A two-way communication system between the brain and gut influences our mental health and digestive function. Evidence shows the importance of diet in the treatment and prevention of depression and anxiety. Conversely stress and anxiety can contribute to digestive problems.
The gut microbiome plays a key role in this gut brain communication. It consists of a range of microorganisms that live in the digestive tract and are essential for extracting nutrients from food and stimulating the production of short chain fatty acids (SCFAs), vitamins and neurotransmitters.
The main pathways of communication between the brain and gut are neural via the vagus nerve, the immune system, endocrine cells in the gut epithelium and release of small signalling molecules including SCFAs and neurotransmitters such as serotonin.
Studies have shown that the gut microbiome is altered in depression and anxiety with changes in the number and species of different microorganisms. The microbiome is very responsive to diet. Diets high in whole plant foods support microbial diversity whereas those high in refined carbohydrates and ultra-processed food have less microbial diversity and more bacteria species associated with inflammation.
While the gut microbiome may be a key mechanism through which diet can affect mood other ways in which food can influence the gut brain axis include changes in inflammatory markers, increase or decrease in oxidative stress, changes in tryptophan metabolism and serotonin production, and production of brain-derived neurotrophic factor (BDNF) which is involved in growth and maintenance of nerve cells improving plasticity in the brain.
There is growing evidence that a healthy diet can reduce the risk or be used to treat symptoms of depression. The Mediterranean diet significantly reduces the development of depression and reduces depressive symptoms in people diagnosed with depression.
Components of a healthy diet that supports gut health and the gut microbiome include dietary fibre which can be found in fruit, vegetables, whole grains, legumes, nuts and seeds. Fermented food such as yoghurt, kefir and sauerkraut which provide live microorganism and microbial metabolites, and omega 3 fatty acids found in olive oil, oily fish, nuts and seeds.
Plant phytochemicals play an important role in maintaining the gut microbiome and influencing mood. Key compounds are polyphenols which can be found in pigmented fruits and vegetable such as blueberries, red grapes, red onions, sweet potatoes and dark leaf greens. Herbs rich in polyphenols include oregano, thyme, turmeric, ginger and green tea.
Herbal treatments that contain phytochemicals that can influence mood by regulating the microbiome gut brain axis have been termed ‘Phyto-Psychobiotics’ (Mills, 2025). Berberine found in Oregon grape and barberry activates the microbiome-gut brain axis influencing BDNF and neurotransmitter levels in the hippocampus region of the brain and alleviating depressive symptoms. Other herbs that may influence mood via action on the gut microbiome include ginkgo, liquorice, rosemary and schisandra.
Integrating a healthy whole food plant-based diet with herbal remedies to support the gut microbiome and the gut brain axis provides a valuable mechanism for improving mental health and preventing or reducing the symptoms of depression.
Sources
Simon Mills, (2025) ‘Mills and Bone get restless and worn-down part two’. Mills and Bone Academy www.millsandbone academy.com
Maya Oakley, (2026) Nurturing the gut microbiome: nutrition and herbal approaches. Herbal Reality www.herbalreality.com
Heidi Staudacher et al (2023) Diet interventions for anxiety and depression. In Nutritional Psychiatry Ed Ted Dinan pg 72-100 Cambridge University Press
The gut microbiome plays a key role in this gut brain communication. It consists of a range of microorganisms that live in the digestive tract and are essential for extracting nutrients from food and stimulating the production of short chain fatty acids (SCFAs), vitamins and neurotransmitters.
The main pathways of communication between the brain and gut are neural via the vagus nerve, the immune system, endocrine cells in the gut epithelium and release of small signalling molecules including SCFAs and neurotransmitters such as serotonin.
Studies have shown that the gut microbiome is altered in depression and anxiety with changes in the number and species of different microorganisms. The microbiome is very responsive to diet. Diets high in whole plant foods support microbial diversity whereas those high in refined carbohydrates and ultra-processed food have less microbial diversity and more bacteria species associated with inflammation.
While the gut microbiome may be a key mechanism through which diet can affect mood other ways in which food can influence the gut brain axis include changes in inflammatory markers, increase or decrease in oxidative stress, changes in tryptophan metabolism and serotonin production, and production of brain-derived neurotrophic factor (BDNF) which is involved in growth and maintenance of nerve cells improving plasticity in the brain.
There is growing evidence that a healthy diet can reduce the risk or be used to treat symptoms of depression. The Mediterranean diet significantly reduces the development of depression and reduces depressive symptoms in people diagnosed with depression.
Components of a healthy diet that supports gut health and the gut microbiome include dietary fibre which can be found in fruit, vegetables, whole grains, legumes, nuts and seeds. Fermented food such as yoghurt, kefir and sauerkraut which provide live microorganism and microbial metabolites, and omega 3 fatty acids found in olive oil, oily fish, nuts and seeds.
Plant phytochemicals play an important role in maintaining the gut microbiome and influencing mood. Key compounds are polyphenols which can be found in pigmented fruits and vegetable such as blueberries, red grapes, red onions, sweet potatoes and dark leaf greens. Herbs rich in polyphenols include oregano, thyme, turmeric, ginger and green tea.
Herbal treatments that contain phytochemicals that can influence mood by regulating the microbiome gut brain axis have been termed ‘Phyto-Psychobiotics’ (Mills, 2025). Berberine found in Oregon grape and barberry activates the microbiome-gut brain axis influencing BDNF and neurotransmitter levels in the hippocampus region of the brain and alleviating depressive symptoms. Other herbs that may influence mood via action on the gut microbiome include ginkgo, liquorice, rosemary and schisandra.
Integrating a healthy whole food plant-based diet with herbal remedies to support the gut microbiome and the gut brain axis provides a valuable mechanism for improving mental health and preventing or reducing the symptoms of depression.
Sources
Simon Mills, (2025) ‘Mills and Bone get restless and worn-down part two’. Mills and Bone Academy www.millsandbone academy.com
Maya Oakley, (2026) Nurturing the gut microbiome: nutrition and herbal approaches. Herbal Reality www.herbalreality.com
Heidi Staudacher et al (2023) Diet interventions for anxiety and depression. In Nutritional Psychiatry Ed Ted Dinan pg 72-100 Cambridge University Press
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