Our Second Brain.
The connection between our gut and our brain !
Have you ever had a “gut-wrenching” experience? Do certain situations make you “feel nauseous”? Have you ever felt “butterflies” in your stomach? We use these expressions for a reason. The gastrointestinal tract is sensitive to emotion. Anger, anxiety, sadness, elation — all of these feelings (and others) can trigger symptoms in the gut.
What is your gut?
The gut is a highly innervated organ that possesses its own nervous system known as the enteric nervous system (ENS) that is in constant communication with the central nervous system (CNS) through nerves such as the vagus, which directly connect portions of the gut to the brain.
The ENS is sometimes called the “second brain,” and it actually arises from the same tissues as our central nervous system (CNS) during fetal development. Therefore, it has many structural and chemical parallels to the brain.
The brain and the gut.
The brain has a direct effect on the stomach. For example, the very thought of eating can release the stomach’s juices before food gets there. This connection goes both ways. A troubled intestine can send signals to the brain, just as a troubled brain can send signals to the gut. Therefore, a person’s stomach or intestinal distress can be the cause or the product of anxiety, stress, or depression. That’s because the brain and the gastrointestinal (GI) system are intimately connected.
Given how closely the gut and brain interact, it becomes easier to understand why you might feel nauseated before giving a presentation, or feel intestinal pain during times of stress. That doesn’t mean, however, that functional gastrointestinal conditions are imagined or “all in your head.” Psychology combines with physical factors to cause pain and other bowel symptoms. Psychosocial factors influence the actual physiology of the gut, as well as symptoms. In other words, stress (or depression or other psychological factors) can affect movement and contractions of the GI tract, make inflammation worse, or perhaps make you more susceptible to infection.
Research has shown that the body is actually composed of more bacteria than cells. We are more bug than human! Collectively, these trillions of bacteria are called the microbiome. Most of those bacteria reside in our gut, sometimes referred to as the gut microbiota, and they play multiple roles in our overall health.
The gut is no longer seen as an entity with the sole purpose of helping with all aspects of digestion. It’s also being considered as a key player in regulating inflammation and immunity.
This collection of bacteria is influenced by several factors:
- What we eat
- How much stress we have
- How many antibiotics we take
- Whether we were born by cesarean section or through the vaginal canal
- Whether or not we were breastfed
- How many pesticides are on our food
- How “sterile” our environment is
A healthy gut consists of different iterations of bacteria for different people, and this diversity maintains wellness. A shift away from “normal” gut microbiota diversity is called dysbiosis, and dysbiosis may contribute to disease. In light of this, the microbiome has become the focus of much research attention as a new way of understanding autoimmune, gastrointestinal, and even brain disorders.
The ability of bacteria to synthesize and recognize the very same neurotransmitters that are found in the vertebrate host suggests a bidirectional environment where the microbiome can influence the host and the host influence the microbiome. This level of communication between host and microbiome and its mediation by a commonly shared evolutionary pathway of intercellular signaling suggest that “they monitor us” and “we monitor them”
Approaching the microbiome from a microbial endocrinology-based vantage point may provide an understanding of the specific pathways by which microorganisms may influence behavior and thereby lead to new approaches to the treatment of specific mental illness based on modulation of the microbiome-gut-brain axis.
“We may be able to reverse these ailments. If you turn off the faucet that produces this compound, then the symptoms disappear.”- Mazmanian, who in 2012 was awarded a MacArthur grant for his microbiome work.
Looks like in most cases of depression, anxiety, stress, autism the attention is given directly just to the brain, where as if we shift the attention to our gut and focus on what we are eating the whole problem can be reversed!
Effect on autistic kids
Approximately one in 88 children in the U.S. has an autistic spectrum disorder. Up to 70 percent of them have gastrointestinal (GI) abnormalities at some point during childhood or adolescence. They are 3.5 times more likely to have constipation or chronic diarrhea than children who are not autistic
What’s worse, the side effects of the psychotropic drugs that are prescribed to many autistic children may be intensifying the digestive issues. Once the GI issues are treated, aggressive and problematic behaviors sometimes subside.
