What Is the Blue Poop Challenge?

The Blue Poop Challenge tracks your gut transit time and can reveal some interesting secrets about your digestive system. The time it takes for food to travel through your digestive system can reveal a lot about your gut health.

How does the Blue Poop Challenge work? You essentially consume blue dye and then watch your bowel movements until you make blue poop.

Everybody poops. The shape, size, consistency, smell, frequency, and color of poop varies widely from person to person. These are not the only qualities that can reveal information about your health. A team of scientists—part of a nutrition research company called ZOE—used blue poop to study another way to measure gut health.

Anyone can participate in ZOE’s Blue Poop Challenge: By eating muffins baked with royal blue food dye, which turns your poop blue, you can track how long it takes food to travel through your gut.

In a study, researchers concluded that gut transit time may tell you more about how your gut functions than stool consistency and frequency. Gut transit time is how long it takes food to travel through your gut.

“Poop is like a message from your gut, and it has a lot to say,” gut health nutritionist Amanda Sauceda, RDN, said in a ZOE video about the challenge. “The color, the consistency, how often you’re pooping, how long it takes food to move through your gut reveals a lot about what is happening inside of you.”

The researchers found that blue poop is a marker of gut transit time, which allows you to measure how quickly it takes to digest and excrete blue food. This is how the Blue Poop Challenge works.

You need to first bake some blue muffins. Follow the recipe, per ZOE, which lists all of the ingredients you need and step-by-step instructions. The most important ingredient is royal blue food dye. You can purchase a blue muffin directly from ZOE if you are not a skilled baker.

Once you have your blue muffins, it’s time to eat. Enjoy two blue muffins for breakfast. Be sure to make a note of the time, then let nature take its course. As you wait to have a particularly colorful bowel movement, you can eat whatever you want—no matter the color—for the rest of the day, Will Bulsiewicz, MD, gastroenterologist, explained in the video.

When you finally see blue poop show up in the toilet, make another note of the time. Visit ZOE, where you can plug in the times you ate the muffins and when you noticed blue poop. The website also asks for information about your height, weight, and general diet habits.

Based on all of the data, ZOE populates what it refers to as your “poop personality,” which includes your gut transit time, as well as what you can work on to improve your gut health. It will compare your gut transit time to others who took the challenge and give you personalized gut health tips.

The researchers recruited 1,000 people to test the Blue Poop Challenge. They found that gut transit time lasted anywhere from less than 12 hours to several days. The median time was approximately 28.7 hours. The researchers compared these times to microorganisms found in stool samples to understand each person’s gut microbiome.

Your gut microbiome is where trillions of microorganisms—such as bacteria and fungi—live and help your digestive system break down food. It helps absorb nutrients that maintain your gut health.

Knowing how well your gut microbiome works is important to understanding your gut health. Your gut microbiome plays a role in supporting your digestive and immune systems. It also affects your weight, blood sugar levels, and cholesterol.

In the Blue Poop Challenge study, shorter gut transit times generally corresponded to better gut health, less abdominal fat, and healthier responses to food than longer gut transit times. The connection between your gut transit time and gut health is complex. The Blue Poop Challenge is only one way to understand that connection.

“The key to health and weight loss lies not in the latest fad diet or calories consumed, but in the microbes inside us,” Tim Spector, MD, professor of genetic epidemiology at King’s College London in England, said in a press release from Cision PR Newswire. “The Blue Poop Challenge is a simple way to find out what is going on in your gut. All you need are a couple of blue muffins and a spirit of curiosity to take that first step.”

Like the participants in the study, you can also participate in the Blue Poop Challenge to measure your gut travel time and learn about your gut health. As the scientists behind the Blue Poop Challenge point out, this information cannot diagnose, prevent, or treat any health condition. You should consult a healthcare provider if you have any concerns about your poop or digestive system.