You may have heard of probiotics—they’re those “good bacteria” that live in your gut. In the past decade probiotics have become well-known for their essential role in maintaining healthy gut flora, and probiotic-containing foods like yogurt, sauerkraut, and miso have become renowned for their health benefits. However, recent studies show that the benefits of probiotics extend well beyond digestion: probiotics can also have a positive impact on mental health and may be a valuable addition to the tool box for psychiatrists and psychotherapists practicing holistic care.
Probiotics and the Gut-Brain Axis
Probiotics work to optimize the gut flora in your body, which collaborates with your nervous system and brain in a complex system known as the “gut-brain axis.”
In 2016, researchers published an analysis of seven scientific studies which confirmed that through the gut-brain axis, probiotics can improve brain function, balance hormones, boost the immune system, and reduce inflammation—all of which can have positive effects on mental health conditions such as anxiety and depression (McKean, Naug, Nikbakht, Amiet & Colson, 2016).
1. Improve Brain Function
The gut-brain axis is a two-way interaction—meaning the brain can affect the gut, and the gut can affect the brain. The body uses immune pathways, neural pathways, and metabolic pathways to send signals back and forth along this complex network. It may seem obvious that an unhealthy gut flora can lead to physiological problems such as obesity and IBS—but because of the gut-brain axis, unhealthy gut flora can also have a negative impact on brain function, cognition, and behavior. Probiotics help the gut flora to remain in balance, which encourages healthy brain function and therefore has a positive effect on mental health.
Various nutrients, toxins, and antigens present in our gut can activate the release of hormones that affect physical and mental health. Furthermore, a number of “bad” bacterial species found in the gut may contribute to higher levels of stress hormones.
2. Balance Hormones
One way that the gut-brain axis communicates is through the endocrine system, which secretes hormones into our bloodstream. Hormones have an enormous influence on nearly every aspect of human function, including growth and development, metabolism, reproduction, sleep, and mood—all of which have direct or indirect impact on mental health. Various nutrients, toxins, and antigens present in our gut can activate the release of hormones that affect physical and mental health. Furthermore, a number of “bad” bacterial species found in the gut may contribute to higher levels of stress hormones. By balancing the gut flora, the consumption of probiotics can actually promote mental health and decrease stress.
3. Boost Your Immune System
Pathogens such as viruses, bacteria, or other microorganism that causes disease activate the body’s immune system and increase inflammation levels, which in turn can increase depressive symptoms. Our gut contains the majority of immune cells in our bodies. Healthy gut flora boosts our immune system function by suppressing the growth of “bad bacteria” and reducing the risk of infection with pathogens we ingest with food. The improvement of immune function and lessening of inflammation in the gut can contribute to improvement in mental health.
4. Reduce Inflammation
Probiotics can contribute to reduced inflammation in the gut, and inflammation has been associated with certain mental disorders, especially anxiety and depression. An out-of-balance gut is associated with higher levels of inflammatory molecules called cytokines in the blood. Studies show that probiotics can alter the microbial composition of the gut to decrease cytokine production, benefit gut-brain signaling, and improve the integrity of the gut wall all of which result in lower inflammation and thus benefit our brain and mental health.