Image for Linking the Microbiome, Diet, the Brain and Mental Health

*Pic: Medical, by Antonio Casas

Mounting evidence supports the concept that our gut is indeed the brain outside the brain, with continued exploration of the ‘gut-brain axis’ and relationships between the gut microbiome and brain function.

Research indicates there is ‘bidirectional communication between the central and enteric nervous system, linking emotional and cognitive centres of the brain with peripheral intestinal functions.’ [1] Microorganisms in the gut microbiome facilitate this process through a combination of hormonal, immunological and neurological linkages. [1]

It is not surprising to discover that alterations to the microbiome and certain gastroenterological conditions can affect pathological processes contributing to neurological and psychiatric conditions. There is an explosion of research examining the microbiomes of patients with diseases ranging from psychotic illnesses to eating disorders and dementia.

For example, one team of researchers describes an alteration in the gut microbiome in patients with Parkinsons Disease being a great decrease of the bacterium Prevotellaceae. Perhaps more interestingly is that constipation appears as a sign in these patients years before the onset of their Parkinsons Disease. [2] This demonstrates the importance of general gut health, intestinal complaints and linkages with other pathologies in the body.

Paying attention to the health of your gut could potentially affect and positively alter neurological and psychiatric conditions. In 2011 Nature published research that anxious mice fed Lactobacillus rhamnosus bacteria became ‘more chilled out’. This area of research has led to an interest in what is now termed ‘psychobiotics’ with the idea that purposely altering the microbiome with the addition of specific probiotics might be useful in treating psychiatric conditions and could potentially revolutionise psychiatric pharmacology. [4]

Your diet can influence your mental health in many ways. What you eat is important, but how much is also important. Restrictive diets can have a detrimental effect on neurotransmitters.

The neurotransmitter serotonin is manufactured in the body from an essential amino acid called tryptophan found in foods such as eggs, cheese, salmon, nuts and seeds.

Serotonin is responsible for mood and low levels have been associated with depression, suicide and aggression.

The neurotransmitter dopamine is produced from another essential amino acid tyrosine, which is also found in cheese, milk, turkey, lima beans, avocados, bananas and certain fish. Dopamine is responsible for many executive functions, motivation and arousal.

These neurotransmitters and others play a central role in the limbic system, the part of the brain regulating emotions, mood and memory.

As I mentioned in a previous article, Omega 3 fatty acids positively affect the limbic system and have been shown to play a role in regulating mood.

It is evident even the type of fat we consume in our diets as well as other foods can affect our emotional states.

In reality there are a myriad of nutritional requirements in the human diet that affects brain function. For example, the depletion of thiamine in alcoholism can lead to a confusional state known as Wernicke’s encephalopathy. Other nutritional deficiencies such as A, C, B12 and folate can lead to reversible dementia states. Iron deficiency can lead to anaemia severe enough that the brain becomes hypoxic resulting in a confusional state.

Vitamin D deficiency can cause people to feel low in mood. This is particularly important for our largely vitamin D deficient population in Tasmania. The importance of adequate nutrition cannot be underestimated.

In starvation states and states of extreme hunger, the body is lacking in the basic building blocks for creating neurotransmitters. Some of the behavioral and psychiatric changes associated with anorexia nervosa are now recognized as the pathophysiological effects of starvation. Experiments such as the famous Minnesota Starvation Experiment of 1950, examined starvation and its effects on human behavior. Participants experienced an increase in obsessional and violent behavior when starved for extended periods of time. [6]

It is easy to draw the conclusion that the gut microbiome has an impact on mental health, brain health and general health. It is important to eat a balanced diet from a neurotransmitter perspective. In medical management of conditions such as depression, eating disorders, anxiety, low mood, even problems with cognition, diet plays a role in holistic management and achieving best outcomes.

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*Dr Anonymous is known to the Editor