3 Steps to Support the Brain-Gut Axis for Better Digestive and Mental Health
As the brain and digestive system are tightly connected, supporting this axis (CNS/ENS connection) can improve neuropsychiatric and gastrointestinal health.
The development of the brain-gut axis concept is stunning in the literature. Scientists initially proposed it to understand how the gut affected brain function. However, later they discovered that this unique network worked in both directions. This crucial finding emphasizes the powerful links between neuropsychiatric and gastrointestinal disorders.
Neuropsychiatric disorders can affect various aspects of our mental health, like emotions, mood, behavior, cognition, and perception. Common disorders are depression, anxiety, bipolar, schizophrenia, autism, attention deficit, obsessive-compulsive, and post-traumatic stress disorders.
Gastrointestinal disorders (digestive) affect the digestive system and its organs responsible for breaking down food, absorbing nutrients, and eliminating waste. Common disorders are irritable bowel syndrome, inflammatory bowel disease, acid reflux, leaky gut, celiac disease, stomach ulcers and cancers, and colon cancer.
This report from NIH informed that 70 million people were affected by digestive diseases in the United States. The team of Dr. Magnus Simren (MD/Ph.D.) found that “Nearly 40% of Adults Suffer From a Functional Gastrointestinal Disorder based on a survey of 33 countries in 2020.”
The brain-gut axis is a complex and dynamic system. Scientists still have not fully understood it. However, many studies and over 54,000 reports give us valuable clues on this critical axis regulating gut and brain health.
This paper informs that “insights into the gut-brain crosstalk have revealed a complex communication system that ensures the proper maintenance of gastrointestinal homeostasis and is likely to have multiple effects on motivation and higher cognitive functions.”
As informed by this paper, “The brain-gut axis is not only anatomical, but extends to include endocrine, humoral, metabolic, and immune communication routes.
The autonomic nervous system, the HPA axis, and nerves within the gastrointestinal tract all link the gut and the brain, allowing the brain to influence intestinal activities, including the activity of functional immune effector cells, and the gut to influence mood, cognition, and mental health.”
In this article, I provide a high-level overview of the brain-gut axis, introduce the critical systems based on credible sources, and provide practical tips to regulate this system and prevent its dysregulation via healthy lifestyle habits and professional support.
An Overview of the Brain-Gut Axis
The brain-gut axis is a vital communication system connecting the central nervous system (the brain and spinal cord) with the enteric nervous system in the gut.
This paper states, “ The gut-brain axis consists of bidirectional communication between the central and the enteric nervous system, linking the emotional and cognitive centers of the brain with peripheral intestinal functions.”
The review paper summarizes the available evidence supporting these interactions' existence and the possible pathophysiological mechanisms involved. Researchers point out that recent advances in research have described the importance of gut microbiota in influencing these interactions.
This intricate network of neural, endocrine (hormonal), and immune signaling pathways ensures the equilibrium (balance) between these two systems and facilitates optimal bodily functioning.
The brain and gut are interdependent, and one’s well-being influences the other. Learning about the brain-gut axis is valuable in maintaining physical and mental health and preventing related diseases.
Disruptions of the brain-gut axis can lead to various health issues, including gastrointestinal disorders, mood disorders, and neurological conditions.
This paper states, “Disruptions in the gut-brain axis affect intestinal motility and secretion, contribute to visceral hypersensitivity, and lead to cellular alterations of the entero-endocrine and immune systems.”
Dysfunction of the enteric nervous system is associated with diabetes, some cancers, and inflammatory conditions of GI disorders like irritable bowel syndrome, inflammatory bowel disease, gastroparesis, and increased sensitivity to gut stimuli, leading to abdominal pain, bloating, and diarrhea or constipation.
Dysfunction of the central nervous system is associated with neurological and psychiatric disorders, including Alzheimer’s, Parkinson’s, MS, ALS, epilepsy, stroke, traumatic brain injury, autism, schizophrenia, depression, anxiety, and many others.
Understanding the mechanisms underlying the brain-gut axis is an active area of research that has the potential to lead to new treatments for a variety of health conditions.
The CNS and ENS work together to maintain balance and regulate various bodily functions, including digestion, immunity, and mood.
How Enteric and Central Nervous Systems Are Connected
The enteric nervous system (ENS) is a complex network of neurons that governs the function of the gastrointestinal (GI) tract. It consists of two main components, the myenteric plexus, and the submucosal plexus.
The myenteric and submucosal plexus are two critical nerve networks in the GI tract. The myenteric plexus regulates smooth muscle contraction and GI transit rate and receives sensory input from the gut.
The submucosal plexus regulates blood flow, secretion, and absorption and receives sensory input from the gut. Both plexuses communicate with smooth muscle cells and glands through excitatory and inhibitory neurotransmitters.
