| 30-day double-blind, placebo controlled RCT |
55 healthy adults, aged 30–60 years |
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Participants in probiotic (L. helveticus R0052, B. longum R0175) group had significantly reduced HSCL-90 scores (global severity index, z = 1.98; somatization z = 2.16; depression z = 1.96; and anger-hostility z = 2.41), and HADS-global (z = 2.19) and HADS-anxiety (z = 1.92) scores, between time-points compared to placebo group.
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Participants in probiotic group had significant decrease in median urinary free cortisol (UFC) level between time-points; no significant change in UFC among controls.
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| Once daily probiotic (one stick 1.5g combination of L. helveticus R0052 and B. longum R0175, 3 × 109 CFU/stick) |
Probiotic group: 42.4 ± 7.5 yo |
| Messaoudi et al. (2011) |
Placebo group: 43.2 ± 8.5 yo |
| 8-week repeated measures, placebo-controlled design. Placebo for 4 weeks, followed by probiotic (1 × 109 CFU stick of Bifidobacterium longum 1714) for 4 weeks. |
22 healthy adults, aged 18–40 |
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At the post-probiotic (B. Longum 1714) visit, significantly lower cortisol increase in response to cold-stressor test (compared to placebo, r = 0.42; and compared to baseline, r = 0.45).
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State anxiety was significantly elevated in response to cold stressor test post-placebo (r = 0.57), but not post-probiotic (r = 0.12).
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Subjective stress, as measured with AUCg, was significantly lower during the 1714 condition compared with the placebo (Cohen's d = 0.53).
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Frontal midline electroencephalographic mobility was significantly higher post-probiotic compared with post-placebo (r = 0.31).
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| Allen et al. (2016) |
Mean age: 25.5 ± 1.2 yo |
| 6-week double-blind, placebo controlled RCT |
44 adults with IBS and mild to moderate anxiety and/or depression (HAD-A or HAD-D score 8–14) |
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14 out of 22 (64%) participants in the B. longum NC 3001 group had decreased HAD-D scores (≥2 points), compared with 7 out of 22 (32%) participants in the placebo group.
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Significant reduction in HAD-D scores between time-points in BL group compared to placebo group (when accounting for baseline differences).
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After treatment, participants in BL group (compared with placebo group) showed: 1)reduced engagement of the amygdala, frontal and temporal cortices, as well as 2)heightened engagement of occipital regions, in response to the fear stimuli (relative to fixation).
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Within the BL group, reduced engagement of the amygdala correlated with decreased depression scores (r = 0.58, p = .03) – pattern not observed among placebo group.
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| Once daily probiotic (B. longum NCC 3001, 1 × 1010 CFU/1g powder) or placebo for 6 weeks. |
Probiotic group median age: 46.5 (30–58)yo |
| Pinto et al. (2017) |
Placebo group median age: 40.0 (26–57) yo |