“A lot of these kids, before they see me, have been trialed on many different psychotropic drugs to try to relax them, to calm them down,” Margolis, a pediatric gastroenterologist at New York Presbyterian Hospital and a researcher at Columbia University Medical Center.
“Many doctors don’t recognize that aggressive behavior is not part of autism,” Margolis said. “This is really a new field.” Research is showing that a common cause of autistic children acting out is simply because they’re constipated — which, from there, can mean they stop sleeping and eating well. They may become aggressive and frustrated because they have no other way of saying that their stomachs hurt.
Serotonin
Serotonin is best known for its role in the central nervous system. It regulates mood, appetite, and sleep — yet more than 90 percent of the body’s serotonin is actually in the gut. Dr. Michael Gershon, author of the The Second Brain: Your gut has a mind of its own and head of the gastroenterology lab at Columbia, was one of the first to study the role of serotonin in the gut — or, as he calls it, the enteric nerve system. His research shows that serotonin regulates movement within the intestines, which is critical to healthy digestion.
Probiotic (live bacteria) treatments in mice have been shown to reduce cortisol, an important stress hormone, and decrease anxious and depressive behaviours.
Diet
On the plus side, large studies show us that people who eat a balanced diet with all the usual good stuff (fibre, fresh fruit and vegetables) have lower rates of mental illness as adults and adolescents.
Clearly, diet affects both the gut microbiota and mental health. Research is ongoing to see whether it is a healthy gut microbiota that underlies this relationship.
You are what your “bugs” eat
What we choose to put into our mouths has such a profound impact on our health because each time we eat we either feed the good guys or the bad guys. When we consistently choose whole foods that are contain fiber, protein and beneficial fat sources, we are building a microbiome that will promote positive mood and an anti-inflammatory state of health. When we consistently make poor food choices, eating a diet high in refined carbohydrates and sugars and low in fiber,
we are setting ourselves up for inflammation in both mind and body. This aspect of nutrition is particularly important in the early stages of life, when the microbiome is first being established. If we think of the foods that American children usually eat (high sugar, high carb, no vegetables, etc…) we can start to see the influences on asthma, allergies, ADD, hyperactivity, poor immune function leading to recurring colds and obesity leading to Type 2 Diabetes and other metabolic diseases.
How our gut affects our sleep
Our mental health is closely linked to the quality and timing of our sleep. Now evidence suggests that the gut microbiota can influence sleep quality and sleep-wake cycles (our circadian rhythm).
A study this year examined patients with CFS. The researchers found that higher levels of the “bad” clostridium bacteria were associated with an increased likelihood of sleep problems and fatigue, but this was specific to females only. This suggests that an unbalanced gut may precipitate or perpetuate sleep problems.
There is emerging evidence that circadian rhythms regulate the gut immune response. The effect of immune cells on the biological clock could provide insights into the possible bidirectional relationship between sleep and the gut. For example, data from animal studies suggests that circadian misalignment can lead to an unbalanced gut microbiota. But this effect can be moderated by diet.
There is growing concern that disruptions to our circadian timing of sleep leads to a range of health issues, such as obesity, metabolic and inflammatory disease, and mood disorders. This is particularly important for shiftworkers and others who experience changes to their sleep/wake patterns.
How does stress affect the gut? And how does an imbalanced gut cause stress in the brain?
Interestingly, when we experience emotional stress in life, this stress is physically represented by the types of neurotransmitters and hormones that we produce. Adrenaline and cortisol are the biochemical representatives of stress in the tissues of the human body and both have profound effects on the health and integrity of the GI tract. The function of these chemicals is to put the body into “crisis” mode in response to a stressor. When the body is in crisis mode, it diverts blood flow away from the GI tract in order to supply the arms and legs with blood for running away from a dangerous situation. Repeatedly diverting blood from the GI tract causes the gut wall to break down, resulting in the “leaky gut” phenomenon. Stress chemicals also suppress the immune system so that it cannot weed out the “unfriendly” or “pathogenic” bacteria. Long-term stress causes break down of the physical tissues of the GI tract and leads to an imbalanced microbiome. From here, we see digestive disorders, poor absorption of nutrients, food allergies and systemic inflammation start to develop.
