Gut Brain Axis And Mental Health


How Does Stress Affect The Gut

The gut-brain axis: Grow your gut, Expand your mind | Omar Koussa | TEDxUniversityofBalamand

Stress and the gut are intimately connected, and the gut microbiome is a major influence on adaptation to stress. Stress negatively affects the diversity and complexity of the microbiome. But in a cruel twist of fate, the very reactivity to stress is affected by the composition of the microbiome. The relationship between stress and the gut takes on special importance as stress susceptibility plays an outsize role in common psychiatric conditions such as anxiety, depression, and PTSD. And it is thought to influence the waxing and waning of symptoms in many other conditions, including bipolar disorder and schizophrenia.

At the simplest level, stress can promote consumption of highly palatable comfort foods, loaded with simple carbohydrates, and directly influence which gut bacteria thrive. In addition, stress can reshape the composition of the gut bacteria through the actions of the hormone cortisol, released by the brain’s hypothalamic-pituitary-adrenal axis in response to the perception of threat to prepare the body to meet a challenge or flee from it. An array of changes occurs quickly, including alteration in the diversity and function of the gut bacteria. Studies show, for example, that gut bacteria have the ability to sense cortisol in their environment and change their gene expression in response to it.

Itraq Labeling And Strong Cation Exchanger

The pooled samples were labeled using iTRAQ reagent according to the manufacturers instructions . We used six tag of each iTRAQ 8-plex reagent ranging from 113 to 118. Four iTRAQ-labeling reagents were used for the 24 pools from the four tissues. iTRAQ-labeled peptides were fractionated by SCX chromatography using the AKTA Purifier system . The mixed iTRAQ-labeled samples were dissolved in buffer A and were then eluted at a flow rate of 1ml/min with a gradient of 08% buffer B for first 22min, 852% buffer B from 23 to 47min, 52100% buffer B from 48 to 50min, 100% buffer B from 51 to 58min, and buffer B was reset to 0% after 58min. The elution was monitored by absorbance at 214nm, and fractions were collected every 1min. For each experiment, 33 fractions were collected.

Gut Microbes Make Other Chemicals That Affect The Brain

The trillions of microbes that live in your gut also make other chemicals that affect how your brain works (

16 ).

They make SCFA by digesting fiber. SCFA affect brain function in a number of ways, such as reducing appetite.

One study found that consuming propionate can reduce food intake and reduce the activity in the brain related to reward from high-energy food .

Another SCFA, butyrate, and the microbes that produce it are also important for forming the barrier between the brain and the blood, which is called the blood-brain barrier .

Gut microbes also metabolize bile acids and amino acids to produce other chemicals that affect the brain .

Bile acids are chemicals made by the liver that are normally involved in absorbing dietary fats. However, they may also affect the brain.

Two studies in mice found that stress and social disorders reduce the production of bile acids by gut bacteria and alter the genes involved in their production (

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Excitement In The Field Of Gut

This crosstalk in communication between the brain and digestive system is opening up new ways to think about diseases. Not only do the gut and the brain communicate through the nervous system, but also through hormones, and the immune system. Microorganisms in the gut help regulate the bodys immune response. Medical researchers who are studying depressive symptoms, Parkinsons and Alzheimers disease, autism, amyotrophic lateral sclerosis, multiple sclerosis, pain, anxiety and other neuro conditions are beginning to look at what is going on in a person’s guts. Researchers who are investigating ulcers, constipation and other GI conditions also now have a reason to focus on aspects of brain functioning.

What The Research Says

Mental Health and The Gut

has demonstrated that stress may impact the functioning of the gut, including:

  • changing the composition of the gut microbiota
  • impairing the function of the intestinal barrier
  • impairing the speed, strength, and coordination of the digestive muscles
  • dysfunction of the immune and neuroendocrine systems

The combination of these effects can worsen IBS symptoms and may contribute to the symptoms of pain and bowel movement dysfunction.

2020 research demonstrates that stress can affect the microbiota of the gut. The gut microbiota is the collection of microorganisms, such as bacteria, that exist in the bodys gastrointestinal tract. These microorganisms provide benefits to the body, such as integrity to the gut and protection against foreign material.

The 2020 study also demonstrated that stress could affect the composition of the gut microbiota through stress hormones and inflammation. This may increase the risk of developing conditions such as IBS and depression.

A recent 2022 study on mice indicated that the mice experienced IBS-like symptoms when subjected to psychological stress without any inflammation or changes to the gut.

Researchers still need to explore this in humans to provide conclusive evidence that the effects are consistent with animal studies.

connection between the central nervous system, which includes the brain, and the enteric nervous system, comprised of the nerve connections to the gut.

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Neurotransmitters And The Gut Microbiome

Neurotransmitters are chemical messengers involved in a variety of functions in your body. They are produced in both your brain and your gut and are another part of the gut-brain connection.

Your gut microbiome can influence the production of some neurotransmitters. These include serotonin and gamma-aminobutyric acid , which are both important for your emotional well-being.

Your gut produces a large proportion of your bodys serotonin, and studies have shown that your microbiome helps regulate this.

How To Improve Your Gut Microbiome

The main way to improve the health and functions of your health microbiome is through diet. A healthy diet can improve your gut microbiome and boost your mental health.

A diet rich in fruits and vegetables, nuts, and seeds, whole-grains, legumes, and mostly a whole plant-based diet will improve the population of healthy microbes in your gut.

These foods will also increase the diversity of the healthy microbes present in your gut. A special class of food to include in your daily diet to boost your gut health is probiotics.

Probiotics are rich in healthy microbes, and ingesting them will improve your gut microbiome and affect your mental health positively.

Probiotics are gotten by fermenting healthy foods such as fruits vegetables, grains, and even organic dairy. You can find probiotics in fermented foods like sauerkraut, kefir, and yogurt.

They are also available in the form of supplements. They are many strains or probiotics and each has its own unique functions on the body. Prebiotics are simply the foods eaten by the probiotics in your gut.

They help them multiply and carry out their functions. Prebiotics are found in high-fiber foods, whole grains, garlic, onions, legumes, fruits, vegetables, nuts, etc.

They act as fuel for the healthy microbes in your gut. This will help them grow and thrive. Increasing your intake of prebiotics will have a direct influence on the gut-brain axis, and this, in turn, would boost your health, mood, and even behavior.


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How Does The Gut

Your microbiomethe diverse population of microbes that live in your gastrointestinal tractplays an important role in the health of your gut, and in other aspects of your physical health, from inflammatory skin disorders to obesity.¹ Researchers now say that this role of promoting good health may extend to include the health of your brain and neurological systems.

The Best Diet For Mental Health

âMicrobiota-Gut-Brain Axis and Mental Healthâ?

For years, researchers have examined the relationship between the foods we eat and their effects on our health.

The traditional eating habits of those who live in Mediterranean countries have stood out in multiple studies as beneficial for mental health, cognitive function and overall health. Other popular diets for cognition you may have heard of such as the MIND diet, are also based on many of the principles of the Mediterranean diet.

So what exactly is the Mediterranean diet? Its a style of eating that emphasizes fresh fruits and vegetables, beans, legumes, whole unrefined grains, and healthy fats from nuts, wild fish, and olive oil. This type of diet has shown to be very helpful in controlling inflammation and balancing blood sugar. Numerous studies have found that a Mediterranean diet is linked to a reduced risk of both mental and physical health issues.

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Neurotransmitters Are Influenced By Gut Bacteria

The bacteria in your gut are also responsible for producing many of the neurotransmitters that play key roles in your brain, and overall mood and mental health. Serotonin, which is known as the “happy” chemical or hormone, is largely produced in the gut. Researchers estimate that about 90% of all of your serotonin is made in the gut. One of the ways this happens is via bacteria that send signals to the gut to make serotonin.

Other neurotransmitters that play a role in mood and mental health are dopamine, GABA and norepinephrine, all of which are also produced in the gut. There is still a need for more research on these connections to fully understand how they work.

What Else Can We Eat To Improve Our Mental Wellbeing

Foods containing tryptophan Serotonin isnt available in the diet, but there are many dietary sources of its precursor, tryptophan. Highest amounts are found in certain seeds and nuts . Soybeans are also a good source of tryptophan, followed by cheeses, red meat, poultry, fish, sea foods, oats, beans and lastly, eggs.

PrebioticsPrebiotics are non-digestible oligosaccharides that promote the growth of gut bacteria. They occur naturally in vegetables, such as chicory, onions and Jerusalem artichokes and are commercially available in a range of nutraceutical products, supplements and functional foods.

Some of these oligosaccharides can also affect mood. For example, administration of a particular prebiotic containing galactooligosaccharides to healthy human participants improved the processing of emotional information and hormonal responses related to anxiety.

GABAGABA is a neurotransmitter that plays a key role in the functioning of the central nervous system and is involved in the aetiology of depression. It can be produced from glutamic acid and its salt, glutamate, by some probiotic bacteria in the GI tract.

Many foods contain glutamic acid, including fish, eggs, dairy products, meat and particularly soy protein. Functional foods, such as confectionery, beverages and supplements, containing high levels of added GABA are also widely available. Probiotic supplements and foods may also increase GABA levels in the gut.

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The Gut Microbiome May Alter Cognition Through The Immune System

The gut microbiome also speaks to and may influence the brain by way of the immune system. Alterations in immunity are linked to an increased risk for developing diminished cognitive function, including risk for Alzheimers dementia. Very high spikes in inflammation are linked to delirium, a state of confusion, and generally altered mental status. Since the gut microbiome directly communicates with and influences immune cells , the link between immunity, cognition, and the gut microbiome is certainly worth knowing.

What Role Does The Vagus Nerve Play

Mental Health and The Gut

Vagus means wandering, and the vagus nerve, the longest in the bodyreaching from the brainstem to the abdomen, with branches to all the visceral organsis a prominent component of the gut-brain axis. The vagus nerve oversees many body functionsheartbeat, for onebut as the main highway connecting brain and gastrointestinal tract, it sends information about the state of the gut to the brain, delivering it to important information about, say, hunger, or the need for specific nutrients.

In the course of digesting food, the bacteria of the microbiome produce many substances that act on the nervous system. Chief among them are neurotransmittersincluding serotonin and GABAknown to be involved in many psychiatric disorders. There are many other neurally active substances produced in the gut as well, and they send signals to the brain via the vagus nerve or are directly transported to the brain by the vagus nerve. In addition, the vagus nerve brings to the brain news of the bodys inner sensations, an awareness known as interoception. Because it is a two-way road, the vagus nerve is also a pathway by which thoughts and feelings affect the operation of the intestinal tract.

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Ways To Improve Mood/mental Health

Before all else, you should seek the guidance of a mental health professional. Unnecessary stigmas surrounding mental health has slowly become lifted. There is nothing to be ashamed of. According to the World Health Organization , 450 million people suffer from mental illness *. So, please reach out for help.

What Is Leaky Gut

The intestinal walls serve as an important barrier, separating the contents within from the rest of the body. The intestines have specific mechanisms for transporting contents, such as nutrients, from within to the other organs for everyday functioning and for growth and repair. As understanding of the gut microbiome increases, it is becoming clear that under some conditions, the intestinal walls lose their integrity they become permeable, creating a condition known as leaky gut.

Under these circumstances, whole microbes, their byproducts, other bacterial materials, and poorly digested proteins and fats can inappropriately find their way out of the gut and into to the general circulation and distant tissues, creating inflammation and injury. Bacteria that are normally not pathogenic within the environment of the gut set off pathologic processes in other organ systems. While the processes are not yet fully understood, leaky gut is increasingly associated with a number of conditions, including metabolic and psychologic disorders. Chronic inflammation stemming from leaky gut processes may set off depression, for example, and it may also explain the link between heart disease and depression. It is also thought to play a role in autism.

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Probiotics Prebiotics And The Gut

Gut bacteria affect brain health, so changing your gut bacteria may improve your brain health.

Probiotics are live bacteria that impart health benefits if eaten. However, not all probiotics are the same.

Probiotics that affect the brain are often referred to as psychobiotics (

26 ).

One small study of people with irritable bowel syndrome and mild-to-moderate anxiety or depression found that taking a probiotic called Bifidobacterium longum NCC3001 for six weeks significantly improved symptoms .

Prebiotics, which are typically fibers that are fermented by your gut bacteria, may also affect brain health.

One study found that taking a prebiotic called galactooligosaccharides for three weeks significantly reduced the amount of stress hormone in the body, called cortisol .


Probiotics that affect the brain are also called psychobiotics. Both probiotics and prebiotics have been shown to reduce levels of anxiety, stress and depression.

How Important Is A Balanced Microbiome

“Brain-Gut Axis: The Effect of Intestinal Microbiome on Mental Health” – Dr Emily Deans

The lack of a diverse array of bacteria in the gut has a namedysbiosis. The condition is negatively associated with body weight, body mass index, triglyceride and LDL cholesterol levels, insulin-resistance, and blood pressure.

Dysbiosis is increasingly viewed as a marker for many health disorders. Dysbiosis of the gut microbiome causes dysfunction in the intestine leading to inflammatory, immune, metabolic, and infectious diseases in the intestines but its effects extend was beyond through metabolic, inflammatory and hormonal pathways as well as the gut-brain axis.

Researchers have detected shifts in the balance of gut bacteria in a number of psychiatric disorders, suggesting that gut bacteria help mold the brain. For example, those with major depression seem to have a decrease in the number of Firmicutes and an increase in Bacteroidetes. Patients with autism spectrum disorder, compared to control subjects, have been shown to have increased levels of Clostridia, Desulfovibrio, Sutterella, andBacteroides species, and decreased levels of Firmicutes, Prevotella, andBifidobacteria, but researchers are not sure whether the microbial changes in autism spectrum disorder are causes or effects of the condition.

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The Gut Microbiome And The Immune System

The immune system is your bodys protection against disease. Its a network of cells, chemicals, and organs that work together to fight harmful bacteria, fungi, and viruses.

It is also a crucial component of the gut-brain connection. Just as your immune system can impact your gut health, your gut microbiome can directly affect your immune system.

A large proportion of your immune system is actually found in your gut.

Research has shown that gut bacteria can have an effect on immune cells in both your gut and brain, indicating the gut microbiomes importance for immune health.

Although theres still a lot to learn about how gut microbes affect the immune system and brain function, scientists know that the bacteria in your gut can influence the level of proteins called cytokines.

These proteins are essential to your bodys inflammatory response and can affect brain function.

Is Your Diet Fueling Depression

The Gut-Brain Axis is influenced by several factors, but none more so than diet. Poor diet has been linked to cases of chronic depression and anxiety. Most frequently, depression is associated with gastrointestinal inflammation caused by poor diet. While its still not 100 percent certain how much poor gut health causes depression, theres little doubt that the two are inextricably linked.

More often than not, sugar and processed foods are associated with poor gut health and depression. In severe cases, too much of these foods can lead to swings in blood sugar , which can lead to mood changes. High levels of sugar also lead to increased inflammation of the digestive system, negatively affecting the Gut-Brain Axis. Other culprits include hard to digest molecules like gluten, and bad fats found in certain cooking oils. These oils inhibit healthy cellular triggering in the brain, and tend to aggravate any symptoms of depression.

The best thing to do to eliminate foods that could cause depression is to stay away from processed foods. Instead, switch to ingesting probiotics and naturally fermented foods to improve the balance of friendly bacteria in the digestive system. Its also wise to get tested for any hidden food intolerance, as this can also result in increased inflammation and risk of depression.

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