Published 17th November 2022

What is Bifidobacterium animalis?

ZOE runs the largest study of nutrition and gut bacteria in the world, with data from over 40,000 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. 

Bifidobacterium animalis — or “Billy” as we call him — is one of the 15 “good” bugs. In this article, you can find out more about Billy, why he’s a good bug, and what foods he 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 Billy?

Billy is part of a group of bacteria called Actinobacteria. If you were to look at him under a microscope, you would see that he’s shaped like a rod. 

Our scientists found Billy in the guts of just over one-third of our study participants: 38%, to be precise. 

Actinobacteria are a very large group of bugs. Other members include bugs that make antibiotics and the bug that causes diphtheria.  

Why is Billy a ‘good’ bug?

Researchers have reported that people with obesity have lower levels of Billy than those without the condition.  

In our study, we saw links between having Billy in your gut and having higher insulin sensitivity and lower levels of insulin secretion. 

Higher insulin sensitivity and lower insulin secretion are 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 Billy 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, Billy likes fruit, whole grains, and nuts. Foods that Billy doesn’t like include meat, potatoes, and sugary drinks.

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

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

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

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