Your Gut and Stress:Part 3
Last week I got into the link between our gut and our brain, the role it plays in our mood, and how the vagus nerve impacts our pain response. In this blog I’ll discuss more specifically, the role stress plays in pain, particularly the toll of prolonged stress. I’ll also discuss the relationship between the gut and the stress response and the relationship between the gut and the relaxation response.
The link between our stress response and pain
Stress and chronic pain have been referenced as the two sides to the same coin. Pain and stress are protective mechanisms associated with our “fight or flight” response (sympathetic nervous system) and are known to cause negative changes in our physical, emotional and mental health when they become chronic.
The body is well equipped to deal with acute (short lived) stress, but when stress becomes constant and chronic it can become very damaging.
To better understand this it helps to understand two key hormones that get released when we are stressed.
Cortisol – Appropriately called the “stress hormone” cortisol is a steroid hormone made in the adrenal cortex. It is secreted by the adrenal glands into the body and its release is triggered by stress and blood sugar levels. Cortisol is an essential hormone for human health as it helps regulate metabolism and in times of stress is released to support the body in its response.
One way it does this is slowing body processes that are not essential to survival.
The challenge is that prolonged elevated cortisol levels during a persistent state of stress can comprise our immune system, increase our blood pressure and in turn lead to serious mental and physical health problems.
Adrenaline – Like cortisol, this is another hormone released by the adrenals during periods of stress. Although adrenaline and cortisol come from two separate parts of the gland - cortisol from the outer part and adrenaline from the inner part - they both play a huge role in the body’s reaction to stress.
Adrenaline helps the body respond almost instantaneously in acute stressful situations, whereas cortisol’s effects and responses in the body take a little more time.
Adrenaline’s role is activating a lot of the physiological changes in our body during fight or flight such as increased heart rate, increased respiratory rate etc.
An excess of both these hormones can make you feel jittery, anxious, unable to sleep, irritable and lead to adrenal exhaustion. A chronic deficiency can also cause mental health problems however physical symptoms are energy depletive and can leave you feeling sluggish and fatigued, even after sleep.
As you can see, chronic stress, causes an unfavorable hormonal response in the body.
Prolonged Stress: the toll on you, your weight and your pain
Chronic pain is considered a state of prolonged stress in your body, where our body remains in a persist state of high alert to danger, threats and perceived threats.
So any type of pain that is ongoing adds insult to injury by causing a chronic stress response.
Specifically, a chronic stress response can:
Increase the secretion of glucose from our liver, which increases our blood sugar levels
Decrease the hormones responsible for removing excess glucose from your blood – insulin
Cause glucose to be stored as fat
Decrease the ability to clear excess hormones from our liver, leading to increasing circulation of unnecessary hormones like cortisol, oestrogen etc.
Increase our appetite and attention to food (this is due to the fact that “fight or flight” and prolonged stress usually meant famine or food shortage)
Cause weight gain
Alter the gut microbiome, which can in turn, perpetuate a heightened stress response and further depress the immune system
Some additional side effects of prolonged stress include imbalances to our sex-hormones, such as oestrogen dominance; changes to our hypothalamic pituitary adrenal (HPA) axis; and changes to our thyroid and growth hormones; all of which have an impact on healthy weight, metabolism and weight-loss.
The relationship between the gut and the stress response
The gut plays an important role in our stress response; when exposed to stressful stimulus, the hypothalamic pituitary adrenal (HPA) axis, and the sympathetic nervous system are activated to maintain balance in the body.
Researchers have identified that “gut microbiota can play a critical role in the development and regulation of the HPA response to stressors”.
The HPA axis is central to our stress response and is responsible for the release of hormones (including adrenaline and cortisol) from our hypothalamus, pituitary and adrenal glands.
The gut and gut microbiome play an important role in regulating levels of cortisol, which are released by the HPA; there are ongoing studies looking at the link between specific gut microbiome and the HPA axis and how this can be used in chronic stress states.
Studies have also found that stress negatively alters the gut microbiome and those alterations, in turn, further cause a stress response in the body. In other words the gut is both impacted by, and has an impact on, our stress response.
This raises the question: could we modify our body’s stress response, and pain response, by targeting the microbiome?
For example, there’s been some research that looked at how different microbial strains might target specific conditions, like stress and pain.
Another interesting approach to pain management and the stress response deals with neurotransmitters and the gut, and whether we can modulate specific neurotransmitters and/or their related pathways.
As I mentioned in last weeks blog many of our neurotransmitters are made in the gut, including 90% of our serotonin, which plays an important role in the processing of pain.
Some research has even demonstrated that supplementation of specific probiotics can change levels of neurotransmitters, or affect the pathways of these neurotransmitters.
The relationship between our gut and relaxation response
I’m going to overlap with last weeks blog a little, but I think it’s important to take a longer look at the vagus nerve and the crucial role it has in engaging the parasympathetic nervous system, which is part of your autonomic nervous system.
