Socially Anxious Microbes: The Bugs in Your Gut Might be Causing Your Anxiety

Almost everyone has felt some level social anxiety before, but for some, the crippling affliction is a massive weight they carry through life.

While there are some treatments available, like cognitive behavioural therapy, lifestyle changes, or medications, many still suffer in silence.

A new treatment approach gaining attention lies within the gut, specifically the microbes living inside.

Groundbreaking research continues to unveiled strong relationships between the gut and the mental activity. These gut microbes are now known to interact with our brain and influence how it functions, impacting our decision-making and mood.

Interestingly, certain microbial populations seem to influence the brain in a way which specifically produces social anxiety. This specificity highlights just how deeply intertwined our emotions are with the microscopic world within us.

Understanding The Gut-Brain Connection

The human gut is often called the second brain because of its extensive and complex network of nerves. This network is called the enteric nervous system (ENS) and contains more than 100 million neurons embedded in the walls of the gastrointestinal tract, stretching from the esophagus to the rectum. The ENS has more neurons than the spinal cord and can operate independently of the brain, controlling digestion and gut function on its own

The neurons in the gut (ENS) communicate directly with the neurons in the brain (CNS) through neural pathways like the vagus nerve. Like most conversations, this communication is bi-directional, with both participants listening and speaking. In addition to signalling via nerves, the “gut-brain-axis” involves chemical signalling. Neurons in the gut, but also non-neuronal gut cells, and even microbes can synthesize hormones, neurotransmitters, neuroinhibitors or other signalling molecules which communicate information to the brain.

This perpetual conversation creates a situation where issues in one can lead to issues in the other. Most of us have experienced the stomach upset which can accompany mental stress or anxiety. Chaos upstairs can cause chaos downstairs in the absence of any actual gut issues. When thinking of the opposite direction, we might imagine stomach upset from something we ate dominating our attention and making it hard to focus on anything else. It might also induce fear around not making it to the toilet.

However, the influence of gut issues on our mind goes beyond the direct experience of the digestive discomfort. We might not even consciously know our gut is having issues, experiencing no pain or clear signals. Yet, our gut still may be impacting our mind in ways we aren’t aware of, like influencing our cravings, making us quick to anger, or making us socially anxious. One of the main ways it can do this is through the microbes living within it.

The Microbial Ecosystem in our Gut

Living among the human cells in our gut is a complex ecosystem of microbes (bacteria, fungi, viruses, archaea). We exist in co-dependent relationship with this ecosystem, providing the microbes a home and nutrients, while they perform essential functions for us. Simply put, we could not survive without them. They help us breakdown certain foods, synthesize essential nutrients we can’t produce ourselves, train our immune system to know what is friend vs. foe, and prevent harmful bacteria or toxins from entering the bloodstream.

Since we are so reliant on this microbial ecosystem, its health is directly related to ours. Like the larger ecosystems we are more familiar with, such as that of a forest or lake, it can be threatened by the removal of a species, or the addition of an invasive one. Also, like other larger ecosystems, one of the best markers of health is diversity.

Diversity enhances the stability and resilience of the ecosystem. A diverse forest is more resilient to a fire or infection than a mono-culture. When there is diversity, multiple species might be performing the same function, adding redundancy that protects the overall health, should a disturbance knock out one species. Diversity also makes it more likely that there will be species immune to a certain disturbance.

Given our reliance on the microbial ecosystem and the importance for diversity on its health, it is no surprise that hundreds of studies have shown that gut microbial diversity is associated with all sorts of positive health outcomes, both from a gut and whole-body perspective. On the flip side, lack of microbial diversity, under population of certain beneficial microbes, or overpopulation of certain harmful microbes, are all associated with negative health outcomes. Altered diversity (dysbiosis) is associated with major diseases such as obesity, diabetes, cardiovascular disease, cancer, hypertension, and inflammatory bowel diseases.

The Causal Role of Microbes in Social Anxiety

Dozens of studies have demonstrated a link between dysregulation of the gut microbiome and mental disorders like depression and anxiety. However, it was previously unclear what was driving this link, and to what degree the microbes were affecting the brain, versus the depressed or anxious mind influencing the gut.

