What are the harmful effects of allura red?

October 6, 2025 •

3 min read

According to a 2022 study by McMaster University researchers, continual exposure to the common food dye allura red harms gut health and promotes inflammation in experimental animal models, raising alarms about its widespread consumption.

Quick Summary

Allura Red, a common synthetic food dye derived from petroleum, is associated with a range of health concerns, including hyperactivity, intestinal inflammation, and potential genotoxicity.

Key Points

Hyperactivity Link: Studies have connected Allura Red consumption to increased hyperactivity in some sensitive children.
Gut Health Disruption: Research in animal models shows the dye can cause intestinal inflammation and dysbiosis, potentially damaging the gut barrier.
Genotoxic Potential: Although not classified as a carcinogen, Allura Red contains carcinogenic contaminants and its metabolic products can cause DNA damage in animal studies.
Allergic Reactions: Individuals may experience allergic or intolerance reactions to Allura Red, with symptoms ranging from hives and swelling to migraines.
Regulation Differences: The European Union requires a warning label on products containing Allura Red regarding potential effects on children, while the US FDA currently does not.
High Consumption Risk for Children: Because Allura Red is prevalent in products marketed to children, this population often has higher exposure and may be more vulnerable to its effects.

Understanding Allura Red (FD&C Red No. 40)

Allura Red AC, also known as Red Dye 40 or E129, is a synthetic food colorant widely used in ultra-processed foods, beverages, cosmetics, and medications to provide a red-orange color. Approved by the FDA in 1971, it is the most commonly used red dye in the United States. However, scientific evidence has linked Allura Red to potential adverse health effects concerning gut health, neurological function, and inflammation.

Potential Neurobehavioral and Psychological Effects

The potential impact of Allura Red on neurological and behavioral health, particularly in children, has been a long-standing concern. A 2007 University of Southampton study suggested a link between artificial color mixtures containing Allura Red and increased hyperactivity in children. This led the European Union to require a warning label on products with the dye: “may have an adverse effect on activity and attention in children”.

While not affecting everyone, a 2021 report from California's OEHHA associated synthetic food dyes with adverse neurobehavioral effects in children. Animal studies also indicate memory impairment and structural changes in the brain of rats exposed to Allura Red.

The Impact on Gut Health and Inflammation

Recent research highlights Allura Red's effects on the gut. It is metabolized by gut bacteria, potentially triggering chronic inflammation.

Disruption of the Microbiome and Intestinal Barrier

Studies suggest Allura Red affects the gut through several mechanisms:

Alters Microbiota: It can change the balance of gut microorganisms, leading to dysbiosis.
Increases Intestinal Serotonin: Animal studies show increased gut serotonin, potentially altering the microbiome and increasing colitis susceptibility.
Impairs Gut Barrier: Chronic exposure can make the gut barrier more permeable, allowing toxins to enter the bloodstream and contribute to inflammation.
Promotes Colonic Inflammation: In mice, chronic exposure worsens colitis and causes low-grade inflammation.

Genotoxicity and Carcinogenic Concerns

While not classified as a carcinogen by governing agencies, further investigation into Allura Red's molecular effects is warranted. There are concerns about its potential to cause DNA damage.

Contaminants and Metabolic Products

Manufacturing can introduce carcinogens like benzidine and p-cresidine, which can damage DNA.
Gut bacteria can metabolize Allura Red into products that may form DNA adducts.
Some animal studies show a link between Allura Red exposure and DNA damage in the colon.

Allergic Reactions and Intolerance

Allura Red can cause allergic or intolerance reactions in some people. True allergies are rare, but intolerance is more common.

Symptoms of Allergic or Intolerance Reactions

Skin: Hives, rashes, itching, and swelling.
Respiratory: Asthma-like symptoms.
Gastrointestinal: Nausea, vomiting, diarrhea, and abdominal cramps.
Headaches: Migraine sufferers often report sensitivity.
Behavioral: Exacerbated hyperactivity in sensitive children.

Allura Red vs. Natural Alternatives: A Comparison


Feature	Allura Red (E129)	Natural Alternatives (e.g., Beetroot, Paprika)
Origin	Synthetic, derived from petroleum distillates	Plant or mineral-based sources
Health Concerns	Linked to hyperactivity, inflammation, and potential genotoxicity	Generally considered safer, potential for allergic reactions in some cases (e.g., carmine)
Regulation	FDA approved, EU requires warning label for behavioral effects	Varies by source, some require specific labeling (e.g., cochineal)
Color Stability	Highly stable, vibrant red-orange color	May be less stable, susceptible to heat and light
Nutritional Value	None; purely aesthetic	May offer nutritional benefits, such as antioxidants
Common Use	Soft drinks, candies, cereals, baked goods, medications	Yogurts, desserts, natural snacks

Conclusion

While the FDA considers Allura Red safe at approved levels, growing evidence from animal studies and research into its long-term effects raises health concerns. Potential links to hyperactivity, gut inflammation, DNA damage, and allergic reactions, particularly in sensitive groups like children, suggest caution. Consumers can check labels for "Allura Red AC," "Red 40," or "E129" and choose naturally colored options. As research progresses, being informed is key to making dietary choices. For detailed scientific reviews, consult studies like the one in the International Journal of Occupational and Environmental Health.

Note: The content above is for informational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

Frequently Asked Questions

Allura Red AC, also known as Red Dye 40 or E129, is a synthetic, petroleum-derived food colorant widely used to give a red-orange color to many foods, drinks, and medications.

Allura Red and other synthetic food dyes do not cause ADHD, but they can worsen symptoms like hyperactivity and inattentiveness in certain sensitive children.

Symptoms can include skin reactions like hives and itching, swelling, headaches, migraines, and gastrointestinal upset such as nausea or diarrhea.

While not banned in the EU, products containing Allura Red must carry a warning label about potential effects on children. Some countries have stricter regulations or have previously banned it.

Yes, studies in animal models have found that chronic exposure to Allura Red can harm gut health by disrupting the microbiome, promoting inflammation, and impairing the intestinal barrier.

Allura Red is not officially classified as a carcinogen by governing agencies. However, it is contaminated with potentially cancer-causing substances and has been shown to cause DNA damage in some animal studies, warranting further research.

To avoid Allura Red, check product labels for ingredients listed as "Allura Red AC," "Red 40," "FD&C Red No. 40," or "E129." Choosing naturally colored alternatives is a proactive step.

Calls for further research into the long-term effects of Allura Red continue in the US. This follows the FDA's recent action to ban the related dye Red No. 3 due to cancer concerns, which highlights evolving understanding of food dye safety.