in mice.”
Also in their conclusions
- They conclude that chronic, but not intermittent, exposure to Allura Red AC enhances colitis susceptibility in mice, with colonic serotonin as a key mediator.
- They state that future studies are necessary to identify similar effects in humans.
- They advise that population-based studies on Allura Red AC consumption by humans, including IBD patients, are necessary to see if intake is linked to later colitis.
How it was done
The authors wanted to understand how Allura Red AC, a widely used synthetic food colorant, affects intestinal inflammation, since little was known about its impact on colitis.
They gave Allura Red AC to mice in food or water at a dose based on the human acceptable daily intake, for 12 weeks or more, then triggered colitis with DSS. They also tested intermittent exposure, early-life exposure, and effects in germ-free mice and cells.
What it can’t tell you
- These are animal and cell studies. They cannot show what happens in people.
- The study used a single dose of Allura Red AC, so it cannot show whether different doses have different effects.
- The authors note that the dose used may not match the average human exposure in daily life.
Who paid
- Funding
- Funded by CIHR (from the PubMed record).
- Conflicts
- The authors declare no competing interests.
- Authors work at
- McMaster University, Canada
The paper
- Title
- Chronic exposure to synthetic food colorant Allura Red AC promotes susceptibility to experimental colitis via intestinal serotonin in mice
- Type
- Study
- Evidence
- Animals and lab studies
- Summarised from
- Full text
- Cite
- Kwon YH, Banskota S, Wang H, et al (2022). Chronic exposure to synthetic food colorant Allura Red AC promotes susceptibility to experimental colitis via intestinal serotonin in mice. Nature communications. doi:10.1038/s41467-022-35309-yFree full textPubMed 36539404DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error