In 2023, Ritz and colleagues published a pivotal study demonstrating that gut microbiota could play a causal role in social anxiety. By transplanting gut microbes from individuals with social anxiety disorder into healthy mice, the researchers observed a marked increase in social fear responses. Interestingly, the mice didn’t demonstrate other anxiety-like behaviours or depression, highlighting that the effects were targeted toward social fear. Specific bacterial species, such as Phocaeicola massiliensis, were found to be elevated in socially anxious individuals, suggesting potential culprits for this altered behaviour.

How are microbes causing social Anxiety?

Through studying the mice, Ritz and colleagues determined that microbes from people with social-anxiety disorder are likely altering the communication lines that keep the brain calm. In mice given these “socially anxious” microbiomes, the hypo-thalamic pituitary adrenal (HPA) axis was dysregulated. This axis plays a key role in the stress response, and its dysregulation could make an individual more sensitive to perceived threats. The mice also ended up with compromised blood-brain barriers, which allows molecules in which can interfere with proper brain functioning. Finally, the mice were shown to have reduced oxytocin signalling. This bonding hormone normally buffers social stress, and its reduction would make social interactions feel more threatening.

Pinpointing exactly which aspects of the gut microbiome are exerting each effect is challenging. The general takeaway from researchers was that the overall microbial ecosystem is interacting with the nervous system in complex ways, tilting the mind towards anxious isolation. We come back to the idea of the broad ecosystem. The important thing being the sum total of all microbes urges us to consider the overall health of our ecosystem.

Healing the Microbial Ecosystem

Recognizing that a dysregulated gut microbiome can contribute to social anxiety and numerous other negative outcomes, the logical next step is investigating how we can cultivate a healthy ecosystem. Luckily, there are a number of proven strategies.

1. Optimize Your Diet

Add gut-friendly foods to your meals:

• Probiotic foods like yogurt, kefir, kimchi, sauerkraut and kombucha introduce beneficial bacteria into your system. Having these bacteria flourish makes it harder for harmful ones to invade.
• Prebiotic foods are high in fiber, which feeds gut microbes. Not all fiber is the same, each plant has a unique fiber profile, and each microbe prefers different types of fiber. Eating a diet rich in plant diversity is a direct way to cultivate microbial diversity.
• Polyphenol-rich foods like green tea, dark chocolate, and berries also support healthy gut flora.

2. Manage Stress Levels

While the Ritz study discussed above demonstrated a causal link between certain microbial ecosystems and social anxiety, it is likely that anxiety itself played a role in cultivating these ecosystems. Stress can wreak havoc on gut health, and stress management techniques can have a dual benefit for your mind and microbiome. Practices such as deep breathing, mindfulness meditation, or progressive muscle relaxation help regulate cortisol levels and keep gut bacteria thriving. Any psychotherapy techniques like cognitive behavioural therapy which are able to reduce anxiety are also likely to help.

3. Get Moving

Across dozens of human and animal studies, exercise has consistently been associated with improved microbial diversity. It has also been shown to selectively increase the populations of microbes known to be beneficial and decrease those known to be destructive. Interestingly, the positive effects seen from exercise on the microbiome seem to go away if we stop exercising for a prolonged period, stressing the importance of consistency.

Don’t Let Your Mind Become Hijacked

The idea of microbes influencing the way our mind works might sound far-fetched, but the animal world is filled with much stranger things. Toxoplasma gondii is a single-celled protozoan parasite which reproduces in the intestines of cats. In order to make its way into the cat, it infects the brains of rodents and rewires their fear of cats into an attraction so they end up as lunch. The insect world is filled with parasitic mind control examples like this, but another mammalian example is that of rabies. Since rabies can be spread through saliva, infected hosts (including humans) have their minds hijacked into rage, while simultaneously becoming terrified of drinking water, which would dilute the virus out of the saliva.

Our brains are easily hijacked. Our mind is software being run on the hardware of billion of neurons in a web of communication. Microbes, whether they be bacteria, viruses, or fungi, have evolved to make our bodies their home and are not passive bystanders. They actively participate in this neural web of communication and influence the software of our minds as a result. It is crucial that we recognize the importance of our microbial ecosystems and ensure our dietary and lifestyle choices cultivate ecosystems which serve us.

Microbes are not the only things hijacking our minds. In the Energetic Investor I detail the various ways our software can become infected. Grab your copy today, and subscribe to our newsletter to stay up to date on the latest Energetic Insights.