Gut Dysbiosis. A dysfunctional gut microbiome

While we have an idea on what a healthy gut looks like we are also aware of what constitutes a dysfunctional gut that contributes to adverse health. This condition is called “Dysbiosis” where the microorganisms in the gut including the bacteria do not live in mutual accord, when the “good”, microorganisms are not successfully controlling the “bad” ones or disturbing the balance between “protective” versus “harmful” intestinal microorganisms.[1] It can also mean where an overgrowth of “pathobionts,” i.e., normally good bacteria[2], could negatively affect important functions of the microbiome ecosystem. Even lactobacillus in high concentrations are good for the large intestine and urogenital tracts of females but becomes a pathobiant if there are too many of them in the stomach (SBO) or small intestine where an overgrowth is linked with Small Intestinal Bacterial Overgrowth (SIBO). So even the so called “good bacteria” can become problematic and lead to dysbiosis if they are out of balance or in the wrong place.

The most important aspect of dysbiosis is that a loss of total microbial diversity which represents the first link in the chain of events leading to the development of local and body wide inflammation. Multiple human conditions have been associated with dysbiosis, including autoimmune and auto inflammatory disorders, such as allergies, cardio vascular, metabolic disorders (diabetes, obesity and non-alcoholic fatty liver disease), various cancers and inflammatory bowel disease such as Crohn's and ulcerative colitis (UC)[3], celiac disease[4], and neurological disorders including autism[5].

Once inflammation starts it appears that these opportunistic microorganisms are able to exploit the inflamed environment and expand their numbers[6] to become an even bigger problem.

There appear to be three types of dysbiosis that more often than not, occur together to create the problem. These include (i) loss of beneficial microbial organisms perhaps through the use of antibiotics, (ii) expansion of pathobionts or potentially harmful microorganisms as a result of too much processed foods and (iii) loss of overall microbial diversity. It is likely that dysbiosis encompasses all three of these manifestations at the same time to influence disease.[7]

The challenge is that the Dysbiotic microbial ecosystem can become resilient over time and may become hard to alter. In one study while dieting rapidly reversed the metabolic problems associated with a high fat diet, the dysbiosis in mice after a 4-week high fat diet persisted up to 21 weeks after returning to normal chow diet.[8] It did however change after 21 weeks.


[1] Milani et al., 2016.

[2] Chow et al., 2011.

[3] Baumler and Sperandio, 2016.

[4] Del Chierico et al., 2012.

[5] Konig et al., 2016.

[6] Spees et al., 2013.

[7] Petersen and Round, 2014.

[8] Thaiss et al., 2016.