Red Dye & Gut Health

Eating whole foods is beneficial because whole foods are replete with key nutrients. However, eating whole foods also means avoiding processed foods, which is an important dietary strategy as well. Avoiding processed foods means eliminating additives and preservatives that might seem insignificant, but a recent study has shown that long-term consumption of red food dye, a common food additive, can be a potential trigger of inflammatory bowel diseases (IBDs), Crohn’s disease and ulcerative colitis. Diet plays a pivotal role in the development of IBD and IBD incidence has seen a rapid rise in developing countries with western diets that are high in food additives.

Study author Wiliul Khan of McMaster University said the dye is a common ingredient in candies, soft drinks, dairy products and certain cereals. Dyes are generally used to make foods more appealing to children, be it the color or the texture, and the use of synthetic colorants in food products has increased over the past 50 years. These compounds generate free aromatic amines in the gut lumen where they can be considered mutagenic and carcinogenic. The dye directly disrupts gut barrier function, increases the production of serotonin, and alters gut microbiota composition, all of which leads to an increased susceptibility to colitis.

Serotonin or 5-hydroxytryptamine (5-HT) regulates GI physiological function in response to environmental stimuli in the gut. 5-HT content was found to be elevated in IBD patients, and mice with lower 5-HT content in the gut showed reduced colitis severity.

In this study, C57BL/6 mice were either fed a normal chow diet or one exposed to red dye for 12 weeks. Red dye levels were calculated based on the acceptable daily intake (ADI) in humans (7 mg/kg per body weight). Mice exposed to red dye showed reduced body weight, increased disease activity, reduction in colonic lengths and increased colonic weights. In addition, colonic interleukin (IL)--1β, IL-6, and tumor necrosis factor (TNF)-α, were higher in the mice exposed to the red dye, while the genes that regulate intestinal epithelial barrier function (zonula occludin-1 [ZO-1; Tjp1], and occludin [Ocln]), were reduced compared to their counterparts.

"The literature suggests that the consumption of Allura red dye also affects certain allergies, immune disorders and behavioral problems in children, such as attention deficit hyperactivity disorder," says Khan. “While the exact causes of IBDs are not fully understood, dysregulated immune responses, genetic factors, gut microbiota imbalances, and environmental factors are triggers.”