Many people believe that they are entirely in control of their minds. But recent research has revealed that the trillions of microorganisms living in our gut, collectively known as the gut microbiome, have a complex relationship with our brain which can influence our mind, including our mood, behaviour, and cognitive function.
The gut-brain axis, a communication pathway between the gut and the brain, plays a significant role in regulating our physiological and psychological responses. This pathway involves the release of chemical messengers, such as hormones and neurotransmitters, that can influence the brain's activity and vice versa. For instance, gut bacteria can produce the neurotransmitter serotonin, which is known to regulate our mood, appetite, and sleep. Some gut bacteria produce short-chain fatty acids that can reduce inflammation, protect the gut lining, and influence the activity of immune cells. Another way the gut communicates with the brain is via the vagus nerve, "which acts as a superfast 'internet connection' between our brain and internal organs."
Probiotics may help alleviate anxiety and depression
Studies have found a link between the gut microbiome and mental health conditions such as depression, anxiety, and autism. People with depression have a distinct gut microbiome composition, with lower levels of beneficial bacteria such as Bifidobacterium and Lactobacillus. Supplementing with probiotics containing Lactobacillus and Bifidobacterium can alleviate symptoms of anxiety and depression in some individuals. A recent study found that supplementing with probiotics for four weeks significantly reduced depressive symptoms.
Gut microbiome and cognitive skills
Antibiotics disrupt the gut microbiome, which may affect cognitive function. A recent study with nurses found that "those who had used antibiotics for long periods of time (more than two months) scored lower on cognitive tests of learning, working memory and attention tasks than those who hadn't taken such medication." And their cognition was still slightly lower seven years later.
Environmental factors such as diet, stress, and antibiotics can influence the gut microbiome, affecting the gut-brain axis. A diet high in fibre and fermented foods can promote the growth of beneficial bacteria and improve mental health outcomes. On the other hand, chronic stress can disrupt the gut microbiome and exacerbate mental health conditions.
You can change your microbiota
Mental health conditions are often associated with changes in the microbiota, characterized by a reduction in certain bacteria that produce short-chain fatty acids such as butyrate, which is believed to improve brain function.
"The good news is that you can change your microbiota, while there's not a whole lot you can do to change your genetics." "The fact that you can modify your microbiota potentially gives you agency over your own health outcomes. Pro- and prebiotic supplements, simple dietary changes, such as eating more fermented foods and fibre – and even, perhaps, meditation – can help alter our microbiota in ways that benefit our minds." Scientists have coined the term "psychobiotics" for microbiota-based interventions that benefit the human brain.