Table 2.

Overview of clinical evidence supporting the psychobiotic properties of some bacterial strains.

Form, Bacterial Strain	Dose	Effects
Postbiotic, Bacillus coagulans MTCC 5856	2 trillion spores	Effective in treating patients with IBS symptoms who had been diagnosed with depression [165].
Probiotic, Bifidobacterium longum 1714	1 × 109 CFU/d	Reduced stress symptoms and improved memory [166].
Probiotic, Bifidobacterium longum NCC3001	1 × 1010 CFU/g	Reduced symptoms of depression and reduced reactions to negative emotional stimuli [167].
Probiotic, Clostridium butyricum MIYAIRI 588	60 mg/d	When combined with antidepressants, this strain was effective in treating drug-resistant depression [168].
Probiotic, Lactobacillus casei Shirota	1 × 109 for 8 weeks	Reduced perceived stress [169].
Probiotic, Lactobacillus gasseri CP2305	1 × 1010 CFU	Reduced reactions to stressful situations and improved sleep quality [170].
Multi-strain probiotic supplement, Bifidobacterium bifidum W23, Bifidobacterium lactis W52, Lactobacillus acidophilus W37, Lactobacillus brevis W63, Lactobacillus casei W56, Lactobacillus salivarius W24, Lactococcus lactis (W19 and W58)	2.5 × 109 CFU/g	Reduced susceptibility to lowered mood states [171].
Multi-strain probiotic supplement, Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium bifidum, Lactobacillus fermentum	1 capsule contained 2 × 109 CFU/g per day, administered for 12 weeks	Improved overall health; reduced anxiety symptoms and depressive conditions. Reduction in inflammation in the body [172].
A fermented beverage made from black soybeans, Lactobacillus gasseri CP2305	190 g serving once a day for 5 weeks	Improved sleep quality and reduced stress-related symptoms in healthy adults [170].
A fermented beverage made from black soybeans, Lactobacillus casei Shirota	100 mL serving once a day for 8 weeks	Increased serotonin levels in the body. Reduced stress symptoms in people exposed to stressful situations [173].
Probiotic milk drink, Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium bifidum, Lactobacillus fermentum	200 mL serving once a day for 12 weeks	Positive effects on cognitive function in patients with Alzheimer’s disease (aged 60–95 years) [174].
Fermented soybean seed paste, Lactobacillus plantarum C29	800 mg per day for 12 weeks	Improved cognitive function in people with mild cognitive impairment [175].
Unpasteurized milk and dairy products, Lactobacilli	Unlimited consumption for 12 weeks	Reduced stress reactions and anxiety in adults [176].
Probiotic yogurt, Lactobacillus acidophilus LA5 and Bifidobacterium lactis BB12	100 g serving once a day for 6 weeks	Positive impact on depression treatment; improvement in symptoms of depression, anxiety, and stress among adults [177].
Yogurt, Lactobacillus gasseri SBT2055 and Bifidobacterium longum SBT2928	100 g once a day for 12 weeks	Decreased levels of stress-induced hormone adrenocorticotrophic hormone [178].