Once the integrity of the gut wall breaks down and we develop a poorly-balanced microbiome, the effects on the conscious “brain” and mental health are multi-fold. As 95% of the serotonin in the human body is produced in the GI tract, a “happy” gut is one that produces plenty of serotonin to share with the brain. “Friendly” bacteria themselves produce B Vitamins, amino acids, short-chain fatty acids and other molecules that human beings need to produce adequate serotonin and dopamine, our “happy” neurotransmitters.
This scenario completely changes when the GI tract tissue is damaged by stress and the microbial population favors “unfriendly” types of bacteria. In this unhappy situation, the gut is less likely to produce enough serotonin and the “unfriendly” bacteria produce chemicals that are over-stimulating to the brain, contributing to the pathology of anxiety and depression.
It is much easier and less risky to interrupt a dysfunctional gut-brain connection at the level of the gut than the level of the brain. Psychiatric medicine can, at best, take a guess at what’s going on in a depressed person’s Central Nervous System and prescribe a drug that may or may not be of benefit. This type of medicine is useful when a mood disorder renders a person non-functional, when the person is a danger to themselves or others, or when the person is not cognitively capable of caring for himself or herself appropriately. Cognitive Behavioral Therapy, a talk therapy technique that “reframes” the thought patterns of the person with depression to create a “sunnier” reality, is quite useful. This type of talk therapy benefits the biochemical side of depression by functionally reducing the amounts of cortisol and adrenaline a person produces in response to day-to-day situations. Reduction of these gut-damaging chemicals is quite beneficial for our gut-brain connection.
Here are some example of tests being done to prove the same,
-A recent study found that the addition of a “good” strain of the bacteria lactobacillus (which is also found in yoghurt) to the gut of normal mice reduced their anxiety levels. The effect was blocked after cutting the vagus nerve — the main connection between brain and gut. This suggests the gut-brain axis is being used by bacteria to affect the brain.
-This link was clarified in a study where bacterial metabolites (by-products) from fibre digestion were found to increase the levels of the gut hormone and neurotransmitter, serotonin. Serotonin can activate the vagus, suggesting one way your gut bacteria might be linked with your brain.
-There are many other ways gut bacteria might affect your brain, including via bacterial toxins and metabolites, nutrient-scavenging, changing your taste-receptors and stirring up your immune system.
-Even more intriguingly, in a study this year, gut microbiota samples from people with major depression were used to colonise bacteria-free rats. These rats went on to show behavioural changes related to depression.
-In rat pups, exposure to a stressor (being separated from their mums) changes their gut microbiota, their stress response, and their behaviour. Probiotics containing “good” strains of bacteria can reduce their stress behaviours.
-IBS is considered a “gut-brain disorder”, since it is often worsened by stress. Half of IBS sufferers also have difficulties with depression or anxiety.
-A new pilot study from Harvard University affiliates Benson-Henry Institute for Mind Body Medicine at Massachusetts General Hospital and Beth Israel Deaconess Medical Center found that meditation could have a significant impact for those with irritable bowel syndrome and inflammatory bowel disease. Forty-eight patients with either IBS or IBD took a 9-week session that included meditation training, and the results showed reduced pain, improved symptoms, stress reduction, and the change in expression of genes that contribute to inflammation.
With a well-balanced microbiome, a human being will:
Have at least one (possibly 2–3) well-formed, appropriately-colored, easily-passed bowel movement per day
Have little-to-no gas, bloating, reflux, heartburn or noise coming from the abdominal area
Have no pain or cramping in the abdominal area
Have little-to-no symptoms of systemic inflammation such as allergies, asthma, muscle pain, auto-immune disease, fibromyalgia, metabolic disorders, obesity, etc…
Buffer stress well without becoming overwhelmed
If any of the above is not true, likely the microbiome has become unbalanced along the way and is in need of fixing.
We are just at the beginning of comprehending the meaning of gut-to-brain microbiome interactions and what it ultimately means for host homeostasis including behavior. Recently, the role of bacteria in determining appetite and food preference was proposed [23], [24]. It is intriguing to speculate that microbes play a far larger role in normal homeostasis than previously imagined.
I suppose you could say, a happy gut is a happy you!
This is a really good video that summarises everything I have put down above!
