Table 3.

Preclinical and clinical evidence for the effect of probiotics in treating depression.

Refs.	Species Used	Tests Performed	Probiotics Used	Result/Outcome
Y.-W. et al., 2016 [91]	ELS mice, Naïve mice	Sucrose- preference test, forced-swim test	L.plantarum PS128 for 28 days	Decreased depression in ELS mice, increased 5-HT and Dopamine.
Liang et al., 2015 [92]	SPF CRS rats	Sucrose- preference test	L.helvectivus NS8 for 21 days	Decreased depression, increase in 5-HT and NA levels.
Savignac et al., 2015 [93]	mice	Tail-suspension test, forced- swim test	B.longum 1714/ B.breve 1205 for 21 days	Decreased depression in mice.
Bravo et al., 2011 [94]	mice	Forced-swim test	L.rhamnosus JB-1 for 28 days	Decreased depression, probiotic effect via vagal neurons.
Steenbergen et al., 2015 [95]	40 Human volunteers	Leiden index of the depression sensitivity scale	B.bifidum W23, B.lactis W52, L.acidophilus W37, L.brevis W63, L.casei W56, L.salivarius W24 and Lactococcus lactis (W19 and W58) for 4 weeks	Reduced overall cognitive reactivity to sad mood
Pinto-Sanchez et al., 2017 [96]	44 Human volunteers	Hospital Anxiety and Depression scale, Functional MRI	B.longum NCC3001 for 6 weeks	Reduced depression and reduced response to negative stimuli in multiple regions of brain-like amygdala and fronto-limbic regions
Slykerman et al., 2017 [97]	423 female human volunteers who are either pregnant or in postpartum period	Edinburgh postnatal depression scale	L.rhamnosus HN001 was given from 14-16weeks of gestation to 6 months postpartum	Reduced depression scores in women postpartum