While you may believe that avoiding brightly coloured foods means avoiding synthetic dyes, this is not always the case.
And they could be wreaking havoc on your gut.
Recently, a University of Guelph study revealed the harmful effects of food dyes on gut health.
The food dyes that were researched included amaranth, allura red, sunset yellow and tartrazine. It may surprise you to find out just how common food dyes are in the American food industry.
They are often ingredients in drinks, frozen desserts and cereal, all of which are familiar household food items. (1)
Spotting Artificial Dyes in Your Food
Observing the colour of a food product is not a sure-fire way of spotting artificial food dyes that can harm your gut health. According to Dr. Céline Gounder, a CBS News medical contributor, “Even white foods may have synthetic dyes to make it brighter.” A more reliable way of limiting food dye intake would be to read the labels of food products you consume. (2)
The Dangers of Artificial Food Dyes
So, what makes food dyes potentially harmful to our gut? Artificial food dyes have been shown to disrupt the gut microbiome, potentially causing inflammation and discomfort. Emma Allen-Vercoe, a molecular biologist and University of Guelph professor, has found that “the human part of your body can’t do anything with them.” Instead, the microbes in your gut break them down, though this results in a product that can be toxic to your cells. (3)
Artificial food dyes can kill beneficial bacteria. This leads to difficulty in proper food digestion. In fact, some known side effects of ingesting too much food dye include bloating and pain. (4) But it doesn’t just stop there; having a healthy gut microbiome is key to your overall well-being.
The Link Between Gut Health and Immunity
Health starts from the gut, and that includes our immunity. Having a healthy gut microbiome is essential to maintaining a healthy immune system.
Our gut is home to tens of trillions of microbes, many of which are bacteria that keep our bodies healthy. However, our bacteria can change over time depending on our age, lifestyle habits, and whether or not we take antibiotics. As such, unhealthy lifestyle habits (such as regularly consuming artificial food dyes) or the use of antibiotics can cause dysbiosis, a state that occurs when the balance in our microbiome is interrupted. This leads to the weakening of your gut’s defenses, leading to infections, chronic inflammation or even diseases such as diabetes or heart problems. (5)
(Tip: Need help keeping your gut health on track? Visit our blog post on gut health and immunity here!)
Shockingly, synthetic food dyes are not only found in common food items, but are present in vitamins and supplements as well. This is especially true for prenatal and children’s vitamin tablets and gummies, which often come in bright colours for added visual appeal and branding purposes. Currently, the FDA’s food dye intake recommendation is not tailored for sensitive populations, including pregnant women and children. The effects of consuming these synthetically dyed vitamins regularly (and often frequently, for pregnant women) remain relatively unknown. (6)
What's the Alternative?
If artificial food dyes pose the risks that they do, why are they so heavily integrated into the American food industry?
The way food appears is often what makes it appealing, making us more likely to purchase and consume it. Protecting our gut health doesn’t mean having to compromise and disregard visual appeal, though; natural food dyes such as beetroot, turmeric and spirulina are safe and healthy alternatives you can include in your everyday diet. Not only are they natural alternatives, but they are also beneficial to your overall health and well-being. (2)
What Does This Mean for Your Diet?
The point isn’t to eliminate food dyes and strictly monitor everything you eat; it is only natural to consume foods that we find visually appealing, after all. More importantly, being educated about the risks that artificial dyes can pose allows you to be conscious of the amount you consume regularly while introducing other healthier options.
By carefully selecting foods based on their ingredients, you can make educated decisions for your health and minimize disruptions to your gut microbiome.
Want to learn more about the ingredients you should watch out for? Visit our blog on common fillers found in supplements!
References:
1: Sujani Rathnayake, “Gut Reactions: U of G Study Finds Food Dyes Can Harm Gut Microbes,” U of G News, April 23, 2025, https://news.uoguelph.ca/2024/07/gut-reactions-u-of-g-study-finds-food-dyes-can-harm-gut-microbes/
2: Sara Moniuszko, “What Artificial Food Dye Bans Mean for Your Health and Fridge,” ed. Nicole Brown Chau, CBS News, accessed June 25, 2025, https://www.cbsnews.com/news/food-dye-ban-red-health/
3: Cameron Mahler, “Q and A: Why This Microbiologist Is Warning People Not to Ingest Some Food Dyes | CBC News,” CBCnews, July 6, 2024, https://www.cbc.ca/news/canada/kitchener-waterloo/q-and-a-why-this-microbiologist-is-warning-people-not-to-ingest-some-food-dyes-1.7255454
4: Renee Bergmen, “Why Are Food Dyes Bad for Your Stomach? - Metastory Health: Holistic Healing for the Gut Brain Axis,” Metastory Health | Holistic Healing for the Gut Brain Axis, October 29, 2024, https://www.metastoryhealth.com/blog/why-are-food-dyes-bad-for-your-stomach
5: Ji Yoo et al., “Gut Microbiota and Immune System Interactions,” Microorganisms 8, no. 10 (October 15, 2020): 1587, https://doi.org/10.3390/microorganisms8101587
6: A. L. Lehmkuhler, M. D. Miller, A. Bradman, R. Castroina, and A. E. Mitchell, "Certified Food Dyes in Over-the-Counter Medicines and Supplements Marketed for Children and Pregnant Women," Food and Chemical Toxicology 143 (2020): 111499, https://doi.org/10.1016/j.fct.2020.111499.