Your immune system is a powerful system that helps to take care of you. It protects you from infection, injury and even psychological distress. The nervous system and the immune system communicate closely - the immune system gets really involved if you're facing adversities. Chronic and traumatic stress can lead to alterations in its activity.

Small protein molecules called cytokines create a mobile protective system throughout your body, and many cells and organs make them. Although simplistic for a complex network, the balance between your pro- and anti- inflammatory cytokines revolves around a set point that's crucial to your physical and psychological health. Pro-inflammatory increases can lead to anxiety and depression because of cytokines influence on microglia - these are the immune cells of the brain.

Chronic and traumatic stress can inhibit the vagus nerve and this has adverse effects on the gastrointestinal tract and the microbiota. Dysbiosis is a disruption to the balance of the microbiota and can lead to an increase in inflammatory cytokines. This can be the root cause gastrointestinal disorders such as irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD), which are both characterised by dysbiosis

The anti-inflammatory capacities of the vagus nerve can help restore balance to the nervous system, the immune system and the gut-brain axis. This can happen through several different pathways. When the vagus nerve is stimulated it releases the neurotransmitter acetylcholine which is used throughout your entire nervous system, including your enteric nervous system (your belly brain). Acetylcholine decreases your heart rate, slowing your physiology after challenges. This can play a key role to how you cope with and recover from stressful events.

The vagus nerve is the main connection between the gut and the brain. It has anti-inflammatory properties both through its afferent (from the gut to the brain) and efferent (brain to gut) fibers. Its influence on the gastrointestinal system improves motility and acts to increase peristalsis in the stomach and the amplitude of digestive contractions. This can improve gut function and the balance of the microbiota. Its release of acetylcholine ensures rogue immune cells stop over-reacting to the microbiota and their metabolites in the gut.

Chronic and traumatic stress can shift your immune system to be overreactive causing inflammation and this can cause chronic pain, anxiety and depression. It can also go the other way: the immune system can become under-responsive as well. Under chronic stress, antibodies are less effective at identifying foreign microbes and your defences come down. For the short-term these changes to the immune system makes the body efficient at dealing with stress, but for the long term it can lead to chronic conditions.

When we move away from the idea that the body is a machine that has separate parts, towards viewing it as a highly interconnected ecological system, we see how chronic health conditions can arise and the ways they can improve. The vagus nerve is the bridge between the brain and the gut, facilitating two-way communication. The health of your gut is reflected in your psychological well-being, and vice versa. Its also interconnected to your immune, endocrine and cardiovascular systems.

Low vagal tone can be seen with chronic pain, digestive issues, allergies, autoimmune conditions, depression and anxiety. Targeting the vagus nerve and promoting its anti-inflammatory properties helps restore balance in the microbiota-gut-brain axis. High vagal tone leads to improvements in our emotional health as well as our physical health.

You can learn the interventions that help improve the functioning of the vagus nerve, in my 3 hour Vagus Nerve Masterclass.