What is Clostridium sp. CAG:167 and why is he a ‘good’ bug?

ZOE runs the largest study of nutrition and gut bacteria in the world, with data from over 10,000 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. 

Clostridium sp. CAG:167 — or “Claude” as we call him — is one of the 15 “good” bugs. In this article, you can find out more about Claude, why he is 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 Claude?

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

Our scientists found Claude in the gut of around 40% of our study participants. 

There are many different species of Clostridium, including some that can cause serious disease, like botulism, tetanus, and food poisoning, and others that are beneficial and play a key role in maintaining a healthy gut. 

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 Claude a ‘good’ bug?

Scientists only discovered Claude recently and don’t know much about him yet. 

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

Lower insulin secretion and higher insulin sensitivity are 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. 

What foods does Claude 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, Claude likes brown rice, wholemeal pasta, dark chocolate, lentils, and unsalted nuts. He is also fond of alcohol. He doesn't like potatoes, white bread, or sugary cereals.

But the exact foods that will help Claude 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 Claude, 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.


About botulism. (n.d.). https://www.cdc.gov/botulism/general.html

Commensal Clostridia: leading players in the maintenance of gut homeostasis. Gut Pathogens. (2013). https://gutpathogens.biomedcentral.com/articles/10.1186/1757-4749-5-23

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 

Prevent illness from C. perfringens. (n.d.). https://www.cdc.gov/foodsafety/diseases/clostridium-perfringens.html

Tetanus. (n.d.). https://www.cdc.gov/tetanus/index.html