Research on the complex interaction between our gut microbiota and brain function supports the idea that well-being is much more than the sum of our physical and mental parts.
The English language is full of sayings that allude to an intimate connection between the brain and the body: a “heartbreaking sensation”; your ‘heart is in your throat’; not having ‘the stomach’ for something. And while many idioms are obscure in origin, those that speak to the interconnected nature of our body systems turn out to be based more on science than folklore.
Over the past decade, research has begun to show that the gut is extremely sophisticated and interdependent. It is governed by the enteric nervous system (ENS), a division of the autonomic nervous system, and it is estimated that there are more than 100 million neurons in the small intestine alone. Throughout the ENS, the number of neurons is second only to the brain, which has led the intestine to be called the “second brain” or “intestinal brain”.
If you consider the butterflies in your stomach before an important event, this brain-to-body signaling might not be all that surprising. But scientists are now showing that it’s not just a one-way street – the gut strongly influences brain function too, not just the other way around. “We’re starting to realize that bacteria can make things that can directly affect the brain,” says Gérard Eberl, director of immunology at the Institut Pasteur, a Paris-based nonprofit research foundation.
Eberl and neuroscientist Pierre-Marie Lledo, together with their teams, published A study in the journal Nature Communications in December 2020 which demonstrated the symbiotic relationship between gut health and mood. They found that changes in the microbiota of the mice as a result of chronic stress produced depressive behaviors. Then, when certain bacteria were reintroduced into the guts of the mice, the animals’ bad mood dissipated.
Scientists suggest that the gut strongly influences brain function. Image: Ben White
With depression affecting more than 264 million people around the world. And with the issue in the spotlight now more than ever due to the mental health strain caused by the pandemic, many are on the lookout for strategies to deal with it. But will taking a dose of probiotics with your morning porridge really make a difference?
As with most health tips, it is not as straightforward as that. But Eberl says there are encouraging studies, including his, that actually point to the impact of gut bacteria on brain function. For example, neurotransmitters such as adrenaline, norepinephrine or serotonin are simple molecules that can be built by intestinal bacteria, he explains. “There is not so much data yet, but … a lot [these small molecules] they go to the blood and many of them are going to reach the brain. “
So for some people, making an effort to restore the balance of “good” and “bad” bacteria in their gut could have an effect on mood. But health and wellness are dynamic concepts, and Eberl cautions that there are many different and complex factors that contribute to depression and mood.
Examining the gut-brain axis, as well as how lifestyle factors combine to influence health, is something Luna Irshaid has set out to address. She established The Good Mood Co last year, a UK-based startup backed by the UCL Innovation and Enterprise incubator program. The company focuses on three interrelated aspects of health: gut, brain and sleep, and offers plant-derived supplements to boost brain power and energy levels.
Good gut health has been linked to improved sleep. Image: Bruce Mars
This month the team launches a digital tool that will help their clients focus not only on what they put on their body, but will encourage them to spend 15 minutes a day in a ‘good mood’. Those 15 minutes could include reading positive news, taking deep breaths, or exercising. Reminders will be linked to subscribers’ calendars.
Irshaid describes herself as someone who burns the candle at both ends. He studied mechanical engineering and business finance at University College London and the London School of Economics, and went on to work in international foreign investment. But one day in her mid-20s, she woke up feeling totally drained. “I was supposed to be in the prime of my health and youth, and yet I was completely exhausted,” she says. Many of his friends felt the same.
After embarking on the search for a solution, he came across some surprising statistics. “About 74 percent of adults [reported feeling] overwhelmed. “Add to that the fact that 86 percent of adults reported having a gastrointestinal problem in the past year. [a 2016 figure], Y two-thirds has regularly interrupted sleep, and has a perfect triumvirate of poor health.
“The UK is a nation in distress and a nation in distress,” says Irshaid. “[We live this] High intensity lifestyle that simply unbalances the body and drains us of essential nutrients. And that really negatively affects people’s mood, health, personal life, and job performance. “
The solution? Eberl agrees with Irshaid that there is no magic formula. But it’s worth keeping an eye out for new research on the gut-brain axis as it continues to emerge. “It’s a very interesting research area,” he says, “it’s extremely complex.”
And taking probiotics definitely can’t hurt, he adds. “But they can only do so much. You can’t cure cancer with probiotics. “
Irshaid takes a pragmatic approach, with an eye to the importance of technology in the modern world. “[Health is] not just by taking a supplement or eating a yogurt from time to time, “he says. “It’s about having a comprehensive, multidimensional solution for the modern human being that is both physical and digital.”
Lead Image: Edu Lauton