The brain-gut axis and its role in chronic pain

Part 2 of Coping with Pain series: Gut- Brain Axis

In the world of health and wellness, there has been an increased focus on the brain-gut axis—a bidirectional communication network between the central nervous system (CNS) and the enteric nervous system (ENS) of the gastrointestinal tract. It regulates a number of bodily functions, including pain and the body's response to stress. This axis involves neural, metabolic, endocrine, and immune signals, with a significant role played by the gut microbiome. The microbiome refers to the collection of trillions of microorganisms that live in and on our bodies, playing a crucial role in maintaining our overall health, digestion, immune system, and even mental well-being. The vagus nerve, one of the major nerves running through the body, also plays an important part in this communication, sending signals from the gut to the brain and vice versa.

Function in pain regulation

The brain-gut axis plays a central role in modulating pain perception, especially in chronic conditions. Signals from the gut can affect how pain is processed in the brain. For example, stress and anxiety can heighten pain perception through this axis. In people with chronic pain, an imbalanced brain-gut axis often exacerbates symptoms, creating a feedback loop where gut dysfunction increases pain sensitivity and vice versa .

Function in stress response

The brain-gut axis is vital to the body's stress response, primarily via the

hypothalamic-pituitary-adrenal (HPA) axis. When the body experiences stress, the HPA axis is activated, leading to the release of cortisol and other stress hormones. These hormones affect gut motility, permeability, and microbiome composition, contributing to inflammation and affecting overall health .

Gut health and chronic pain

Emerging research suggests that gut health can be closely tied to chronic pain conditions and inflammatory diseases. An imbalance in gut microbiota can contribute to inflammation and immune system dysregulation, both of which are linked to heightened pain sensitivity. Inflammation within the gut can impact neural pathways, increasing the intensity and duration of chronic pain. Furthermore, a healthy microbiome helps maintain the integrity of the gut barrier, reducing systemic inflammation and potentially mitigating chronic pain.

Exploring the role of the vagus nerve

Central to brain-gut communication is the vagus nerve, the longest cranial nerve in the body, running from the brain stem through the neck and down to the abdomen, sending sensory information from the gut to the brain and relaying motor signals back from the brain to the gut. The vagus nerve regulates essential functions such as digestion, immune responses, and heart rate.

When stress or anxiety activates the sympathetic nervous system (the "fight or flight" response), signals are sent through the vagus nerve to the gut, potentially disrupting normal gut function. This can lead to inflammation or changes in the gut microbiome, which may, in turn, send distress signals back to the brain, heightening the perception of pain.

On the other hand, activation of the parasympathetic nervous system (the "rest and digest" response), mainly through the vagus nerve, can reduce pain perception. This activation promotes relaxation, reduces inflammation, and helps restore normal gut function.

The balance of signals sent through the vagus nerve can either amplify or diminish pain, illustrating how critical this nerve is in both the perception and management of pain conditions.

How gut inflammation exacerbates chronic pain conditions

Inflammation can be a huge factor in the development and worsening of chronic pain conditions, particularly when it originates in the gut. When the gut is inflamed, it can affect not only local tissues but also contribute to systemic inflammation, leading to or worsening conditions such as:

● Irritable bowel syndrome (IBS): Gut inflammation is a key feature in IBS, particularly in more severe cases. When the gut lining becomes inflamed, it can trigger widespread inflammation and immune responses that heighten the perception of pain. Inflammation in the gut also alters gut motility and increases sensitivity, leading to abdominal pain and discomfort.

● Fibromyalgia: Though fibromyalgia is characterized by widespread musculoskeletal pain, there is increasing evidence that gut health can be a factor. Many people with fibromyalgia also suffer from IBS, and may experience systemic inflammation caused by an imbalance in gut bacteria. Chronic inflammation in the gut can send pain signals via the brain-gut axis, amplifying the overall pain response throughout the body.

• Arthritis: Both rheumatoid arthritis and osteoarthritis may be linked to inflammation that

starts in the gut. Certain gut bacteria have been found to provoke immune responses that attack joint tissues, contributing to the swelling, stiffness, and pain experienced in arthritis.

Common triggers of gut inflammation

Gut inflammation can stem from several key triggers that affect both gut health and overall well-being:

● Processed foods: Diets high in processed foods, sugar, and unhealthy fats can disrupt gut bacteria balance, promote harmful bacterial growth, and increase intestinal inflammation. These foods can also make the gut more permeable, allowing harmful substances to enter the bloodstream and trigger systemic inflammation.

● Stress: The gut-brain axis becomes dysregulated under chronic stress, leading to both gut dysfunction and an amplification of pain signals. Stress hormones like cortisol can become harmful when elevated over long periods, and persistent stress also causes immune cells in the gut to release pro-inflammatory cytokines, which exacerbate gut inflammation and pain perception in general.

