What is Eubacterium eligens 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. 

Eubacterium eligens — or “Ellie” as we call her — is one of the 15 “good” bugs. In this article, you can find out more about Ellie, 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 Ellie?

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

Our scientists found Ellie in the gut of most people — 92.5% of our study participants, to be precise. 

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 Ellie a ‘good’ bug?

Scientists don’t know much about Ellie yet. But one group of researchers found that she can promote the production of anti-inflammatory molecules in a lab study in cells.

A small study with human volunteers found that people with less belly fat had higher levels of Ellie. 

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

Lower insulin secretion is good for your body. Too much insulin isn't good for your health, as it increases your risk of obesity, type 2 diabetes, and heart disease. 

What foods does Ellie like and dislike?

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

In general, Ellie likes vegetables — particularly zucchini, spinach, and tomato — fruit, nuts, fish and seafood, full-fat yogurt, and eggs. She doesn’t like potatoes — particularly potato chips — pizza, chocolate bars, or animal-derived foods. 

But the exact foods that will help Ellie 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 Ellie, 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. 


A metagenome-wide association study of gut microbiome and visceral fat accumulation. Computational and structural biotechnology journal. (2020). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7528071/

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 

Prebiotic potential of pectin and pectic oligosaccharides to promote anti-inflammatory commensal bacteria in the human colon. FEMS Microbiology Ecology. (2017). https://academic.oup.com/femsec/article/93/11/fix127/4331632?login=true