The central nervous system (CNS) comprises the brain and spinal cord, responsible for processing and transmitting information throughout the body. The CNS serves as the control center for the body’s actions and responses to external stimuli.
The ENS is connected to the central nervous system (CNS) via the vagus nerve and sympathetic and parasympathetic nerves sending information bidirectionally between the brain and the gut.
The vagus nerve provides input to the ENS and modulates its function, while the sympathetic and parasympathetic nerves influence GI function through their effects on the ENS.
The CNS and ENS are closely connected and work together to regulate various bodily functions. The CNS is responsible for receiving and processing information from sensory organs and responding with appropriate actions.
The ENS controls the function of the gastrointestinal tract. It is called the “second brain” due to its ability to function autonomously. The ENS is capable of independent decision-making and can modulate the activity of the CNS.
For example, gut microbes can produce neurotransmitters such as serotonin, influencing mood and behavior. Gut bacteria can also activate the immune system and promote the release of cytokines, which can impact CNS function and behavior.
Overview of 3 Theories Shedding Light on the Brain-Gut Axis
There are several theories related to the brain-gut axis. The three prominent ones with multiple studies are related to the gut microbiome, stress, and inflammation. I provide a very high-level overview of them.
1 — Microbiome and Gut Dysbiosis Theory
According to this theory, the microbiome can influence the production of neurotransmitters, such as serotonin and dopamine, which are involved in regulating mood and behavior.
Studies indicate that disruptions to the gut microbiome, such as antibiotic use or junk food diet, can alter behavior and emotional processing.
Gut dysbiosis refers to an imbalance in the composition and function of the microbial community in the gut. A decrease in beneficial bacteria and an overgrowth of harmful bacteria, fungi, or viruses may result in an altered microbiome.
This imbalance can lead to various health problems, including chronic inflammation, immune dysfunction, metabolic disorders, and gastrointestinal symptoms.
Gut dysbiosis can be caused by various factors, like excess antibiotics use, a diet high in processed foods, oxidative stress, chronic inflammation, and environmental toxins.
2 — Inflammation Theory
This theory informs that the gut is a significant site of inflammation. Inflammation in the gut can impact the brain-gut axis.
Chronic inflammation has been linked to various neurological and mental health disorders. Inflammation can impact the brain-gut axis through changes in neurotransmitter synthesis and immune cell activation.
The enteric nervous system (ENS) is vital in regulating the immune system and inflammation in the gut. The ENS can produce and release cytokines, stimulating or inhibiting immune cells in the gut. Additionally, the ENS can respond to immune cells' cytokine and regulate GI function accordingly.
2 — Stress Theory
This theory proposes that stress can impact the brain-gut axis, leading to changes in gut motility, inflammation, and the release of stress hormones altering microbiome colonies.
From a stress perspective, the brain-gut axis is also connected with the HPA axis I introduced in a previous article as an intervention to lower chronic stress.
Stress-induced dysbiosis in the gut can impact the brain-gut axis, leading to a vicious cycle of stress and gut dysregulation, increasing the pressure on the enteric nervous system.
3 Practical Steps and Valuable Tips to Prevent Dysregulation of the Brain-Gut Axis
Many factors can dysregulate the brain-gut axis. In this section, I cover them under three headings highlighting the importance of healthy lifestyle habits as preventative measures. However, those with underlying gut and mental health issues must obtain timely professional support.
1 — Prevent the gut and the brain from toxins and pathogens.
An essential aspect of maintaining a healthy brain-gut axis is the avoidance of toxins and pathogens that can lead to dysregulation.
Toxins (heavy metals, pesticides, and environmental chemicals) can enter the body through contaminated food, water, and air. Once inside, they can cause damage to the gut lining and disrupt the balance of the gut microbiota, leading to inflammation and impaired gut function.
To avoid these toxins, we might choose healthy foods, filter drinking water and air, and minimize exposure to environmental toxins.
Pathogens (bacteria, viruses, parasites, fungi) can disrupt the gut microbiota and lead to inflammation and impaired gut function.
To avoid these pathogens, we may practice good hygiene, like washing hands regularly, cooking food thoroughly, and avoiding contact with contaminated surfaces and people with contaminating diseases.
Smoking can negatively affect gut and brain health by disrupting the balance of beneficial bacteria and increasing inflammation in the gut and the brain. Avoiding smoking can improve gut health and the communication between the brain and the gut.
Excessive alcohol consumption can disrupt the balance of beneficial bacteria in the gut, reducing gut health. It can negatively affect the brain and the communication between the brain and the gut. Limiting alcohol consumption can improve gut health and the communication between the brain and the gut.
High sugar intake impacts gut health as it can increase inflammation in the gut. Too much sugar can negatively affect the brain and the communication between the brain and the gut. Reducing sugar intake is critical for gut and brain health.
Antibiotics can disrupt the gut microbiome and negatively impact the brain-gut axis. Whenever possible, we must avoid unnecessary antibiotics, and with support from professionals, we may supplement with probiotics and prebiotics during and after antibiotic treatment to help restore healthy gut microbiota.
