The gastrointestinal system is an organ system which takes in food, digests it to extract and absorb energy and nutrients, and expels the remaining waste as feces. It consists of the esophagus, stomach, and intestines, and is divided into the upper and lower gastrointestinal tracts.
Evidence of gastrointestinal dysfunction in CFS[edit | edit source]
Dysbiosis[edit | edit source]
There is strong evidence that dysbiosis or an imbalance in the microbial ecology of the gut plays a role in the symptoms of ME/CFS. On average, ME/CFS patients have lower levels of Bifidobacteria, Escherichia coli and higher levels of aerobic bacteria, in particular Enterococcus and Streptococcus species. The latter produce D-lactate, a form of lactic acid only produced by non-human cells that is poorly metabolized in humans. D lactate is associated with a wide variety of cognitive and neurological symptoms, such as in patients who suffer from D-lactic acidosis. A study found that higher levels of enterococcus bacteria in CFS patients were associated with more severe neurological and cognitive dysfunction.
CFS patients may suffer from small intestinal bacterial overgrowth (SIBO) at high rates.
One hypothesized consequence of dysobiosis is an overproduction of hydrogen sulfide (H2S) by pathogenic bacteria. H2S can inhibit mitochondrial respiration by blocking cytochrome c oxidase.
A study of Norwegian and Belgian patients found significantly decreased proportions of Firmicutes genera Holdemania and increased proportions of Bacteroidetes genera Alistipes in the Norwegian but not the Belgian sample. Significantly increased proportions of Firmicutes genera Lactonifactor were found in both.
Intestinal permeability[edit | edit source]
In a healthy digestive tract, the intestinal walls provide a tight, selective barrier to allow the absorption of nutrients prevent the entry of bacteria or pathogens. However, in CFS patients, there is evidence of increased intestinal permeability or "leaky gut." Intestinal permeability can allow for the translocation of bacteria across the mucosal lining and inside the blood stream.
One study found higher levels of serum IgA and IgM against lipopolysaccharides (LPS), a major component of the outer membrane of gram-negative bacteria, indicating translocation. Serum IgA was significantly correlated to the severity of illness.
Malabsorption[edit | edit source]
Learn more[edit | edit source]
See also[edit | edit source]
References[edit | edit source]
- Logan, Alan C; Venket Rao, A; Irani, Dinaz (Jun 2003). "Chronic fatigue syndrome: lactic acid bacteria may be of therapeutic value". Medical Hypotheses. 60 (6): 915–923. doi:10.1016/S0306-9877(03)00096-3. ISSN 0306-9877.
- Sheedy, John R.; Wettenhall, Richard E. H.; Scanlon, Denis; Gooley, Paul R.; Lewis, Donald P.; McGregor, Neil; Stapleton, David I.; Butt, Henry L.; DE Meirleir, Kenny L. (Jul 2009). "Increased d-lactic Acid intestinal bacteria in patients with chronic fatigue syndrome". In Vivo (Athens, Greece). 23 (4): 621–628. ISSN 0258-851X. PMID 19567398.
- "High-throughput 16S rRNA gene sequencing reveals alterations of intestinal microbiota in myalgic encephalomyelitis/chronic fatigue syndrome patients". Anaerobe. 22: 50–56. Aug 1, 2013. doi:10.1016/j.anaerobe.2013.06.002. ISSN 1075-9964.
- Maes, Michael; Mihaylova, Ivana; Leunis, Jean-Claude (Apr 2007). "Increased serum IgA and IgM against LPS of enterobacteria in chronic fatigue syndrome (CFS): Indication for the involvement of gram-negative enterobacteria in the etiology of CFS and for the presence of an increased gut–intestinal permeability". Journal of Affective Disorders. 99 (1-3): 237–240. doi:10.1016/j.jad.2006.08.021. ISSN 0165-0327.
chronic fatigue syndrome (CFS) - A controversial term, invented by the U.S. Centers for Disease Control, that generally refers to a collection of symptoms as “fatigue”. There have been multiple attempts to come up with a set of diagnostic criteria to define this term, but few of those diagnostic criteria are currently in use. Previous attempts to define this term include the Fukuda criteria and the Oxford criteria. Some view the term as a useful diagnostic category for people with long-term fatigue of unexplained origin. Others view the term as a derogatory term borne out of animus towards patients. Some view the term as a synonym of myalgic encephalomyelitis, while others view myalgic encephalomyelitis as a distinct disease.
membrane - The word "membrane" can have different meanings in different fields of biology. In cell biology, a membrane is a layer of molecules that surround its contents. Examples of cell-biology membranes include the "cell membrane" that surrounds a cell, the "mitochondrial membranes" that form the outer layers of mitochondria, and the "viral envelope" that surrounds enveloped viruses. In anatomy or tissue biology, a membrane is a barrier formed by a layer of cells. Examples of anatomical membranes include the pleural membranes that surrounds the lungs, the pericardium which surrounds the heart, and some of the layers within the blood-brain barrier.