• Medications: Certain medications, such as nonsteroidal anti-inflammatory drugs

(NSAIDs) like ibuprofen, can irritate the gut lining and increase inflammation.

Long-term use of these drugs can worsen gut health and chronic pain by contributing to gut permeability. Antibiotics can also disrupt the gut microbiome, leading to further inflammation.

Understanding and addressing these triggers can help manage chronic pain and improve gut health.

How to improve the gut-brain connection

Now that you know about the gut-brain axis, you can nurture its function. By prioritizing a balanced diet, herbal support, and stress management, you have the power to restore proper function to the brain-gut axis and lower inflammation, ultimately reducing pain.

Dietary interventions to improve gut health

● Probiotics: Probiotics are beneficial bacteria that help restore balance to the gut microbiome, which is helpful for reducing inflammation and improving digestion. Including probiotic-rich foods like sauerkraut, kefir, yogurt, kimchi, and miso can help strengthen the gut lining and support overall gut health. Probiotic supplements can also be effective.

● Fibre-rich foods: A diet high in fibre supports healthy digestion and nourishes beneficial gut bacteria. Soluble fibres, found in foods like oats, apples, chia seeds, and legumes, can promote regular bowel movements and reduce inflammation. Insoluble fibres, found in whole grains, nuts, and vegetables, aid in gut motility and help to prevent constipation. Fibre also helps prevent the development of leaky gut, a contributor to systemic inflammation and chronic pain.

● Prebiotics: Prebiotic foods, such as garlic, onions, bananas, and asparagus, feed the healthy bacteria in the gut, encouraging their growth and maintaining balance. This helps improve digestion and reduce gut inflammation, which can ease chronic pain by reducing pain signals sent to the brain. (Note that some foods in the FODMAP group, such as onion and garlic, may not be well-tolerated by those with IBS, so add them in moderation until you know how your body handles them.)

Herbal support for gut health

There are so many herbs that can aid in nourishing the gut-brain connection, but these are a few favourites:

● Ginger root (Zingiber officinale): Ginger has powerful anti-inflammatory and digestive properties. It can help reduce gut inflammation and improve motility, making it beneficial for conditions like IBS. Ginger is also effective in reducing nausea, bloating, and abdominal discomfort associated with poor gut health.

● Peppermint (Mentha piperita): Peppermint is well-known for its ability to soothe digestive issues and relax the muscles of the GI tract, which can relieve cramping and bloating. Peppermint oil is commonly used for managing IBS symptoms and has been shown to reduce abdominal pain.

● Marshmallow root (Althea officinalis): Marshmallow root is a soothing demulcent herb that helps protect the gut lining and reduce inflammation. It can be particularly beneficial for individuals with IBS or acid reflux, as it promotes the healing of the gut lining and supports healthy microbiota.

● Turmeric root (Curcuma longa): A renowned anti-inflammatory for the musculoskeletal system, it should come as no surprise that turmeric also has the same effect on the GI tract.

● Holy basil (Ocimum sanctum): As an adaptogenic herb, holy basil can help bolster the body’s tolerance to stress, and help it recover and heal faster.

● Ashwagandha root (Withania somnifera): Ashwagandha is another adaptogen that can help improve the function of the axis and also reduce the negative effects of chronic stress.

This is by no means an exhaustive list! Herbs with adaptogenic, demulcent, antispasmodic and anti-inflammatory actions can be especially useful in promoting a healthy gut.

Stress management techniques for gut health and pain reduction

Meditation: Mindfulness meditation has been shown to reduce both stress and chronic pain. Regular meditation helps calm the nervous system and reduce the release of stress hormones like cortisol, which can damage the gut lining and promote inflammation.

Yoga: Yoga combines movement, breathwork, and mindfulness, making it an excellent practice for improving both gut health and pain levels. Certain yoga poses help stimulate digestion and improve gut motility, while the relaxation aspect helps reduce stress and inflammation.

Breathwork: Deep breathing exercises can activate the parasympathetic nervous system (the body's "rest and digest" system) through the vagus nerve. This reduces the body’s stress response, promoting relaxation in the gut and decreasing inflammation. Regular breathwork can improve digestion, ease gut-related pain, and lower overall pain sensitivity.

In conclusion

Supporting your gut-brain axis through diet, herbal supplements, and stress management can have a significant impact on reducing chronic pain. By addressing the root causes of gut dysfunction and inflammation, individuals can break the cycle of pain and restore balance to the brain-gut axis. Incorporating probiotics, fiber, gut-soothing herbs, and stress-reducing practices like meditation and yoga can provide relief and promote long-term health.

Watch for Part 3 of this 3 part Series on Coping with Pain the week of October 21/24

Guest Author: Danielle Brost is a certified herbal practitioner, offering online personalized herbal consultations and wellness plans. Based in Victoria, BC, her passion is to empower clients to "lessen their limits" and live healthier, more enjoyable lives. She can be reached through her website at https://www.lilyoftheforest.com/