A new study from UCLA Health has linked gut microbes to brain networks tied to anxiety and depression

In recent years, there has been a growing number of studies that show links between our gut health and mental health, suggesting that our gut microbiota influences our mood and stress responses. In a new study published in the Journal of Nature Communications, researchers from UCLA Health have revealed that our gut microbiome in early childhood may influence our risk of developing depression and anxiety. 

The observational study found that young children whose gut microbiome had higher levels of certain kinds of bacteria (the Clostridiales order and Lachnospiraceae family) were at higher risk of experiencing internalising symptoms (including depression and anxiety) during middle childhood. These findings suggest that our early gut bacteria may play a role in shaping brain circuits that affect our emotional health later in childhood. 

Study senior author, Dr Bridget Callaghan from UCLA Health, commented, “By linking early-life microbiome patterns with pain connectivity and later symptoms of anxiety and depression, our study provides early evidence that gut microbes could help shape mental health during the critical school-age years.”

While there have been previous studies into the gut-brain axis in children, these have primarily focused on infants and toddlers, rather than school-aged children. Past studies have examined how gut composition might relate to early brain development around movement, language, and learning, rather than mental health. This new study sought to find out if young children’s gut microbiomes may have an effect on their mental health outcomes later in childhood, when depression and anxiety may be more likely to first appear. 

Research findings highlight the potential for early mental health interventions through diet and probiotics; however, Dr Callaghan said that further research is still needed to find out whether these associations found during the study are causal and should be acted on. 

The study was based on data collected from the Growing Up in Singapore Towards Healthy Outcomes (GUSTO) study, a longitudinal birth cohort study. The GUSTO study collected various health data from children, including stool samples at age two, resting state MRI brain scans at age six, and survey data from caregivers about behavioural problems at age seven-and-a-half. The UCLA Health study went on to use data from 55 of these participants to examine how early gut microbial profiles at age 2 were linked to brain patterns at age six.

The gut-brain connection

The link between your gut and brain, known as the gut-brain connection, is an area where more research is currently going on. This is in hopes of helping us develop a greater understanding of the impact gut health has on our overall mood and mental health.

Rosie Letts, BSc Hons, MBANT, CNHC, Nutritionist and Functional Medicine Practitioner, explains more about the gut-brain connection.

“The gut-brain axis is a two-way communication pathway between the gut and the brain, primarily mediated by the vagus nerve, immune system signals, and neurotransmitters produced in the gut. Recent studies suggest that gut microbiota influence brain function through their ability to produce neurotransmitters such as serotonin, dopamine, and gamma-aminobutyric acid (GABA), which regulate mood and anxiety. 

“[An estimated] 90% of the body’s serotonin - a neurotransmitter crucial for mood regulation - is produced in the gut. Disruptions in the gut microbiome can lead to imbalances in these neurotransmitters, potentially contributing to mental health issues like anxiety, depression, and stress.”

Past studies into the links between our gut’s influence on the brain have shown a reduction in anxious behaviours in animals following the introduction of gut bacteria into germ-free mice, while a more recent 2022 study revealed that mice’s gut microbiomes influenced their motivation to exercise. Faecal transplants from humans with depression into rats have also shown an increase in depression and anxiety-like behaviours. Past studies have also shown that mental health can affect gut health, whether directly (through signals from your brain to your gut) or indirectly (through turning to comfort foods when stressed, which can change your microbiome).

Studies suggest that our gut microbiota influences our brains. But how can we influence our gut to ensure our microbiota is as healthy and diverse as possible? 

“Diet is one of the most significant factors influencing the composition and diversity of the gut microbiome. A diet rich in dietary fibre from vegetables, fruits, legumes, and whole grains promotes the growth of beneficial bacteria,” Rosie explains.

In addition to having a varied diet, eating a variety of fermented foods can help promote good gut health, while avoiding highly processed foods, refined sugars, and unhealthy fats can help avoid a reduction in microbial diversity, which can lead to dysbiosis (an imbalance in your gut microbiome).

As explained by Nutritionist Resource, our gut health can have a significant impact on our mental health and wellbeing. A healthy digestive system doesn’t just help us to better absorb the nutrients, vitamins and minerals we need, but our gut also affects our immune system and resilience to stress, both of which can further impact our mood.  

Working with a nutritional expert can help you to learn more about eating a balanced, nutritious diet to look after yourself in body and mind. A balanced, healthy diet contains vital nutrients your brain and gut both need in order to help support your overall health. Working with a nutritionist can be helpful in ensuring you are getting the right foods for your particular circumstances. 

While there’s still much to learn about the gut-brain connection, it’s good to be reminded that small, everyday choices in how we eat, move, and care for ourselves may not only shape our physical health, but our emotional wellbeing, too. We must just be able to support our mental wellbeing with a few simple changes to how we eat and how we look after our gut.