Almost everyone has experienced mood changes that seem utterly inexplicable. Could the activities in our gut cause such mood changes? If so, how? What specific changes in our gut could influence our mood? What can we do to influence our gut health, to maximise our mood health, and our mental health?
How your gut-brain connection impacts your mood
Have you ever felt moody, anxious, or depressed for no apparent reason? Almost certainly. Your mood changes might not be as random as they seem. An increasingly large field of research can now demonstrate that there is a complex connection between your gut and your brain. And that connection plays a substantial role in your mental well-being.
Your gut-brain connection is a two-way street
We now know that our gut and brain are engaged in constant bidirectional communication. Our gut influences our brain and vice versa. Together they form a closed feedback system. While we are still pretty clueless about how the system works, we think we know the key components.
Your gut microbiome
Your microbiome, a vast community of microorganisms residing in your gut, plays a crucial role in our brain functioning. These tiny organisms produce neurotransmitters, such as serotonin and dopamine, which are essential for regulating mood, emotions, and cognitive functions.
What specific changes in our microbiome can influence our mood?
Decreases in the variety of gut bacteria seem to be involved in causing mood disorders, including depression and anxiety.
An imbalance between beneficial and harmful bacteria, causing an excess of harmful bacteria, can disrupt our gut’s delicate ecosystem and negatively impact our mental health.
Short-chain fatty acids (SCFAs) are produced by beneficial gut bacteria, have anti-inflammatory properties, and can positively influence mood.
As mentioned previously, gut bacteria produce neurotransmitters that directly influence mood.
Chronic inflammation, often caused or worsened by gut health problems, is a likely cause of various mental health disorders.
The body’s response to stress releases cortisol and adrenaline, which can negatively impact gut health, leading to mood fluctuations.
Which gut bacteria have the greatest impact on mood?
While the exact mechanisms by which gut impacts mood are still being researched, several gut bacteria have been identified as potentially playing a significant role in mood regulation. Here is a summary of what little we know about the workings and mood impact of particular bacteria.
- Bifidobacterium are considered to be beneficial probiotics, helping to maintain a healthy gut microbiome by competing with harmful bacteria. Bifidobacterium produce short-chain fatty acids (SCFAs), such as butyrate, which have anti-inflammatory properties. SCFAs can help regulate the immune system and reduce inflammation, which seems to contribute to mood disorders like depression and anxiety.
- Lactobacillus helps balance the gut microbiome and produces lactic acid that inhibits the growth of harmful bacteria. Lactobacillus produces gamma-aminobutyric acid (GABA), a neurotransmitter that has calming and anxiety- and stress-reducing effects.
- Faecalibacterium, as with Bifidobacterium, also produces SCFAs, particularly butyrate, which is a key energy source for our colon cells. Faecalibacterium helps to reduce inflammation, improves gut barrier function, and is known to positively improve mood.
- Akkermansia muciniphila is essential for maintaining the integrity of the gut lining. A healthy gut lining is, in turn, essential for proper digestion and absorption of nutrients. It also helps prevent the transmission of harmful substances into the bloodstream, which can contribute to inflammation and negatively impact mood. By keeping our gut lining healthy, Akkermansia muciniphila reduces inflammation and improves mood.
- Bacteroides are one of the most abundant genera (category of species) in the human gut. So far, hundreds of species have been identified. They are essential for breaking down complex carbohydrates and polysaccharides. Bacteroides also produce SCFAs, which, as we previously noted, have beneficial effects on gut health and overall well-being.
- Prevotella perform a similar function to Bacteroides. Prevotella are involved in the breakdown of complex carbohydrates, especially those found in plant-based diets. They can also contribute to SCFA production.
- Escherichia. While some Escherichia species are harmless and even beneficial, others, like E. coli, can be pathogenic and cause foodborne illness. However, most Escherichia strains in the gut are harmless.
- Enterococcus can be both beneficial and potentially harmful. Some species are involved in digestion and nutrient absorption, while others can cause infections, especially in healthcare settings.
- Clostridium is a diverse genus that includes both beneficial and harmful species. Some Clostridium species can produce toxins that cause diseases, while others are involved in the breakdown of complex carbohydrates and the production of SCFAs.
- Ruminococcus species are important for the breakdown of complex carbohydrates, including fibre. They can also produce SCFAs, with all their known mood benefits.
- Roseburia are similar to Ruminococcus in that Roseburia is involved in the breakdown of complex carbohydrates and the production of SCFAs.
Those are just a few examples of the bacteria that are known to have an impact on mood.
The relationship between gut bacteria and mood is so complex that we are nowhere near understanding how it works. Not least because the exact number of distinct bacterial species residing in the human gut biome is currently unknown. There may be tens of thousands, if not millions, of different species performing a function in our gut. As research progresses, new species are constantly being discovered. That adds to the complexity; with each new species discovered, we become aware that we are unaware of how it interacts with all the other species and all the body’s systems.
Individual differences in our gut microbiome also complicate matters. The diversity of the microbiome can vary significantly between individuals, for reasons that we are nowhere close to understanding, influenced by factors such as diet, lifestyle, and genetics.
How can you nurture your gut-brain connection?
Although we are vastly ignorant of the workings of our gut microbiome and how it interfaces with all other bodily systems, there are some high-level actions that are known to be well-being beneficial. Here they are:
- Adopting a diet rich in fibre, fruits, vegetables, and whole grains can create the best conditions for a healthy microbiome. Probiotic-rich foods like yoghurt and fermented vegetables can also be beneficial. Prebiotics, too, are helpful. They are dietary fibres that feed beneficial gut bacteria. They can be found in foods like onions, garlic, and asparagus.
- Stress management. Prolonged or chronic stress can negatively impact gut health. Practicing stress reduction techniques like meditation, yoga, or deep breathing can help.
- Regular physical exercise and activity can improve gut motility and reduce inflammation.
- Sufficient sleep is essential for overall health, including mental well-being. Aim for between seven and nine hours of quality sleep each night.
- Minimise alcohol and processed food consumption. Excessive alcohol consumption and a diet high in processed foods is known to harm gut health.
We know very little about how our gut health impacts our mental health. But we know that it does have a huge impact. We also know that eating a healthy diet, and avoiding things that damage our gut microbiome is good for our immune health, and for our mental health and mood.
Professor Nigel MacLennan runs the performance coaching practice PsyPerform.
