The significance of the gut in influencing health cannot be overstated, with a staggering 90% of diseases believed to originate in this intricate system. Today, our understanding has elevated the gut, along with its microbiome, to the status of an organ in its own right. With wow factors like these, we really can’t afford to ignore this overlooked “body system” as if it is somehow irrelevant to how we feel.

I’m sure you’ve heard of the “gut-brain” link? And if you haven’t where have you been hiding this past year?! So just what is the gut microbiome? How does it influence our mental health? In what other ways does the gut influence our wellbeing? And what can we do to ensure it’s working for us and not against us?

A little overview of the gut microbiome. It is a diverse ecosystem of micro-organisms mainly bacteria, but also viruses, fungi and even parasites (they’re not all considered bad). It’s a mutually beneficial symbiotic relationship which means if we take care of them they will take care of us.  We each have approx. 100 trillion microbes equivalent to ten times the number of cells in our body. You have more microbes in your gut than there are people in the World!

When everything is in balance, there should be harmony supporting our health both mental and physical. But too often chaos can occur resulting in an overgrowth of pathogenic micro-organisms leading to an imbalance known as dysbiosis. This in turn can affect our mental and physical health.

The Gut-Brain Connection

There is a separate nervous system connecting the gut directly with the brain called the enteric nervous system. There is a two-way flow of information – each influencing the other. That feeling of butterflies in your stomach? Or feeling sick before an important event? These really do happen and show the enteric nervous system in operation.

We know that large emotional triggers can cause upset in the gut and the research now also shows that this happens the other way round. The gut is influencing our mind and behaviour. This explains why people who experience IBS and bowel irregularity may also experience depression and anxiety. With children, research has shown that children with ADHD often have gut disorders like IBS too.


The gut and brain are communicating through a series of neurotransmitters- chemicals that act like hormones sending communications.

Serotonin is a well-known neurotransmitter associated with calmness and happiness. It is also linked to improved sleep and feeling less stressed. 90% of all the serotonin in the body is produced in the gut – far more than in the brain. GABA is another neurotransmitter that helps control feelings of anxiety and fear. The production of these neurotransmitters is directly related to the presence of beneficial gut bacteria. The deficiency of certain bacteria has been shown in research to lead to increased levels of depression and/or anxiety.


We have a delicate balance between beneficial bacteria (that support our health) and pathogenic bacteria that can damage it- dysbiosis.

A lack of beneficial gut microbiota diversity plays a role in the development of depression. Antibiotic use (which depletes beneficial bacteria) may increase the risk of depression Certain strains of pathogenic bacteria shed toxins that enhance the stress response. Pathogenic bacteria create toxins that damage the gut lining, creating inflammation which has been shown to enhance depression and anxiety.

So how do we support our gut microbiome and brain health?

Polyphenol-rich foods: Polyphenols are plant compounds that help the growth of beneficial bacteria and have been linked to improved cognition too. Pomegranate, cranberries, plums, berries, flaxseed, green tea, olive oil and coffee (in moderation) all contain polyphenols.

Prebiotic-like foods: These feed the beneficial bacteria to support their abundance and diversity. Leeks, onions, garlic, fennel, oats, almonds, brown rice, blackcurrants, green tea, very dark chocolate (in moderation!).

Colonic foods are fermented by gut bacteria to produce short chain fatty acids (SCFAs) and these promote the growth of further beneficial bacteria. Such as psyllium husk, slippery elm and pectin. One of my favourite gut nourishing foods for depleted individuals is stewed apple (skinned, no sugar, with cinnamon). Apples are a rich source of pectin so eat a little every day.

High-fibre foods: Whole grains like brown rice (and avoiding gluten grains like wheat and rye), nuts, seeds, pulses, fruit and vegetables all contain soluble and insoluble fibre that help to keep transit time regular, helps elimination of toxins and lowers the risk of inflammatory conditions. Aim to increase your daily vegetable intake and have as much diversity and colour as possible.

Fermented foods: We are more familiar with these functional foods now from yogurt, kefir, to sauerkraut, kimchi and kombucha. The fermentation process increases levels of beneficial bacteria particularly lactic acid bacteria. They have been shown to beneficially enhance brain activity.

Eating these foods should become a way of life. The hidden community of bacteria is driving many aspects of our mental health. Do all you can to keep your brain healthy by taking care of your microbiome.

Caroline Peyton
Nutritional Therapist & Naturopath at Peyton Principles | Website | + posts

Caroline Peyton of Peyton’s Principles is a qualified nutritional therapist and naturopath with clinics in Wiltshire, the Cotswolds and online. She has a specialism in gut health and is often asked to support teams and c-suite executives around nutrition and performance in the workplace. She runs retreats for women of all ages to help them consider nutrition in their every day lives, helping them with recipes and around small changes they can make on a daily basis to improve their wellbeing through nutrition. She is a regular media commentator offering hints and tips around all aspects of nutrition, wellbeing and how nutrition can help with all kinds of conditions including diabetes, menopause, IBS and many others.