Another study came out in which another syndrome is linked with a lower diversity of the gut microbiome. This time the syndrome is chronic fatigue syndrome (CFS).

CFS is a condition in which the individual experiences fatigue which cannot be alleviated by bed rest; even more, mental or physical activity will make it worse. Affected individuals will display a wide range of symptoms including joint and/or muscle pain, tiredness lasting for more than 24 hours after exertion, headaches, .. Many also report gastrointestinal discomfort and some have irritable bowel syndrome or other complaints.

In order to address these complaints, some studies have included probiotic therapy (orally or rectally administered) or have measured the levels of inflammation in the plasma or cerebrospinal fluid.

Giloteaux et al measured specific molecules that indicate that microorganisms have travelled from the gut (i.e. outside of the body) to the inside (i.e.  into the blood) in 39 control subjects and 49 subjects with CFS. These molecules included lipopolysaccharide LPS; which is component of the cell-membrane of gram-negative bacteria) and related molecules such as LPS-binding protein and the LPS receptor; a protein whose levels rise during inflammation (C-reactive protein); and intestinal fatty acid binding protein (I-FABP), which gives an idea about the integrity of the intestinal lining (integrity).

In summary, their results indicated that patients with CFS had higher levels especially of molecules that are synthesized during inflammation, e.g. LPS-like molecules and C-reactive protein.

They also found that the microbial diversity (the number of different bacterial species) in the stool of the subjects with CFS was lower than that of the control subjects. Two examples of the bacteria whose numbers were reduced in people with CFS included (but there were others as well):

• Faecalibacterium, a member of the Ruminococcaceae was significantly underrepresented in the ME/CFS population (also in patients with inflammatory bowel disease and ulcerative colitis). Interestingly, these bacteria produce anti-inflammatory molecules such as butyrate, which protects the intestines.
• Bifidobacterium was also reduced, it is widely known as a probiotic. Its administration to people with ME/CFS showed that it reduced the levels of C-reactive protein, which is produced during inflammation.

Together these data suggest that disruption of the intestinal flora may contribute to the symptoms and severity of the CSF and the use of agents that reduce local inflammation, restores the intestinal immune system and rebalances the gut microbiome will help to reduce the symptoms of the disease in at least some of those affected.