Gut-Brain Axis: Irritable Bowel & Stress

by | | Gut Brain Axis


Due to the amount of neural tissue found in the digestive system many now refer to the gut as the second brain. Intuition, gut feeling and butterflies in the stomach all describe this.  Ask anyone with irritable bowel and they will the confirm that stress is a factor. 

Neurons don’t divide or regenerate. We begin losing them as soon as we are born. Slowing down this process is our goal because we can’t stop it. Brain plasticity describes how neurons can communicate and pass along information before its lost.

Lowered Brain Function Causing Digestive Distress

Most of the brain’s output occurs through the lower part of the brain stem. The vague nerve is also in this area and is responsible for innervating the whole digestive tract. When there is decreased activity in this area, there is also lower production of hydrochloric acid, pancreatic enzymes and bile. This lead to poor gut function overall including motility issues leading to constipation or diarrhea. Lower blood flow in the GI tract means weakened immune function and increases the risk of infection by pathogens and bacterial overgrowth.

How does Irritable Bowel lead to Leaky Brain?

What we are talking about here is irritable bowel or leaky gut. Chronic low grade infection increases inflammatory cytokines affecting the brain’s microglial cells. Do you see a vicious cycle? The brain’s microglia can’t turn down the inflammation the way other cells in the body can. Leaky brain contributes to leaky gut and vice versa. Around we go.

Gut Motility and Mood

Studies show constipation and depression are linked. The enteric nervous system in the gut is made of autonomic nervous tissue, intestinal microglia and lymphatic tissue. As mentioned earlier the vagal nerve stimulates peristalsis. Slower motility occurs when communication in impeded. For those suffering from irritable bowel with chronic diarrhea report recurrent anxiety.

The Journal of Clinical Psychiatry made the connection in 2001. They found 50-90% of irritable bowel patients reported psychiatric disorders including panic, anxiety, social phobia, PTSD and major depressive disorder. The immune cytokine model of depression has a lot of support. Basically it describes how inflammation is the root cause of most depression.

Brain Health on the Decline

IBS is the second cause of missed work after the common cold. Depression is on the rise 20% each year. Anxiety in young people is on the rise. Leaky brain leads to cognitive decline manifesting as memory problems, and not just in the elderly. More and more young people are being affected.

The brain requires oxygen and glucose. Alzheimer’s, Parkinson’s and other neurological conditions are being called diabetes of the brain. Chronic stress literally atrophies the brain. The link between cortisol and blood sugar confirms this. Blood flow to the brain means oxygen and glucose deliverability. In a stressed state this is inhibited.

A disrupted gut microbiome increases cortisol, inflammation, pain and brain-fog. It reduces your ability to feel pleasure, leads to depression and causes memory problems.

Functional Medicine Looks Deeper

Irritable bowel is not a real diagnosis. Testing the gut microbiome through SIBO and H.Pylori breath tests, stool tests and blood work give us an idea of what’s actually going on. Anticonvulsant drugs or antidepressants will never treat the underlying infection but conventional medicine isn’t getting it yet. In fact patients hear that it’s all in their head which is true in another sense.

Healthy Gut equals Happy Neurotransmitters

80% of Serotonin is produced in a healthy gut. Those with low serotonin experience cravings, impulsive behaviour and pain at four times the strength of those with normal levels.

SSRI’s are some of the most common antidepressants prescribed. They affect cortisol levels without looking at cortisol levels which is likely why they are only effective in some people.

Dopamine is what we feel when we eat a good meal that is satiating and take the time to enjoy it. This has been known as the root of health in many cultures for centuries.

Acupuncture and movement move blood, help inflammation and feel good. Enjoying food, expressing joy, and training your instincts are all ways to tend to brain health.

Evidence-based Studies

A growing body of evidence supports treating the gut when anxiety or depression.

Probiotics have been shown to decrease anxiety and help emotional processing.

Decreased stress is found in those who feed the good bacteria through fermented foods and prebiotics. After 3 weeks cortisol levels were lower. Anxiety was lower.

Related Posts