Keywords: well-beingphysiologyneurotransmittershormonesinflammatory markersmicrobiome 4. Discussion Future directions for a complete picture of the physiological factors underlying well-being are proposed. The inconsistent and limited results for other markers and microbiome require further research. The results indicate possible but small roles of serotonin, cortisol, and inflammatory markers in explaining differences in well-being. Microbiome studies (k=4) reported inconsistent associations between different bacteria abundance and well-being. Inflammatory marker studies (k=36) reported negative or non-significant relations with well-being, with meta-analytic estimates of respectively r=-.07 and r=-.05 for C-reactive protein and interleukin-6. For the hormone studies (k=48), a lower momentary cortisol level was related to higher well-being (meta-analytic r=-.06), and a steeper diurnal slope of cortisol levels. Neurotransmitter studies (knumber of studies=9) reported only a possible positive association between serotonin and well-being. To understand the pathways through which well-being contributes to health, we performed a systematic review according to the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines on the association between well-being and physiological markers in four categories, neurotransmitters, hormones, inflammatory markers, and microbiome.
More research to the physiological factors underlying well-being is needed.An association between the microbiome composition and well-being is suggested.The levels of different inflammatory markers are negatively related to well-being.Faster decrease of cortisol levels over the day is associated with higher well-being.Higher blood levels of serotonin could be related to higher well-being.Neuroscience & Biobehavioral Reviews, June 11 2022, 104733. The human physiology of well-being: A systematic review on the association between neurotransmitters, hormones, inflammatory markers, the microbiome and well-being.