The Effects of Artificial Dyes on the Gut Microbiome 

Today most people around the world are eating more processed foods than ever before. While these foods are readily available in stores and are often much cheaper than their whole-food counterparts, they can also lead to serious negative effects on our health and well-being. One of the major components added to processed foods is artificial dye. You may have noticed ingredients such as Red 40 or Yellow 6 on the labels of food items you buy (at least in the United States—many other countries have chemical additives). These are just two types of artificial dyes approved for use in food. Even though there are multiple types of artificial dyes that are deemed “safe for consumption” by the Food and Drug Administration in the US, multiple concerns have been raised about their long-term effects on our health, and the appropriateness of their widespread use. An important aspect of our long-term health is the health of our gut microbiome, which may be negatively impacted by artificial colorings.  

What Makes Artificial Dyes Potentially Dangerous? 

Artificial dyes have attracted scrutiny for years due to their chemical compositions. As opposed to natural colorants such as beet extract or grape skin extract, artificial dyes are derived from petroleum. Most of these dyes contain benzidine, which is a known chemical carcinogen that doesn’t occur naturally. The FDA accounts for levels of free or easily absorbed benzidine when they make safety recommendations for artificial dyes. However, many dyes contain bound benzidine, meaning the compound is part of a larger molecular framework that makes up the dye.  

Bound benzidine can still be broken down by the digestive system and absorbed by our bodies, which means we may be exposed to higher levels of the carcinogen than we think. And, research has shown that there is a link between multiple types of artificial dyes and an increased risk of cancer. Aside from being potential carcinogens, artificial dyes are also implicated in a variety of issues ranging from behavioral problems to severe allergic reactions and asthma. In fact, most countries outside of the United States more closely regulate and restrict the use of artificial dyes for this reason. 

What is the Gut Microbiome, and Why is it Important? 

The gut microbiome is a complex ecosystem of bacteria and other microorganisms that live along the digestive tract. Like any other ecosystem, the gut microbiome thrives on diversity. Each type of microorganism that lives there has its own unique purpose, meaning that, in general, the gut microbiome is healthier when various populations of bacteria are in balance with one another. This balance is especially important because some microorganisms can have a harmful effect on the body if they become overabundant. We want enough beneficial bacteria in the gut microbiome in order to keep harmful types in check and maintain a healthy balance.  

The gut microbiome is an essential part of our health, because many of the organisms it contains are responsible for helping the body with important tasks. Gut microbes are involved in all sorts of functions ranging from digestion to hormone production and even mood regulation. When the gut microbiome falls out of balance, many issues can arise including leaky gut, irritable bowel syndrome (IBS), anxiety, and depression. Luckily, one of the primary ways in which we can have an impact on our gut microbiome is with the foods we eat. Since the bacteria live along our digestive tracts, they have access only to the food we give them. In general, minimally-processed, whole-food items tend to support a healthy gut microbiome, while high-fat and high-sugar foods only serve to boost the populations of harmful bacteria. The foods we eat can be a powerful tool for changing the composition of the gut microbiome, both for better and for worse.  

How do Artificial Dyes Impact the Gut Microbiome? 

Since artificial colorings are present in so many foods, it makes sense to investigate their impact on the gut microbiome when evaluating their safety. Even though they aren’t typically consumed in large quantities, dyes can have a significant impact on the gut microbiome.  

In one study looking at a range of food additives, researchers found that artificial dyes such as “titanium white” changed the gut microbial composition to favor pro-inflammatory bacteria. They also observed a reduction in short-chain fatty acid production (which is crucial to proper gut health), as well as overproduction of defensin 𝝱 3 (an antimicrobial peptide). These three factors caused significant increases in gut inflammation and the development of IBS. Additionally, the researchers were able to induce inflammatory flare-ups upon dosage with dyes. This indicates that artificial dyes have a worse impact on people with already compromised or unhealthy gut microbiomes, and suggests that sustained overexposure can lead to IBS and other gut health issues.  

Another study found that phloxine B, a red food dye, has antimicrobial properties against multiple types of bacteria. Researchers observed a decrease in gram-positive bacterial species that corresponded with increased dosage and exposure time. After just 40 minutes of exposure to the dye, the bacteria’s viable population had been reduced by 99.99%. Meanwhile, there was no impact on gram-negative bacteria including Salmonella and E. coli. This illustrates a harmful restructuring of the gut microbiome, as it allows certain types of bacteria to take over larger portions of the gut and removes other types entirely. While antibiotic medicines have their uses, artificial dyes utilized in medications and other ingested substances may have the unintended purpose of damaging the gut microbiome. 

Research also shows that people with unbalanced microbiomes are at even greater risk of developing further issues as compared to those with healthy microbiomes. In the study, researchers found that Red 40 and Yellow 6 both induced colitis in mice with compromised gut microbiomes. However, this increase in gut inflammation was not observed in mice with healthy immune systems. The researchers observed that the presence of certain types of bacteria which metabolize, the artificial dyes caused the already unhealthy mice to develop significant gut inflammation symptoms. While the study did not include human participants, the researchers concluded that their findings are likely applicable to humans in some capacity and that further research would greatly help our understanding of the issue.  

Even though there are many different types of artificial food dyes approved for use today, it’s important that we investigate them further if existing evidence suggests they may not be as safe as they seem. In this case, there is a significant amount of research on the negative effects of artificial dyes on our gut health. While no single study is likely to provide irrefutable proof that artificial food dyes are dangerous for human consumption, we should take what research we do have into account when making decisions about our diet and overall health. As research in the field continues to grow, we will be able to better make a final decision on the safety of artificial colorings. In the meantime, consider looking at alternative food options that utilize natural dyes and avoid these potentially microbiome-damaging chemical colorants. 


Dr. Nicole Beurkens, PhD, CNS

Licensed Psychologist and Board Certified Nutrition Specialist

The world’s leading Holistic Child Psychologist, Dr. Beurkens heads a multidisciplinary evaluation and treatment clinic, is a bestselling author, published researcher, award-winning therapist, and devoted mother of four. In her more than 22-year career, she has supported parents with evidence-based strategies that target the root cause of children’s attention, anxiety, mood, and behavior challenges, empowering them to achieve their highest potential. Dr. Beurkens is a licensed clinical psychologist who holds advanced degrees in psychology, education, and nutrition. 

Collective members are paid sponsors and receive compensation for their content, but all opinions are their own.

  • Hallelujah, finally someone talking about food dyes and microbiome. can we petition PHARMA to stop using dyes in drugs?

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