The parasympathetic nervous system is the opposite of your sympathetic nervous system or you “fight or flight” response. Also called “rest and digest”, parasympathetic nervous system function is your body’s relaxation response.
And I consider the vagus nerve to be the key player in mediating this response.
Some vagus nerve facts: The word “vagus” in Latin means wandering, which is exactly what this nerve does, running from our brain stem to our colon. It connects a vast majority of our major organs, particularly those which make up our gut, and allows communication between them and our brain.
It also consists of efferent (motor) pathways, which are involved with stimulating the muscles within our mouth and throat, stimulating our heart and stimulating the involuntary movements within our gut which allow food to move through.
Because the vagus nerve is largely responsible for the mind-body connection (gut-brain axis) it plays a crucial role in our thoughts, and feelings and our physical reactions to stress.
In fact stimulating the vagus nerve helps trigger the relaxation response, reducing heart rate and blood pressure.
As we breathe slowly and deeply sensory nodes in our lungs send information to our brain via the vagus nerve. The brain then sends a message (also via the vagus nerve) quelling the stress response and mitigating pain.
It has long been suggested that harnessing the power of our parasympathetic nervous system may reduce the symptoms associated with chronic pain. Because the body can’t stress and rest at simultaneously, by activating the relaxation response you effectively deactivate the stress response.
And the vagus nerve is a powerful way to initiate the relaxation response.
When your sympathetic nervous system ramps up the fight or flight response—pouring cortisol and adrenaline into your body—the vagus nerve can tell your body to calm down by sending “instructions” to release enzymes and proteins like prolactin, vasopressin, and oxytocin, which calm you down.
The “tone” of the vagus nerve is key to activating the parasympathetic nervous system. “Vagal tone” refers to the strength of the vagus nerve.
Vagal tone is measured by tracking
your heart-rate alongside your breathing rate. The bigger the difference between your inhalation heart-rate and your exhalation heart-rate, the higher your vagal tone. High vagal tone essentially means that your body can relax faster after stress.
High vagal tone also means better blood sugar regulation and improved digestion via better production of stomach acid and digestive enzymes. It’s also associated with better mood, less anxiety and more stress resilience.
I think one of the most interesting roles of the vagus nerve is that it essentially reads the gut microbiome and initiates a response to modulate inflammation based on whether or not it detects pathogenic versus non-pathogenic organisms.
This is part of why the gut microbiome affects your mood, stress levels and overall inflammation.
Low vagal tone on the other hand is associated with all the stuff you don’t want like increased risk of cardiovascular conditions and strokes, depression, diabetes, chronic fatigue syndrome, cognitive impairment, and much higher rates of inflammatory conditions including all autoimmune diseases like rheumatoid arthritis, IBD, endometriosis, autoimmune thyroid conditions, lupus and so on.
It is also associated with anxiety, a much higher stress response, and an increased sensitivity to pain.
To some degree you are genetically predisposed to have a high or low vagal tone, but that doesn’t mean that you can’t improve it. The vagus nerve is similar to a muscle – we can improve its strength through exercising it.
Research has found that gargling, diaphragmatic breathing, laughing, singing, humming, yoga, tai chi, cold-water or contrast showers and cold-water swimming are all activities that can improve the health and strength of the vagus nerve.
Improved vagus nerve health can-literally- change how your brain perceives pain.
Pain perception can also be improved by examining the intersection of the vagus nerve, neurotransmitters and our the. As I mentioned, the vagus nerve connects the gut and brain, through the gut-brain axis. It communicates information from the gut to the brain using neurotransmitters (such as serotonin and glutamate) and gut hormones, all of which play a vital role in sleep, mood, pain, stress and hunger. This is why improving the health of the gut through diet, probiotics and even potentially fecal microbial transplantation(FMT), can improve the gut-brain axis, and therefore, impact our perception of pain.
It’s also worth mentioning that improving vagus nerve function may have an impact on inflammation within the body. Inflammation plays a role in neuroinflammation (a process which affects the health and disease of the nervous system by regulating the development, maintenance and sustenance of brain cells and their pathways) which is considered one of the drivers of chronic pain and central sensitization.
Stress and chronic pain are referred to as two sides of the same coin and both are protective mechanisms associated with the sympathetic nervous system (fight or flight)
Since the body cannot simultaneously exist in both sympathetic and parasympathetic states, one way to manage pain is to engage Your parasympathetic nervous system function.
The gut plays an important role in our response to stress. Gut microbiota can play a critical role in the development and regulation of the HPA response to stressors. Neurotransmitter modulation and targeted probiotic therapies can positively impact the gut and our pain response.
The vagus nerve is key in engaging the relaxation response and stimulating it, can help alleviate chronic pain.
Ways to improve vagal tone include gargling, diaphragmatic breathing, laughing, singing, humming, yoga, tai chi, cold-water or contrast showers and cold-water swimming.