What is Roseburia sp. CAG:182 and why is she a ‘good’ bug?

ZOE runs the largest study of nutrition and gut bacteria in the world, with data from over 15,000 people. We publish our research in top scientific journals, including Nature Medicine. Our scientists have found 15 “good” gut microbes that are associated with indicators of good health and 15 “bad” gut microbes that are linked with worse health. 

Roseburia sp. CAG:182 — or “Rosie” as we call her — is one of the 15 “good” bugs. In this article, you can find out more about Rosie, why she is a good bug, and what foods she likes and dislikes. 

Fast facts about your gut microbiome

  • Your gut is home to trillions of bacteria and other microbes that make up your gut microbiome.

  • These microbes mainly feed on fiber and chemicals called polyphenols, which give plants their color, and turn these into chemicals that help support your health and weight control. 

  • Your gut microbiome is unique and radically different from everyone else’s, unlike your DNA, which is 99% the same. Even twins only share 34% of the same microbes. 

  • At ZOE, we use the latest and most advanced biotechnology to analyze the bacteria in your gut from a poop sample.

  • Using this technology, the ZOE program tells you your unique microbiome composition — including which of the 15 “good” and 15 “bad” bugs are in your gut — in order to recommend the best foods for you.

Who is Rosie?

Rosie is part of a group of bacteria called Firmicutes. If you looked at her under a microscope, you would see that Rosie is shaped like a rod.

Our scientists found Rosie in the gut of just over 40% of study participants. 

Other members of the Firmicutes include Lactobacillus, which you may be familiar with already. They are “good” bugs found in foods like yogurt. 

Why is Rosie a ‘good’ bug?

Scientists don’t know much about Rosie yet because she was discovered only very recently. 

In our study, we found links between having Rosie in your gut and having higher polyunsaturated — or healthy — fat levels and lower insulin secretion. 

Lower insulin secretion is good for your body. Too much insulin is bad for your health, as it increases your risk of obesity, type 2 diabetes, and heart disease. 

Other researchers have found an association between Rosie and better inhibitory control, a particular type of cognitive function, which is important when it comes to sticking to long-term goals like healthy eating patterns. 

What foods does Rosie like and dislike?

Our scientists have found links between specific foods that you eat and the 15 “good” and 15 “bad” gut bugs.

Great foods for Rosie are nuts, legumes, vegetables like tomato, zucchini, and bell pepper, and dark chocolate. She doesn’t like potatoes, white bread, animal fats, or sugary drinks. 

But the exact foods that will help Rosie thrive in your body depend on the combination of bugs in your gut. Since every person’s gut microbiome is completely unique, there is no one-size-fits-all diet that is right for everyone. 

The ZOE program analyzes your entire microbiome and works out your unique gut booster and gut suppressor foods, so that good bugs, like Rosie, can flourish.

If you want to know the best foods for your body and your unique combination of gut bugs, take our free quiz today. 


Insulin: Too much of a good thing is bad. BMC Medicine. (2020). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7441661/

Microbiome connections with host metabolism and habitual diet from 1,098 deeply phenotyped individuals. Nature Medicine. (2021). https://www.nature.com/articles/s41591-020-01183-8

Obesity-associated deficits in inhibitory control are phenocopied to mice through gut microbiota changes in one-carbon and aromatic amino acids metabolic pathways. Gut. (2021). https://gut.bmj.com/content/70/12/2283