The connection between the gut, heart and brain: a detailed investigation

The gut-heart-brain axis is an interdisciplinary field of research that investigates the interconnectedness of these three vital organ systems. The health of one of these organs has a significant impact on the others, and the mechanism behind this interaction is a complex interplay of chemical, neural and immunological signals. The connection clearly shows that the body is an integrated whole in which all parts are closely interconnected.

1. the intestine as the centre of the body: the "second brain"

The intestine is often referred to as the "second brain" as it has its own nervous system, the enteric nervous system (ENS). This network comprises around 100 million neurones - more than the spinal cord - and can function independently of the brain. In addition, there is the intestinal microbiome, a huge community of microorganisms that live in the digestive tract.

The gut microbiome and its importance

The microbiome is not only responsible for digestion, but is also a key player in the regulation of the immune system, the production of neurotransmitters and the control of inflammation. Billions of microorganisms, including bacteria, fungi and viruses, form an ecosystem that influences the entire body.

• Neurotransmitter productionAbout 90 % of the body's serotonin, known as the happiness hormone, is produced in the gut. Serotonin is not only important for well-being and emotional stability, but also plays a role in regulating the heart rate and digestion.
• Microbiome and immune systemThe majority of the body's immune cells are found in the gut. The microbiome helps to modulate the immune response and maintain a balanced immunity. A disturbed microbiome can lead to overactivation of the immune system and chronic inflammation.

The connection between the gut and the brain

The vagus nerve plays a central role in communication between the gut and the brain. This tenth cranial nerve extends from the brain stem to the abdominal cavity and continuously transmits signals in both directions. In the event of disorders in the gut, such as dysbiosis or inflammation, signals are transmitted to the brain via the vagus nerve, which can lead to mood disorders, depression or even cognitive impairment.

Exemplary statement:

Dr Michael Gershon, the founder of the term "second brain", explains:

"The gut has remarkable autonomy and an enormous amount of neuronal resources. The enteric nervous system has the potential to influence our emotions and shape the health of the brain."

2. the connection between the gut and the heart: inflammatory processes as a key factor

The gut and the heart are connected via the systemic regulation of inflammation. A disrupted gut barrier, also known as "leaky gut", allows harmful bacteria and toxins to enter the bloodstream. These toxins can trigger an inflammatory response throughout the body, which also affects heart health.

TMAO - The influence of the microbiome on the heart

Certain intestinal bacteria produce trimethylamine (TMA), which is converted into trimethylamine N-oxide (TMAO) in the liver. Studies show that increased TMAO levels are associated with a higher risk of heart attacks, strokes and atherosclerosis.

• Atherosclerosis promotionTMAO promotes the accumulation of cholesterol in the arterial walls, making it more difficult to remove. This leads to the formation of plaques and thus to atherosclerosis.
• MyocarditisEndotoxins that enter the bloodstream through a disturbed intestinal barrier can cause myocarditis.

Exemplary statement:

Dr Stanley Hazen, leading researcher in this field, explains:

"The microbiome has a profound influence on the cardiovascular system, and the targeted modulation of gut bacteria could be a promising way to prevent cardiovascular disease."

3. the gut-brain axis: the role of the microbiome in the brain

The connection between the gut and the brain is mediated via the nervous system (especially the vagus nerve), the endocrine system and the immune system. Dysbiosis can disrupt the balance of neurotransmitters produced in the gut. This can increase the risk of neurological and psychiatric disorders.

Influence of the microbiome on mental health

• Depression and anxiety disordersResearchers have discovered that a disruption in the microbiome is associated with depression and anxiety. Different strains of bacteria produce neurotransmitters such as gamma-aminobutyric acid (GABA) and serotonin, which influence emotional well-being.
• Neurodegenerative diseasesDysbiosis in the gut could be a risk factor for neurodegenerative diseases such as Parkinson's or Alzheimer's. Researchers suspect that inflammatory cytokines enter the brain through an impaired blood-brain barrier and cause damage there.

