As discussed in our introductory article on digestive health, leaky gut is a potential underling cause or mediator of chronic fatigue syndrome.
What Is Leaky Gut?
To answer this we first need some basic understanding of the digestive system.
From the lower oesophageal sphincter to the anus, the gastrointestinal tract has a single contiguous layer of cells that separates the inside of the body from the external environment. Separation is important as there are a wide variety of environmental agents in the lumen (the inside space of the intestines) that can initiate or perpetuate mucosal inflammation if they cross the epithelial barrier (the lining of the gut). These environmental agents include bacteria, fungi, viruses and undigested food particles. While the epithelial lining of the intestine plays a critical role in preventing access of these agents, it is not the only component. Also important are secreted products such as immunoglobulin, mucous, defensins, and other antimicrobial products (Arrieta et al., 2006)
Put simply the lining of the digestive tract, through various mechanisms, acts as a selective barrier to the content of the digestive system. If these environmental agents are able to travel across the epithelial barrier (the lining of the gut) then an immune and inflammatory response may follow.
Innate immune functions are carried out mainly by goblet cells and paneth cells, highly specialized epithelial cells with secretory functions.
Goblet cells release mucins, which give rise to a viscous mucous layer on the gut wall, hampering the access of bacteria to the epithelial surface. I often describe this as imagining your digestive tract as a hose pipe and running prick stick down the inside. The prit stick represents the mucus that lines the digestive tract.
Paneth cells in contrast release granules containing anti-microbial peptides. These anti-microbial peptides are thought not only to kill bacteria; their diversity and regulated expression patterns are believed to actively shape the microbial communities present within the gut lumen. Anti-microbial peptides and mucins together form a thick bactericidal mucous layer which hampers access and survival of bacteria adjacent to the epithelium.
Secretory IgA (SIgA) serves as the first line of defense in protecting the gut lining from enteric toxins and pathogenic microorganisms. Through a process known as immune exclusion, SIgA promotes the clearance of antigens and pathogenic microorganisms from the intestinal lumen by blocking their access to receptors that are found on the gut lining, entrapping them in mucus, and facilitating their removal by peristaltic and mucociliary activities.
Besides its important functions in generating a barrier against the external environment, the intestinal epithelium is also the most vigorously self-renewing tissue of adult individuals. Intestinal epithelial cells are generated by proliferating stem cells at the bot-tom of the Crypts of Lieberkühn. During their short lifetime of 4–5 days, intestinal epithelial cells move up towards the intestinal surface (Günther et al., 2014).
Intestinal tight junctions are selectively-permeable, and intestinal permeability can be increased physiologically in response to luminal nutrients or pathologically by mucosal immune cells and cytokines, the enteric nervous system, and pathogens.
Compromised intestinal barrier function is associated with an array of clinical conditions, both intestinal and systemic.
What Causes Leaky Gut?
- NSAID Therapy
- IBD (chron’s Disease)
- Small Intestinal Bacterial Overgrowth
- Celiac Disease
- Food Allergy
- Chronic Alcoholism
- Strenuous Exercise
- Increasing Age
- Nutritional Depletion
- Systemic Inflammation
- Deficiencies in hormones such as testosterone, estrogens, thyroid.
- High blood sugar
- Infections (bacterial, parasite, viral)
- Gut brain axis – head trauma, vagus nerve complications • Chronic Stress
Does leaky gut cause fatigue?
The results show that normalization of the IgA and IgM responses to translocated LPS may predict clinical outcome in CFS (Maes, 2008)
Some studies certainly suggest in a subgroup of individuals with CFS that optimising the environment of the digestive system may lead to significant improvement if not resolution of their symptoms.
Optimising Digestive Health
Optimising digestive health needs to be personalised based on the current state of the system. There are also discussions to be had about some of the most common strategies, such as the FODMAP diet.
For some general guidelines around supporting digestive health see our article here.