2 — Eat healthy foods and stay hydrated.
Eating whole foods and refraining from junk foods can improve gut health and prevent dysregulation of the brain-gut axis. Brain health is dependent on gut health.
Junk foods can harm the brain-gut axis. Consuming in excess can cause dysregulation of the gut microbiota, leading to inflammation and disruption of the gut barrier. Increased permeability of the gut lining (leaky gut) can release endotoxins into the bloodstream, triggering immune responses and inflammation.
Besides whole foods, fermented foods like yogurt, kefir, cheese, and sauerkraut might nourish the gut microbiota and increase the production of short-chain fatty acids, which have anti-inflammatory effects in the gut.
Electrolytes, like sodium, potassium, magnesium, and calcium, are essential for maintaining proper nerve and muscle function, including in the gut. When the body is dehydrated, electrolyte imbalances can disrupt gut motility and digestive function.
Dehydration can also lead to changes in mood and cognitive function, which can negatively impact the brain-gut axis. When the brain is dehydrated, cognitive function can be impaired, leading to changes in mood, behavior, and cognitive performance.
Drinking enough water with electrolytes is essential for proper gut and brain function. Dehydration can lead to constipation and other digestive issues that can negatively affect the gut and the brain. Staying hydrated can improve gut and brain health and the communication between the brain and the gut.
In addition, giving rest to the gut by refraining from food for a while can significantly improve the gut and brain health. For example, you might try intermittent fasting or fast-mimicking diets if you don’t have underlying health conditions.
3 — Manage stress systematically with fundamentals and supplementary activities.
Oxidative and chronic stress can negatively affect gut and brain health and the communication between the brain and the gut.
Managing stress through fundamentals like sleep and exercise and supplementary activities like fun, mindfulness, meditation, and cognitive behavioral therapy can lower the risks of dysregulating the brain-gut axis.
Exercise can increase blood flow, oxygenate cells, and release biochemicals that improve gut motility, microbiota diversity, and brain function.
The body repairs and regenerates tissues regulates hormones, and consolidates memories during restorative sleep. Disruptions in sleep patterns can alter gut microbiota and increase intestinal permeability (leaky gut) and chronic inflammation, leading to dysregulation of the brain-gut axis.
Cortisol is a stress hormone that can disrupt the gut microbiota when elevated and increase intestinal permeability, while melatonin has anti-inflammatory and antioxidant properties that can protect the gut lining. Restorative sleep can regulate these hormones, maintaining a healthy brain-gut axis.
Even though cortisol has been used for inflammation recently, it was found that it causes inflammation too. Cortisol creates a paradoxical situation. For example, A paper in Nature explains that
“The researchers were surprised to learn that glucocorticoids cause gut inflammation because these compounds are sometimes used to treat IBD. This apparent paradox might be explained by the short time frame in which such treatments are used. Although quick bursts of glucocorticoids seem to be anti-inflammatory when stress becomes chronic, “the system completely shifts,” and glucocorticoids take on a pro-inflammatory role.”
Managing stress through meditation, yoga, deep breathing, and various physical and mental therapies can reduce the adverse effects of stress and inflammation on the gut and the brain.
Psychology and psychiatry literature indicates that cognitive Behavioral therapy (CBT) has been shown to reduce symptoms of irritable bowel syndrome (IBS) and other gut-related disorders.
This review paper informs that “psychological therapies have demonstrated efficacy in reducing the severity of IBS symptoms. Cognitive-behavioral therapy has been tested rigorously in multiple randomized controlled trials and consistently demonstrates significant and durable effects on IBS symptoms and quality of life.”
These techniques can modulate the release of hormones and neurotransmitters, positively impacting gut and brain health. Mindfulness practices can also promote the release of anti-inflammatory cytokines.
Conclusions
The brain-gut axis is a communication system that connects the central nervous system with the enteric nervous system in the gut. It is a bidirectional communication.
Disruptions in the brain-gut axis can lead to various health problems, including gastrointestinal disorders, mood disorders, and neurological conditions.
In addition, such disruptions can cause cellular alterations of the entero-endocrine and immune systems, which lead to abdominal pain, bloating, and diarrhea or constipation.
As I discussed, it is possible to improve the health of the brain-gut axis and prevent its dysregulation via healthy lifestyle habits and professional support.
As this system is highly complex and our knowledge is still limited, it is critical to obtain timely professional support to lower risks and get timely treatment.
Managing this system is also vital for fat loss. For example, a friend (Anna) who fixed her leaky gut lost 50 pounds. In addition, a leaky gut might lead to a leaky brain. I introduced seven steps to address it.
I have written about both digestive and brain health before. I link a few of them here if you are interested in details.
Make the Digestive System Healthier with 7 Lifestyle Methods.
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