Exemplary statement:

Dr John Cryan, a leading expert in the field of microbiome research, emphasises:

"The microbiome has a profound influence on our brain and our psyche. Research on the gut-brain axis shows us that we can potentially influence mental health by manipulating the microbiome."

4. the heart-brain connection: The interplay between stress, emotions and heart health

The heart and brain communicate via the autonomic nervous system. Stress and emotions play a crucial role in heart health. Chronic stress activates the hypothalamic-pituitary-adrenal axis (HPA axis) and increases the release of cortisol, the so-called stress hormone.

Stress and heart health

• Cardiac arrhythmia and high blood pressureChronic stress leads to a permanent activation of the sympathetic nervous system (part of the autonomic nervous system), which can lead to increased blood pressure, tachycardia and even cardiac arrhythmia.
• PsychocardiologyThis field of research investigates the effects of psychological factors on heart health. Depression and anxiety disorders have been shown to increase the risk of heart attacks. At the same time, heart disease, such as coronary heart disease, can promote depressive moods.

Exemplary statement:

Dr Dean Ornish, pioneer in heart health research, explains:

"Love and intimacy are powerful remedies. What really nourishes the heart and brain is not just medication or surgery, but a life of connection - to others, to oneself and to a higher reality."

5. practical examples of integrative health

Research on the gut-heart-brain axis shows how crucial a healthy lifestyle is to promote the interactions between these three organ systems.

Mediterranean diet and its influence on the microbiome

The Mediterranean diet, which is rich in vegetables, fruit, nuts, wholemeal products, healthy fats (such as olive oil) and fish, has proven to be very beneficial for the microbiome. It promotes the proliferation of beneficial bacteria that produce short-chain fatty acids, which have an anti-inflammatory effect and support a healthy intestinal barrier.

Probiotics and prebiotics

• ProbioticsBacterial strains such as Lactobacillus and Bifidobacterium promote healthy intestinal flora and can alleviate depression, as has been proven in clinical studies.
• PrebioticsPrebiotic fibres such as inulin are nutrients for beneficial bacteria and promote the production of short-chain fatty acids, which in turn have positive effects on the heart and brain.

Stress management techniques

• Yoga and meditationYoga and meditation are proven methods for reducing stress. They promote the activation of the parasympathetic nervous system and thus the "rest-and-digest" mode, which has a relaxing effect on the heart and calms the HPA axis.
• Vagus nerve stimulationConscious stimulation of the vagus nerve - for example through breathing exercises, meditation or exposure to cold - has a positive effect on heart rate variability and helps to improve gut-brain communication.

Exemplary statement:

Dr Elisabeth Blackburn, Nobel Prize winner for her research on telomeres, says:

"What keeps our cells healthy is not only a healthy diet and exercise, but also the reduction of stress. Understanding the microbiome and its connection to the brain and heart could be the future of preventive medicine."

6 Conclusion: A holistic understanding of the gut-heart-brain axis

The gut-heart-brain axis illustrates how closely the organ systems are interlinked and how much they influence each other. A healthy lifestyle that promotes gut health can significantly reduce the risk of cardiovascular and neurological diseases.

Important scientific statements summarised:

1. "The microbiome is a key factor in heart health. A healthy microbiota can reduce systemic inflammation and minimise the risk of cardiovascular disease." - Dr Stanley Hazen
2. "The gut-brain axis is crucial for our mental health. There is a bidirectional communication that we can positively influence by taking care of our microbiome." - Dr John Cryan
3. "Stress reduction is a key to brain and heart health. The vagus nerve plays a central role in controlling these organ systems." - Dr Dean Ornish

Science has shown us that we can promote our physical and mental health by consciously eating, exercising, reducing stress and looking after our microbiome. This holistic approach not only contributes to a healthier body, but also to a more balanced mind and a happier life.