Gut microbiome

The gut microbiome is a complex community of trillions of microorganisms residing in the intestines.

99% of bacteria in the gut are anaerobes

Dysbiosis or an imbalance in this community is a common finding in CFS patients.

Pregnancy
Gut microbiota change dramatically from the first trimester to the third trimester of pregnancy. During the first trimester, there is an overrepresentation of 18 bacterial groups, mainly Faecalibacterium, a butyrate] producer that has been shown to improve symptoms of [[inflammatory bowel disease.

During the third trimester, populations of pro-inflammatory bacteria species such as proteobacteria and actinobacteria increase and there is a reduction in diversity. Populations of Faecalibacterium decrease. Overall bacterial load increases over the course of pregnancy.

Stress
There is growing evidence that the microbiome plays an important role in the stress response. Animals raised in a germ-free environment show an exaggerated HPA response to psychological stress which normalizes when Bifidobacterium infants is introduced. Escherichia coli can activate the HPA.

Stress also increases intestinal permeability.