Scientists Want You To Turn Your Poop Blue

The internet has asked people to do numerous strange things before, from eating spoonfuls of cinnamon to planking. But now it wants you to turn your poop blue—for your own good, of course.

Research group ZOE, and the scientists behind it, is encouraging people to test their gut health using an innovative, and easy, at-home technique. The "Blue Poop Challenge" was established by the group on May 18.

How fast you pass food can reveal a lot about your gut health and the kind of bugs you have. ZOE's "Blue Poop Challenge," involves purposely causing your poop to turn blue in order to track how long it takes you to pass the food.

ZOE is challenging people to eat two muffins made with blue food coloring in the morning, while noting what time you ate them. It's then down to you to keep track of when you pass a stool with a blue or green color, and jot that time too.

Next, you just need to visit the research group's website,, and enter your details and times. ZOE does all the hard work for you and calculates a "personality" for your poop and gut health.

Blue muffins
Blue muffins for the "Blue Poop Challenge". Image courtesy of ZOE. ZOE

In a study by ZOE, normal transit times ranged from less than 14 hours to days, with the average time being 29 hours. The study also revealed that shorter transit times often mean better health, less abdominal fat and healthier food responses. Your transit time can also tell you a lot about microbes in your gut, which are the trillions of bugs that live there.

"With longer transit times, we often found more microbes that feed on protein and fewer fiber-loving bugs that produce helpful molecules called short-chain fatty acids that are linked to better gut health," reads a press release by ZOE.

"Interestingly, we also found that people with longer transit times were more likely to have a greater diversity of microbes in their gut, which is often associated with better gut health. This suggests that more microbiome diversity may not always be a sign of better health for people who don't poop very often.

Calculations also provide advice on what foods you should be incorporating or minimizing from your diet, after you fill out a diet survey.

The challenge has even been shared on TikTok, after popular baker @bakinghermann shared his recipe for the muffins on May 18 to over one million views.

ZOE has a blue muffin recipe available, which includes a necessary 1 tsp of blue food dye. Alternatively, they have muffins available to purchase online that include enough for two people to try out the "Blue Poop Challenge."


Test your own gut health with this science experiment. More info on my IG #BluePoopChallenge #guthealth #muffins #asmr #bluefood

♬ original sound - Julius Fiedler