• Stressful life events have been shown to increase the risk of developing IBS

• There is a high occurrence of early life stress in IBS patients

• IBS is more prevalent among caregivers bearing the stress of caring for a seri- ously ill patient

• Mood disorders are predictive of developing functional gastrointestinal disorders such as IBS

The authors of the article The microbi-

ome: A key regulator of stress and neuroin- flammation stated it more succinctly: “Stress is…one of the most significant risk factors for irritable bowel syndrome.” In fact, the six contributing factors in IBS can each be linked as effects related to the stress response.

Linking the Stress Response to the Six Con- tributing Factors of IBS

Although the etiology, or underlying cause, of Irritable Bowel Syndrome is still not completely defined or understood, there are six factors that are considered to con- tribute to the condition: altered brain-gut function, abnormal gut motility, intestinal permeability, low-grade inflammation, visceral hypersensitivity, and psychosocial factors. There is also an intimate interplay between these factors, adding another layer of complexity to IBS symptoms.

1.Altered brain-gut function. As men- tioned previously, the enteric nervous system is the line of communication between the brain and gut. This com- munication influences the functioning of the digestive tract, including motility, sensory perception and digestive secre- tions. Chronic stress will blunt “rest and digest” activity, changing the messages between the brain and gut. When this communication is altered it can lead to abnormal gut motility and visceral hy- persensitivity, other contributing factors in IBS.

2.Abnormal gut motility. Irritable bowel syndrome is commonly subtyped based on the bowel habits, or gut motility traits, of the patient – IBS-C for consti- pation dominant, IBS-D for diarrhea dominant and IBS-M for mixed or alternating bowel habits. Altered brain- gut function can change the speed of movement through the digestive tract, leading to constipation, diarrhea, or a mix of both. Another driving factor of healthy gut motility is production of serotonin, or 5-HT. The neurotransmitter serotonin also helps regulate the HPA

24 ELM™ Maine - May/June 2018

axis indicating stress may affect sero- tonin production. This creates two po- tential pathways leading to IBS – altered gut-brain function and a complicated relationship between serotonin and gut motility.

3.Intestinal permeability. The lumen, or hollow interior, of the intestines is lined with a very thin layer of cells called epithelial cells. This layer creates a barrier to keep harmful substances out while selectively allowing nutrients and fluid into the body. Excessive stress has been shown to damage the epithelial layer, compromising this line of defense and causing intestinal permeability. The impaired protective barrier now allows larger substances through, such as un- digested food particles and pathogens, triggering immune and inflammatory responses and creating more stress on the body. Studies have not only shown increased intestinal permeability in IBS patients, but also indicated a positive correlation between intestinal perme- ability and symptom severity for IBS sufferers.

4.Low-grade inflammation. When there is damage to the intestinal lining, such as intestinal permeability, the immune system responds by releasing a type of immune cell called mucosal mast cells which may contribute to the progres- sion of IBS symptoms. Studies of IBS patients have indicated a positive corre- lation between the number of mucosal mast cells, the degree of intestinal per- meability, the amount of psychological stress and the severity of IBS symptoms. Additionally, these mast cells then trig- ger the release of pro-inflammatory sub- stances called cytokines, which include interleukin-6 (IL-6), Interleukin-1 beta (IL-1β), and tumor necrosis factor alpha (TNF-α). Chronic stress has been shown to increase pro-inflammatory cytokines which, in turn, activate the HPA axis and prolong the body’s stress response. This now potentially carves a path of increased damage, additional mast cells, more inflammation and intensi- fied IBS symptoms. In fact, studies have shown this to be the case – increased concentrations of both inflammatory and immune cells have been found in the intestinal tissue of IBS patients.

5.Visceral hypersensitivity. Visceral hypersensitivity is a term used to indicate pain in the abdominal region, a common complaint in IBS patients. The stress response has been shown

to contribute to this factor through the intimate interplay with the body’s inflammatory response. Stress creates inflammation by increasing proinflam- matory cytokines throughout the body. Stress has also been shown to activate the production of mucosal mast cells, further increasing pro-inflammatory cytokines. This excessive inflammatory response creates a chain reaction that eventually signals the gut via the enteric nervous system. Both the inflamma- tory gut signaling and stress-induced mast cells can then lead to increased visceral hypersensitivity and other IBS symptoms according to some studies. Additionally, serotonin also comes into play here. Serotonin not only regulates the HPA axis and gut motility, it normal- izes emotions and visceral perception as well. This may indicate there is a relationship between serotonin produc- tion, stress and gut motility that could influence abdominal pain perception in IBS patients.

6.Psychosocial factors. As mentioned earlier, mood disorders can predict the development of IBS. In fact, previ- ous anxiety and depression is a risk factor for developing IBS following an intestinal infection. Additionally, many observations – from epidemiology, empirical data and clinical observations – associate stressful life events with the onset, severity and persistence of IBS in certain subtypes, further endorsing the role stress plays in IBS sufferers.

This is not meant to overwhelm you with a lot of anatomy/physiology and sta- tistical information! In short, just remember there are several studies linking stress to each and every contributing factor of IBS symptoms. So, if you suffer from IBS or IBS- like symptoms, understanding your stress load will be a key step on your journey to better health.

Another key step is asking a question that still remains to be answered – does stress also affect the gut microbiota? Please stay tuned and pick up the next issue of ELMTM

Maine to find out!

Stephanie Walsh, CPT, CNTP, CEPC is a Certified Nutrition Therapy Practitioner, Certi- fied Eating Psychology Coach and Certified Personal Trainer. Contact Stephanie at (207)

730-2208 or email her: swalsh@theholis- www.theholisti- See ad on page 10.

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