Table 1.

Physiological and metabolic processes influenced by the human microbiome.

Processes	Reference
Enzymatic pathways, glycosaminoglycan degradation	Abubucker et al., 2012; Koppel et al., 2017
Energy metabolism (short chain fatty acids, glucose)	den Besten et al., 2013; Hartstra et al., 2015; Sonnenburg and Bäckhed, 2016
Neurotransmitter production	O’Mahony et al., 2015; Yano et al., 2015; Savidge, 2016
Vitamin absorption	Magnúsdóttir et al., 2015
Regulation of bile acid metabolism, (deoxycholic and lithocholic acids, bile salts)	Fiorucci and Distrutti, 2015; Weiss and Hennet, 2017
Endocrine and gut hormone regulation	Neuman et al., 2015; Fukui et al., 2018
Adaptive immunity, mucosal and systemic immunity	Thaiss et al., 2016; Desselberger, 2018
Cell proliferation, mucosal barrier protection, inflammation	Morgan et al., 2012; Blander et al., 2017; Schirmer et al., 2018
Protection against pathogens	Zeng et al., 2016; Zhang et al., 2018
Vascularization, tri-ethylamine associated atherosclerosis, tri-ethylamine N-oxide (TMAO) production	Karlsson et al., 2012; Tang et al., 2013; Tang and Hazen, 2014
Bone mass	McCabe et al., 2015; Yan et al., 2016
Appetite signaling, obesity	Hentzer and Givskov, 2003; Ley et al., 2006
Metabolic transformation of xenobiotics (small molecules foreign to the body)	Koppel et al., 2017