Ken Lassesen's model

Ken Lassesen is a mathematician and software engineer who first became ill with chronic fatigue syndrome in 1972, then 2001, 2012. Each recovery was connected to a treatment that would have altered gut microbiome (although that was not the intended target for the first two recoveries). He believes the symptoms of CFS are caused by gut dysbiosis because it meets Osler criteria -- the simplest model that is consistent with all of the observations. He outlines his model in a paper.

Theory
Lasses theorizes that CFS is caused by a shift in gut bacteria. .  This shift can have many causes including stress, viral infection, bacterial infection, and immunization.

The shift in gut bacteria also alters host ability to extract and process nutrients, leading to deficiencies in key amino acids, vitamins, and minerals.

Variation between patients in the population of gut bacteria explains the heterogeneity of symptoms.

Gut Bacteria Shifts Seen
The model is based on the shifts reported in 1998 and 2001 at Australian CFS/ME Clinical and Scientific Meeting. He has produced a matrix showing how certain anti-pathogens impacts the 6 key bacteria shifts reported in the literature. Scoring done by 1 for each EFFECTIVE in high (good) and -2 for each EFFECTIVE in low (the harm is more significant than the good). Postive scores are desired

Hypercoagulation
Lassesen also emphasizes hypercoagulation as a major factor in CFS, which in his case is at least in part genetic.

Treatment
Lasses theorizes that a variety of probiotics may be of benefit in correcting the dysbosis along with herbal and pharmaceutical antibiotics. The success of treatment and the specific strains most likely to be effective may depend in part on the specific profile of a patient's gut bacteria, which is impossible to fully characterize under existing measurement techniques.

However, Lassesen cites several small studies indicating CFS patients may have low populations of bifidobacterium, lactobacillus and escherichia coli.

He recommends strict avoidance of any lactobacillus acidophilus containing probiotics or yogurts and other lactic acid producing strains. And he recommends the use of bifidobacterium-only products as well as Align, Mutaflor, Miyarisan and Prescript Assist.

Evidence
While there has a been no research on the application of Lassesen's theory in CFS patients, there is some research in CFS and more extensive research in irritable bowel syndrome supporting aspects of his approach. In early 2016 a web-based study will begin through Mendus wherein ME/CFS patients can participate in a study that will address aspects of Lassesen's (and others) thoughts concerning gut dysbiosis.

Chronic fatigue syndrome
One study found increased d-lactic acid intestinal bacteria in CFS patients.