A new study of more than 34,000 people sheds light on what a healthy gut microbiome may consist of

Our gut microbiome has a huge influence on our health and wellbeing. Everyone's gut microbiome is unique. It contains helpful 'good' bacteria, some potentially harmful bacteria, and pathogenic 'bad' bacteria. Your gut microbiome sends signals to your brain via the vagus nerve. This connects your gut directly to your brain. But it’s not just that physical connection that is important. Your gut microbiome affects your body and mind more than you might think. 

What does your gut microbiome do? 

Your gut microbiome helps digest food and fibre. It also makes vitamins and supports your immune system. Plus, it plays a part in your mental health through the gut-brain axis. It’s estimated that around 90% of the serotonin we have is made in our gut. This means that if your gut is out of balance, you may struggle to regulate your mood.

Your gut biome does more than produce nutrients and vitamins. It also protects against pathogens and keeps the gut barrier strong. This stops harmful substances from getting into your bloodstream. Research suggests that our gut microbiome sends signals to the brain. This influences our mood. Recent studies have even suggested that our gut microbiome affects how we age, and how our gut microbiome is when we are children could affect our future emotional health.

New research reveals what a healthy gut microbiome actually looks like

What we know about our gut microbiomes and how they affect us has increased in recent years. However, until recently, we weren’t entirely clear what makes a healthy gut microbiome. Now, thanks to a new study, we are closer to understanding the mix of microbes that suggests someone has low inflammation, healthy cholesterol levels, and good immunity. 

Learning about your gut biome is simple with home testing kits. However, how useful those home testing kit results are has been questioned. We weren't sure what makes a ‘good’ microbial mix, meaning we don’t necessarily know what areas to target to try and improve. Diversity has been the main factor experts have looked for.

Links between our diet, gut microbiome, and health are complex. Thanks to this new research from researchers at the University of Trento in Italy, we are closer to understanding than before. Researchers looked at data from over 34,500 people across the UK and USA who took part in the PREDICT programme. The results were validated against data from 35 other groups across Western countries. 

Researchers focused on 661 of the thousands of species of bacteria living in our gut. These 661 were found in over 20% of participants. They used this data to find 50 bacteria linked to good health markers like BMI and blood glucose levels. They also identified 50 bacteria most associated with poor health. Of the 50 ‘good’ species, 22 were new to science. These 22 seemed to influence four key areas: cholesterol levels, inflammation and immune health, body fat distribution, and blood sugar control. 

Research suggests that health outcomes, both good and bad, may hinge on the gut microbiome. It helps release chemicals that support cholesterol transport, fat metabolism, insulin sensitivity, and reduce inflammation.

Links between microbes and the diet of those who took part were assessed using food questionnaires, and data logged using the Zoe app. The app suggested that those taking part should try to eat at least 30 varieties of plants each week, three or more fermented food portions a day, have lots of fibre, and minimise how many ultra-processed foods they ate. 

Out of the 661 microbes studied, researchers found that most were either linked to a healthy diet and better health or to a poor diet and worse health. However, 65 microbes were more complex and didn’t fit with this pattern. Researchers think other microbes might influence these. They could be impacted by certain diets or a specific strain of bacterium. This new research has allowed researchers to create a new ranking scale (from 0 to 1,000) to rank the overall health of an individual’s gut microbiota. 

Researchers emphasise that, while this is a great step forward towards our understanding of how our gut microbiomes work, more research is still needed to better understand what makes a healthy gut microbiome. Our diet, environmental factors, age, and other health conditions all affect our gut microbiome. Bigger studies are still needed to uncover more links and establish what a healthy gut microbiome looks like. 

As complex as the gut microbiome may be, this new research is a reassuring reminder that small, everyday choices can support our health and wellbeing. And happily, supporting them doesn’t require perfection—just curiosity, colour on your plate and a few everyday habits that make you feel good. Your gut is wonderfully adaptable, and even little changes can make it happier over time.