Get full access to Outside Learn, our online education hub featuring in-depth nutrition, fitness and adventure courses, and more than 2,000 instructional videos when you sign up for Outside+..
Science has taught us so much about the microbiome in recent years, but there’s still something new to learn about gut health every day. And the importance of the gut-brain axis is becoming increasingly key to answering some of our biggest health questions – including those around mental health. Changes within the gut and its bacterial makeup can have a positive impact on your mental health, but it’s still unclear just how much of an influence it wields over your well-being.
Now, research is suggesting that the link between your gut and your mental health may be particularly strong when it comes to anxiety. Find out how your microbiome might be influencing your anxiety symptoms.
Certain gut bacteria may make you more likely to experience anxiety
A research study published in Nature indicates that researchers have found that a particular molecule created by gut bacteria can encourage anxiety-like behaviors. While previous research has suggested that the microbiome can influence brain function and mood, and that individuals with certain neurological conditions have a different gut bacteria composition, this new study specifically looked at how what’s happening in the gut can signal behavioral changes.
The researchers examined one particular bacterial metabolite (or a by-product of gut microbes) called 4EPS, or 4-ethylphenyl sulfate. This metabolite is usually created in the intestines, absorbed in the bloodstream and then sent throughout the body in humans and mice. And past research suggests that when higher levels of 4EPS are present, it may be linked to neurological differences like autism and schizophrenia in mice and human models.
In the Nature study, researchers specifically looked at the impact of the 4EPS metabolite on mouse models of anxiety. Their goal? To better understand anxiety disorder in humans, using an animal model that can more precisely show the changes in the brain and body that may cause those anxiety-induced symptoms. Researchers defined “anxiety” in mice as hiding rather than naturally exploring.
They divided mice into two groups: One colonized with bacteria engineered to produce 4EPS, one control group colonized with bacteria that couldn’t produce 4EPS. Then, the team introduced both groups into a new environment to measure their behavior.
In this new arena, the mice with higher levels of 4EPS spent significantly less time exploring their new surroundings and more time in hiding, compared to the control group. This suggested they had higher levels of anxiety for researchers. Additionally, brain scans of the high-4EPS group showed that the areas of the brain associated with fear and anxiety were more activated; plus, there were changes in the functional connectivity and brain activity of these mice.
And, more specifically, the researchers discovered a certain kind of cell – oligodendrocytes – were altered by the presence of 4EPS. Oligodendrocytes are cells that produce myelin, the protective coating that wraps around neurons and nerve fibers. With 4EPS present in higher amounts, those cells produce less myelin and create thinner insulation, a factor that may potentially influence anxiety, its symptoms or anxious behaviors. When the 4EPS group of mice was given a drug to increase myelin production, their anxious behaviors were reduced.
What does this mean for humans?
Although this intriguing study was conducted on animal models, it holds a lot of promise and potential for humans. The researchers suggest that it’s a first-step proof-of-concept that shows how gut microbes and metabolites can influence the brain – and potentially your mental health.
While increasingly more research has confirmed the link between the gut and the brain, it’s been a challenge for scientists to pinpoint exactly how the gut and mental health may be connected. This study suggests that the presence of particular metabolites (specifically, that 4EPS metabolite) may make you more likely to experience anxiety or anxiety-like behaviors. And changes within your gut microbiome might potentially shape anxiety and other mental health shifts.
Wondering what you can do to lower your 4EPS levels? Well, there’s not much you can do right now. This research is still new and needs to be explored further; however, it can offer some guidance if you’re hoping to nourish both your gut and your mind with healthy foods. Feeding your gut is essentially feeding your brain, and promoting the growth or presence of beneficial gut bacteria may help you manage or soothe some symptoms of anxiety.
Check out some of our favorite gut-healthy habits for overall wellness: