The biggest Gut health and gut-brain axis in the human body Natural fat burner for lean muscles the times of the agricultural society Gu the industrial society may Gut health and gut-brain axis be healtg the Non-pharmaceutical emotional support genes, zxis in the commensal microbiota with which we coexist Gomez, ; Axks et al. Do the gut changes have anything to do with the mental states? Food Chem. In contrast, antibiotic treatment after the onset of the first signs of spontaneous EAE did not affect the ongoing disease and CNS inflammation Over the past few decades, researchers have discovered that the brain and the gut communicate in many more ways than once thought and they talk about many things, from hunger to happiness to how much power your brain cells need to generate your thoughts.

Gut health and gut-brain axis -

In addition, the gut-brain axis engages in constant crosstalk with other major systems of the body, including the immune system and the neuroendocrine system, which plays a prominent role in the stress response.

As a result, the microbiome is increasingly linked to immune function and immune disorders and a range of metabolic disorders as well as to mental health and psychiatric conditions.

The world is full of microbes, and there are far more of them than of us. The microbiome refers the trillions of microorganisms, including bacteria, that normally live in and on humans and which perform important functions for us.

There are bacteria and other microorganisms living on the skin and on mucous membranes, but microbes are most concentrated—said to number about trillion and weigh about a kilogram—in the gut, primarily in the large intestines, or colon.

There they help us digest the complex sugars in milk and break down dietary fiber to get some important substances out of them. Over the past several years, researchers have discovered that they are key regulators of overall health. Among many other functions, they play a major role in metabolism and in immune function throughout the body, and they directly and indirectly affect nervous system function, including susceptibility to stress and responsiveness to negative stimuli.

The gut microbiome, the name for the trillions of biologically active microorganisms living in the intestines, is emerging as a key modulator of the human nervous system and other systems of the body. Gut bacteria produce substances that are neurally active.

For example, The action of gut bacteria on fiber-rich foods results in the production of short-chain fatty acids, important as regulators of the integrity of the intestinal wall, as signaling molecules in the nervous system, and as regulators of stress reactivity.

Gut microbes also produce or cause to be produced neurotransmitters including serotonin, affecting brain functions such as sleep, mood, and cognition.

Studies—most conducted on animals—show that gut bacteria influence development of the brain, particularly in early life and at adolescence ; they stimulate the growth of new neurons in the brain and new neural connections throughout life.

They play a role in memory, social behavior, stress reactivity, and more. The microbes that live in the gut represent thousands of different species of bacteria, and that is a good thing. Diversity of the gut microbiome is strongly linked to both mental and physical health. The diversity of the gut microbiome is heavily dependent on what you eat.

There are thought to be somewhere between 1, and 1, distinct species of bacteria residing in the gut. The composition of the microbiome varies somewhat from person to person but in each individual is relatively stable. Nevertheless, it changes in response to what we do, where we are, and, especially, what we eat.

The most abundant bacteria in a healthy gut belong to a phylum called Firmicutes; they have been shown make up about 80 percent of a well-balanced microbiome. Another prominent phylum of bugs in the microbiome is Bacteroidetes, constituting about 15 percent of a balanced microbiome.

They are known for the many metabolic tasks they perform on our behalf, such as breaking down complex carbohydrates, or polysaccharides, from fiber-rich plants. In contrast to Bacteroidetes, Firmicutes have a negative influence on glucose and fat metabolism.

The relative proportion of Bacteroidetes to Firmicutes is thought to drive gut bacterial diversity. An increase in the ratio of Firmicutes to Bacteroidetes has been linked to weight gain, gut inflammation, and an increase in pro-inflammatory cells circulating in the body.

The lack of a diverse array of bacteria in the gut has a name—dysbiosis. The condition is negatively associated with body weight, body mass index, triglyceride and LDL bad 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 , and Bacteroides species , and decreased levels of Firmicutes, Prevotella, and Bifidobacteria, but researchers are not sure whether the microbial changes in autism spectrum disorder are causes or effects of the condition.

There is not one single microbiome profile that is healthy. Many species of gut bacteria have overlapping functions allowing different bacteria to take on the same role in different people.

Two unrelated people typically share only 40 percent of their microbial species , researchers find. Because the microbiome is sensitive to where we are, what we do, and what we eat, engaging in physical activity can alter the composition of the microbiome, in positive ways.

Stress disturbs the balance of bacteria in the gut. Taking medications, especially antibiotics, and especially during childhood , kills off many beneficial bacteria in the gut. But everyone who eats a high-sugar, high-fat diet will shift the composition of the gut microbiome by increasing the proportion of several classes of bacteria relative to others that produce health-enhancing substances.

Most bugs in our gut come from the environment we live in. In fact, infant guts are first colonized by bacteria on the way down the birth canal. In addition to conventional nutrients, breastfeeding supplies many important substances stimulating the development of a healthy gut microbiome.

The foods we eat are major representatives of the environment we live in. At every stage of life, the composition of the gut biome and the diversity of bacteria in it are heavily dependent on diet. Studies show, for example, that it takes less than two weeks for a switch from a good plant-rich diet to an American-type diet— characterized most notably by high-fat red meats and industrially processed foods—to induce changes in microbiome.

Some animal studies find changes beginning in as little as a day. Almost every component of diet, including common nonnutritive additives used in commercial food production, has been shown to have an effect on the microbiome. Even if the additives supply no calories or nutrients, they can destroy bacteria in the gut—one more reason the typical American diet, loaded with highly processed and additive-heavy foods, is bad for the microbiome.

Among them are artificial sweeteners, thickeners, emulsifiers, food colorants, and preservatives. The gut talks to the brain constantly and rapidly. There are direct connections between the gut and the brain, the major one being the vagus nerve.

The gut also produces neurotransmitters that relay messages to the brain. There are many indirect ties, such as short-chain fatty acids, substances produced by bacterial action in the gut that act on nerve pathways or circulate to the brain or stimulate processes that affect the brain.

These activities are currently under intensive research, because they suggest new ways of approaching treatment of both psychiatric conditions and gastrointestinal problems. Vagus means wandering, and the vagus nerve , the longest in the body—reaching from the brainstem to the abdomen, with branches to all the visceral organs—is a prominent component of the gut-brain axis.

The vagus nerve oversees many body functions—heartbeat, for one—but 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 neurotransmitters—including serotonin and GABA—known 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.

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. The therapeutic implications of this understanding are huge. The vagus nerve can be used as a channel for improving disordered brain function; manipulation of the microbiome by diet is one significant way.

It is also possible to directly target the vagus nerve as treatment for both psychiatric disorders and such somatic conditions as irritable bowel syndrome and inflammatory bowel disease.

Short-chain fatty acids SCFAs are an important class of biologically active substances produced in the gut, specifically by the action of gut bacteria on plant-derived foods containing fiber that is otherwise resistant to digestion, such as artichokes and legumes. SCFAs are emerging as important contributor to metabolism, immunity, and mental health.

But exactly what those roles are is very much a developing story. Fibrous foods pass through the stomach and small intestine intact but meet a special group of bacteria in the lower intestines, or colon, that work them over by fermenting them— releasing energy, gases, and SCFAs, the most common of which are acetate, propionate, and butyrate.

Acetate, produced by Bifidobacteria, Lactobacilli, Akkermansia, and species of Prevotella and Ruminococcus, regulates the acidity of the gut, which keeps pathogenic bacteria under control.

It also boosts gut diversity by nourishing other bacteria in the gut, and, through actions on cells lining the gut, helps regulate appetite. Butyrate, produced by members of the Firmicutes family such as Faecalbacteria and Roseburia , is a local source of energy powering cells lining the colon.

But it does much more. Butyrate is especially important for mental health. It is active as a neurosignaling agent in the gut-brain axis, and it activates the vagus nerve. Studies show that butyrate crosses the blood-brain barrier and stimulates neuroplasticity in the brain.

Animals studies show it raises levels of BDNF, brain-derived neurotrophic factor, crucial to learning and memory. By its chemical nature, butyrate is an anti-inflammatory molecule, extinguishing inflammatory processes wherever they occur, including the brain.

Propionate, produced both by Bacteroidetes and Firmicutes, is also ani-inflammatory, and it helps regulates appetite. SCFAs are one of the many ways the gut communicates with the brain.

They serve as signaling molecules throughout the body—mobilizing hormones and activating nerve pathways and many types of cells to regulate appetite, energy balance, body weight, immunity, brain function, and mood states.

Butyrate also helps protect the brain, shielding it from toxins and infectious agents by maintaining the integrity of the blood-brain barrier. In addition, SCFAs are essential to liver function, regulate the activity of immune cells, and stimulate the sympathetic nervous system.

Studies show that depressed people have far less diversity of the microbiome than do people who are not depressed. One distinguishing feature of the Mediterranean diet is the predominance of such foods, and the production of SCFAs is believed to account for many of the mental and physical health benefits of the Mediterranean diet.

It is closer than the highly processed American diet to what our ancestors ate for most of human history—a hardscrabble diet in which nuggets of nutrients came bundled in indigestible plant material.

The human gut was adapted to a diet of more than grams per day of fiber from foraged food—compared with the fewer than 15 grams of fiber a day supplied by the typical Western diet of highly processed, energy-dense foods.

Recent research has demonstrated that neurotransmitters are not confined to regulating activities within the brain; they play a large role, for example, in the gut. Both bacteria in the gut and the cells lining the intestines produce neurotransmitters, among them GABA, serotonin, dopamine , and acetylcholine.

Exactly how the neurotransmitters produced in the gut influence the brain is not clear, but it is the object of intense research. There is a nerve mesh that surrounds the intestines—it is called the enteric nervous system—and it communicates both with gut bacteria and, through the vagus nerve, the brain.

It is thought that the neurotransmitters produced by the gut act on the brain via the enteric nervous system. When the microbiome read: the poop of depressed people is transplanted into the intestines of germ-free animals, those animals display many of the behaviors of depression—they lose interest in pleasurable activities, they stop exploring and socializing, and they display signs of anxiety.

The researchers transferred the blues. In other studies, researchers removed fecal matter from human subjects suffering from schizophrenia and transplanted it into mice.

The mice developed many schizophrenia-like behavioral abnormalities. There is evidence that, in both cases, a lack of diversity of gut bacteria disrupted the conversion of tryptophan, a component of food, into serotonin. 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.

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. The composition of the gut microbiome is believed to directly affect the permeability of the intestinal barrier.

Various diet components are also known to have effects on intestinal permeability. For example, proteins such as casein and other nutrients such as vitamin D and the mineral zinc have a beneficial effect on intestinal permeability, while alcohol increases gut permeability.

Meat proteins, in the course of digestion, release substances that impair the intestinal barrier integrity.

By contrast, short-chain fatty acids, produced by microbes acting on resistant carbohydrates in the colon, play an important role in maintaining the integrity of the intestinal barrier.

Because the gut-brain axis is a two-way channel, it provides a pathway for the gut and its operations to influence the brain and its activities and for brain states to influence the gut. Just as disturbances of the gut microbiome can undermine mental health, and disturbances in thinking can throw gut operations into disarray, so can the influence be positive.

Growing understanding of the gut-brain axis not only puts a new emphasis on the role of diet and the composition of the microbiome in health and disease but is expected to provide new ways of intervening in disorders of both mental function and gut function.

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. Researchers have found that specific strains of gut bacteria influence fear learning and extinction, processes at the heart of anxiety conditions such as PTSD.

In studies of one strain of beneficial gut bug, Bifidobacterium longum , fed to healthy men for a month, the subjects displayed reduced levels of stress measured psychologically and physiologically after being subjected to a challenge; researchers recorded a blunted hormonal response to stress.

Studies suggest that there are specific times during development when the threshold of stress responsiveness is set by the composition of the gut microbiome—just before and after birth, and again at adolescence, all periods when there is rapid growth of connectivity between brain cells.

Preclinical studies indicate that shifts in the normal composition of the microbiome early in life—through Caesarean birth, lack of breastfeeding, antibiotic exposure, infection, or significant stress exposure—can enduringly influence stress physiology and influence the risk for depression and many other psychiatric disorders.

An increase in levels of cortisol, the physiologic hallmark of stress, increases the permeability of the gut. That, in turn, allows the leakage of bacterial substances that set off inflammatory processes throughout the body, including the brain, activating yet another pathway of disorder.

Evidence that the makeup of the microbiome plays a major role in depression took a giant leap forward when, in , researchers transplanted into healthy, germ-free rats the poop of people suffering from depression.

The animals lost interest in pleasurable activities, they stopped exploring and socializing, and they displayed signs of anxiety—the classic behavioral abnormalities seen in depression. There are many ways the composition of the gut microbiome and the activity of the gut-brain axis can lead to depression.

Multiple studies have established that the microbiome of depressed people lacks bacterial diversity.

The lack of diversity of gut bacteria can lay the groundwork for depression by rendering people overreactive to stress. A lack of bacterial diversity can diminish the conversion of tryptophan, a component of food, into the neurotransmitter serotonin.

Veterinary Clinics of North America: Small Animal Practice, 48 3 , — Salman, M. Behavioral reasons for relinquishment of shelter dogs and cats to 12 shelters. Journal of Applied Animal Welfare Science, 3 2 , 93— Tanaka, A. Associations among weight loss, stress, and upper respiratory tract infection in shelter cats.

Journal of the American Veterinary Medical Association, 5 , — Landsberg, G. Great Britain: Saunders Elsevier. Mills, D. Stress — Its effects on health and behavior: A guide for practitioners. Veterinary Clinics of North America: Small Animal Practice, 44, — Mariti, C.

Journal of Veterinary Behavior, 7 4 , — Seibert, L. Diagnosis and management of patients presenting with behavior problems.

Veterinary Clinics of North America: Small Animal Practice , 38 , — Patronek, G. Attitudes, procedures, and delivery of behavior services by veterinarians in small animal practice. Journal of the American Veterinary Medical Association , 11 , — Home Science of Nutrition Promoting Gastrointestinal Health The Gut-brain Axis.

The Gut-brain Axis. This system communicates subtle changes within the gastrointestinal tract to the brain via the vagus nerve.

Primary pathways through the vagus nerve mediate communications between the gut microbes and the CNS. The sympathetic nervous system: The release of adrenaline and noradrenaline from the brain and adrenal glands leads to the behavioral responses of fight, flight, or freeze, and can also alter gut motility.

Which species of bacteria were living in these tiny newborn guts, already teeming with microbial life? But the scientists were not studying bacteria, exactly. According to a developing theory about the role these bacteria play in cognition, their poo offered an exciting new perspective on their minds.

Thus did these babies, now about four years old, become a special cohort of a few dozen boys and girls at the leading edge of what may be the hottest new area in science, the Gut-Brain Axis. The experiment their parents signed up for was a pilot study for this idea that is revolutionizing neurobiology, even challenging old ideas about what consciousness is and where it comes from.

These babies were early guinea pigs in the investigation of how closely the human mind, with all its wondrous powers of thought and feeling and unconscious control of bodily functions, depends on the human gut, with all its millions of resident bacteria. But each brought a potential contribution.

If they found a strong correlation with any particular microbe, or combination of them, it might point somewhere interesting. It might help explain why the brain, a bundle of neurons in the skull, seems to be so deeply affected by bacterial activity in the gut, a machine for digestion far away down in the belly.

So, they imagined an experiment. It would be nothing definitive, more like a survey of normal healthy infants, looking at the development of their brains alongside the bacterial contents of their bowels.

They wanted to see just how closely the gut is linked to the brain, not just through nerves, but through the behaviour and chemical byproducts of bacteria. Known as the Gut-Brain Axis, this concept arose out of insights that some conditions with psychological aspects, such as autism or depression, are correlated with digestive disorders, such as irritable bowel syndrome.

It remains a field of vast promise but sparse certainty. Finlay, who runs a lab at the University of British Columbia that studies the interactions of microbes and their hosts, in health and disease, calls it the hottest area in science. Never mind malnutrition or asthma or immunology or the many other human medical issues that are related to bacteria in the gut.

The Gut-Brain Axis is the next frontier in studies of the human microbiome, and all his young researchers are clamouring to pursue it, Finlay says.

The future of brain science is the belly, and vice versa. Thanks to genetic sequencing technology that allows for easy cataloguing of bacteria, this field is starting to give up its secrets, and raising plenty of tantalizing new questions. If bacteria are involved in the emergence of mental disorders, perhaps they are the key to cures.

If bacteria are crucial to normal brain function itself, maybe they can be harnessed, guided, controlled, influenced.

Maybe treating the brain means treating the gut, both in the everyday and the medical sense. Maybe disease can be averted, and health improved. There are early clues all of this is the case. It is a nascent theory in search of evidence to refine it into practical knowledge.

Finlay said he was struck with a sense of anxious fear about what he might find. He was worried they were about to find a bacterium that would be correlated with better cognitive development.

Parents would demand it, raising all kinds of ethical questions. Dread filled his mind at the prospect of any strong positive results. People already get pretty excited about bacteria when they hear fermented foods such as yogurt and kimchee, or probiotic supplements can make their tummies feel better as their digestion goes more smoothly.

Wait until they hear which ones make you think better, too. Research on the Gut-Brain Axis hints at a whole new view of brain health and disease, Finlay said, even a whole new view of neurobiology itself. The current trouble is that the field is young, and the depth of these connections is only really starting to show itself.

They found a couple of correlations between gut microbiota and infant cognitive ability that hint at future discoveries and will inspire future research. Finlay tried to be cautious as he explained them. He spoke of clues and hints, pushes in this direction or that.

But he acknowledged the research had validated the interest and effort. Bacteria have traditionally had a negative reputation as regards human health.

They are the cause of untold trouble, from plague and sepsis to food poisoning and all kinds of nasty infections. It was not until relatively recently in scientific history that their benefits started to show themselves.

Now, it is well established that digestion depends on gut bacteria. A whole field of consumer marketing is devoted to packaging bacteria as the key to healthy tummies, delivered through food products that boast about their bacterial content, from fermented sauerkraut to yogurt and even soda water.

Industry is cashing in. The U. There are probiotic drops for babies, all sorts of pills for women, and Garden of Life Probiotics Prostate capsules for the fellas, guaranteeing 15 strains and 50 billion individual microbes. There are kosher probiotic ground chia seeds, and halal probiotic yogurt.

And, of course, there is probiotic dog and cat food. All of these marketing pitches are premised on the idea that ingesting good bacteria keeps things orderly in the intestines. But cognition?

Emotional feeling? Consciousness itself? We know bacteria help us digest. We could not do it without them. It would be astounding if the same were true of thinking. But the idea has a lot going for it, in new and exciting experimental results, long-established medical science and even in ancient intuitions about human nature.

In a sense, gut already means brain. To trust your gut means to trust the instincts that nature has endowed in your mind, silently guiding behaviour based on evolutionary lessons. A gut feeling is inexplicable but powerful.

There is a snd communication system between the gut and brain gut-brsin the Memory improvement exercises for adults connection, or axis. It involves a complex Gut health and gut-brain axis of nerves and biochemicals. Experts now recognize anv gut-brain connection, axid has reshaped their understanding Gut health and gut-brain axis neurological and digestive health. This bidirectional communication system establishes that the gut is not just an organ for digestion — instead, it is pivotal in influencing mental health. For example, some individuals might feel a knot in their stomach when nervous or may face digestive upset during times of stress. Some research suggests that the brain can affect gut health, and the gut may affect brain health. The gut-brain axis is the bidirectional communication system between the digestive tract and the brain.