Study of gut microbiota may benefit our mental health

In the last two years, the world's interest in healthcare science has rocketed for obvious reasons. The novel coronavirus pandemic has shown us just how maneuverable medical research can be in a crisis, spurred on to progress at breakneck speed. Vaccines, however, are just one of many topics to which scientists are dedicating their careers. One area that has caused great excitement during the last 15 years is human gut microbiota.

Studying the microscopic organisms within our bodies has been overlooked for decades, but a growing weight of research suggests that these bacteria impact the majority of our bodily functions, even significantly controlling our moods, psychological behaviors and mental states. The field has fast become an area attracting a significant growing community of Chinese scientists, hoping to gain new insights into treating the human body.

Microbiota in the gut especially seem to influence brain biochemistry, however the specific causal links behind this remain unclear. Chinese researchers are now aware that the intestines communicate with the brain, and the status of gut bacteria can affect stress-related disorders such as anxiety and depression. What some researchers have playfully dubbed a "collective unconscious" may be affecting our behavior much more than we once thought, controlling our cognitive function and even fundamental behavior patterns.

This is not surprising, when one considers the fact that a sizable minority of cells that make up the human body are not human cells, but a mass population of trillions of relatively harmless bacteria, fungi and viruses. How they interact with us specifically, however, is still mainly a mystery, with microbiota researchers such as Yuan Jin, from the Capital Institute of Pediatrics Beijing, describing the puzzle as a black box. Such researchers state that they can identify when patients have an imbalance of microorganisms in their bodies, but are none the wiser when it comes to identifying which species are responsible for certain conditions.

However, this is starting to change. A study published this year in conjunction with Jiangnan University has found noticeable antidepressant effects using a psychobiotic strain of gut bacteria called Bifidobacterium breve CCFM1025.The molecular mechanism of action remains unclear, however this is also true for many existing drugs currently used for mental health in public health systems. The strain is being investigated for its genetic features, and there is potential to use them in so-called "psychobiotics", where consuming the microorganisms may in the future be a way of modulating our mental health.

Promising in animal studies so far, it could be a breakthrough in an area of mental health dominated by side-effect-ridden alternatives. Typically, natural probiotics already in mainstream use for digestive issues have mild side effects in contrast, and are well tolerated in our guts, which have evolved to host and coexist with such organisms throughout our evolution.

Ask a neuroscientist just 10 years ago whether gut bacteria had any effect on the brain's mood, and you would have been met with disbelief. However, many scientists now suspect the possibility that such bacteria are even influencing gene expression in our brains, reprogramming how our minds function and influencing our behaviors, to a previously unprecedented degree.

Aside from the exciting prospects that this holds for how we understand and treat our minds, this novel field may also challenge the very notion of how we consider our identities as singular entities. We are, after all, multicellular arrangements made up from the sum of trillions of cells. The fact that trillions more are residing within us, and influencing our lives more than we think, is a thought to behold.

Barry He is a London-based columnist for China Daily.