Food Dye Red 40 Triggers Inflammatory Bowel Diseases: Study

Before you decide to dive into those holiday cookies, cakes and other pastries colored with bright red dye, you might want to consider this:  Long-term consumption of FD&C Red 40 (Allura Red) food dye* can be a potential trigger of inflammatory bowel diseases (IBDs), Crohn’s disease and ulcerative colitis. Researchers using experimental animal models of IBD** found that continual exposure to the red food dye harms gut health and promotes inflammation.

This is not the first time researchers have sounded the alarm about synthetic food dyes like FD&C Red 40.  Not long ago we published a study that demonstrated a risk of colitis and IBD for some people, triggered by synthetic food dyes. Now, scientists have demonstrated that Red Dye 40 directly disrupts gut barrier function and increases the production of serotonin, a hormone/neurotransmitter found in the gut, which subsequently alters gut microbiota composition leading to increased susceptibility to colitis.


“What we have found is striking and alarming, as this common synthetic food dye is a possible dietary trigger for IBDs. This research is a significant advance in alerting the public on the potential harms of food dyes that we consume daily…

The literature suggests that the consumption of Allura Red [Red Dye 40] also affects certain allergies, immune disorders and behavioral problems in children, such as attention deficit hyperactivity disorder.”

-Dr. Waliul Khan, Professor, Department of Pathology and Molecular Medicine, McMaster University, and principal investigator of Farncombe Family Digestive Health Research Institute (source)

food chemicals-red dye 40 processed foods

* In the U.S., the synthetic food dye FD&C Red 40 is commonly used in processed foods. See the book excerpt below for a list of places FD&C Red 40 food dye is hiding.



“The Food Hacker’s Handbook: A Guide to Breaking the Processed Foods and Additives Addiction”

“FD&C Red Dye #40 contains a known carcinogenic contaminant (aniline) and has been linked in animal studies to intrauterine developmental problems, behavioral and physical toxicity, genotoxicity, and colon DNA damage.  Red Dye 40 has been linked in clinical trials with allergy-like hypersensitivity in a small number of adults (including skin reactions such as itching and hives, swelling/edema, digestion problems, earaches, swollen lymph nodes, agitation, nervousness, and migraine headaches) and as a potential trigger for hyperactivity in children.  This widely used food dye makes an appearance in numerous processed foods including breakfast cereals and toaster pastries, candies, dairy products, chocolate, pudding mix, cake mixes, snack chips, desserts, bakery goods (including refrigerated and frozen dinner rolls), processed drinks such as orange soda and other flavored sodas and drink mixes marketed to children¹.  It may also be present in over the counter and prescription drugs, as well as pet food.” ©

¹A 2014 report released by the FDA estimates that at least 96 percent of children aged 2-5 years are exposed to synthetic food dye Red 40, as well as food dyes Yellow 5 (tartrazine), Yellow 6 and Blue 1.


**IBDs are serious chronic inflammatory conditions of the human bowel that affect millions of people worldwide. While their exact causes are still not fully understood, studies have shown that dysregulated immune responses, genetic factors, gut microbiota imbalances, and environmental factors can trigger these conditions. In recent years there has been significant progress in identifying susceptibility genes and understanding the role of the immune system and host microbiota in the pathogenesis of IBDs. (source)

Journal reference: Yun Han Kwon, Suhrid Banskota, Huaqing Wang, Laura Rossi, Jensine A. Grondin, Saad A. Syed, Yeganeh Yousefi, Jonathan D. Schertzer, Katherine M. Morrison, Michael G. Wade, Alison C. Holloway, Michael G. Surette, Gregory R. Steinberg, Waliul I. Khan. Chronic exposure to synthetic food colorant Allura Red AC promotes susceptibility to experimental colitis via intestinal serotonin in mice. Nature Communications, 2022; 13 (1).

DOI: 10.1038/s41467-022-35309-y