Benefits
Overall distress and mood subscale scores in healthy adults
In a 30-day double-blind, placebo-controlled trial in 55 healthy volunteers, 3 billion CFU a day improved an overall distress index and its somatization, depression and anger-hostility subscales more than placebo, plus the HADS total score. The anxiety subscale the trial was sized on, the HADS anxiety (P = 0.06) and depression subscales, perceived stress and urinary cortisol did not differ between groups. The maker funded it.
Self-rated mood over 12 weeks in working adults with poor sleep
In a 12-week placebo-controlled trial of Cerebiome® in 70 adults with mild to moderate insomnia symptoms tied to work stress, the primary outcome, insomnia severity, fell equally in both groups. On a secondary outcome, self-rated depressive symptom scores (PHQ-9) improved more with the probiotic (p = 0.05). Lallemand supplied the product and helped design and run the trial; four authors work for Lallemand.
Self-rated mood scores alongside SSRI medicines over 8 weeks
In 110 adults with major depression who all stayed on SSRI medicines, 10 billion CFU a day for 8 weeks lowered Beck Depression Inventory scores from 17.4 to 9.1, against 18.2 to 15.6 with placebo (81 completed). Because the pair was added to prescribed drugs in a diagnosed group, this cannot show what it does alone. A later analysis reported higher BDNF. Lallemand supplied the product.
Mood scores in two placebo-controlled trials
Two double-blind trials of 3 billion CFU a day found no whole-group benefit over placebo: one in 79 adults with low mood who took no psychiatric medicines (8 weeks; Lallemand funded the products and blood tests) and one in 116 adults with depression, some on antidepressants (60 days; p = 0.45). In the larger trial, more people on the probiotic reached a minimum meaningful improvement (74.5% versus 53.5%).
Anxiety and wellbeing in healthy adults
In a 4-week placebo-controlled trial in 135 healthy adults, 3 billion CFU a day of Cerebiome® had no significant effect on wellbeing, quality of life, emotional regulation, anxiety, mindfulness or body awareness in the whole group. In a secondary model, probiotic intake combined with healthier lifestyle habits predicted better anxiety, emotional regulation and mindfulness scores. Rosell-Lallemand supplied the products.
Abdominal pain and nausea scores in volunteers
In a 3-week double-blind, placebo-controlled trial of Probio'Stick® (3 billion CFU a day) in volunteers reporting stress symptoms, abdominal pain and nausea or vomiting scores were reduced, while other physical and psychological symptoms and sleep problems did not change significantly. The abstract does not give the number of participants. A small 12-week trial in female dancers found no change in gut symptoms.
Mechanism of action
Anxiety-like behavior in rats (animal work only)
In the 2011 paper that also reported the human trial, rats given the pair for 2 weeks showed less anxiety-like behavior in a conditioned defensive burying test. This is an animal result and does not show the same effect in people.
HPA axis and urinary cortisol
In the 30-day trial in healthy volunteers, 24-hour urinary free cortisol fell within the probiotic group but did not differ from placebo between groups, so an effect on the body's stress-hormone system was not shown.
Vagal afferent signaling
Communication from the gut to the brain along the vagus nerve is one proposed route for probiotic effects on mood. No study cited on this page tested this for these two strains, so treat it as a theory rather than a demonstrated effect.
Short-chain fatty acid production
Gut bacteria can produce short-chain fatty acids that act on the gut lining and on nerve signaling. This is general probiotic theory and was not shown for this pair in the trials cited on this page.
Tryptophan / serotonin precursor modulation
Changes in how the gut handles tryptophan could in theory affect the supply of the building blocks of serotonin. In the 8-week trial in adults taking SSRIs, the kynurenine to tryptophan ratio did not differ between groups in the main comparison and was lower with the probiotic only after adjusting for the amino acid isoleucine.
Gut barrier integrity and reduced systemic inflammation
Probiotics are proposed to help keep the gut lining intact and limit inflammatory molecules passing into the blood. In the low-mood trial, inflammatory blood markers did not change compared with placebo.
Synergistic two-strain combination
The human trials tested the two strains together, so their results cannot be credited to either strain on its own. No study cited here compared the combination against the single strains, so a synergy claim is not supported.
BDNF, a brain growth factor
In a post hoc analysis of the 8-week trial in adults taking SSRIs, blood levels of BDNF rose with the probiotic compared with placebo and the prebiotic, and higher BDNF tracked with lower depression scores. This is an exploratory analysis of one trial.
Clinical trials
Randomized, double-blind, placebo-controlled parallel trial; one 3 billion CFU Probio'Stick® sachet a day for 30 days; funded by Rosell-Lallemand; the paper also reports a separate rat experiment (Messaoudi et al. 2011, Br J Nutr)
55 healthy adult volunteers completed (26 probiotic, 29 placebo); people who had taken psychotropic drugs in the previous month were excluded
Change in the HSCL-90 global severity index and its somatization, depression and anger-hostility subscales favored the probiotic over placebo (P < 0.05), as did the HADS total score (P = 0.03). The HSCL-90 anxiety subscale, on which the sample size was calculated, did not differ, nor did the HADS anxiety (P = 0.06) or HADS depression (P = 1) subscales. Perceived Stress Scale scores and 24-hour urinary free cortisol did not differ between groups; cortisol fell within the probiotic group only.
Randomized, double-blind, placebo-controlled parallel trial (NCT04767997) of Cerebiome® daily for 12 weeks in adults with insomnia symptoms tied to work-related stress; the PHQ-9 is not among the outcomes listed in the trial registration, and the abstract gives no between-group result for registered secondary outcomes such as work-related stress and psychological distress; Lallemand provided the products and collaborated in design, conduct, analysis and reporting, and four authors are Lallemand employees (Binda et al. 2026, Sleep Med)
70 adults aged 18 to 65 with mild to moderate insomnia symptoms and no diagnosed mental disorder (35 probiotic, 35 placebo)
The primary outcome, the Insomnia Severity Index, fell in both groups with no between-group difference (p = 0.82). On a secondary outcome, PHQ-9 depressive symptom scores improved more with the probiotic than placebo (p = 0.05, d = 0.51). Adverse events did not differ and none were severe.
Randomized, double-blind, placebo-controlled trial in adults with major depressive disorder who were taking SSRIs; one 10 billion CFU sachet a day, a galactooligosaccharide prebiotic or placebo; the primary outcome was the Beck Depression Inventory; Lallemand supplied the products; a drug co-treatment result in a diagnosed population (Kazemi et al. 2019, Clin Nutr)
110 adults with a clinical diagnosis, all on prescribed SSRI medicines; 81 completed
The primary self-rated symptom score fell from 17.39 to 9.1 with the probiotic versus 18.18 to 15.55 with placebo and 19.72 to 14.14 with the prebiotic (p = 0.042). The kynurenine to tryptophan ratio did not differ between groups unless adjusted for isoleucine.
Randomized, double-blind, placebo-controlled trial in adults selected for low mood; one 3 billion CFU sachet a day; Lallemand provided the products and paid for blood testing, and the lead author has received research funding from Lallemand (Romijn et al. 2017, Aust N Z J Psychiatry)
79 adults with at least moderate scores on self-report questionnaires, not taking psychiatric medicines; 10 dropped out
No difference from placebo on any psychological measure (effect sizes 0.07 to 0.16) or blood marker. Responders: 9 (23%) on the probiotic and 10 (26%) on placebo. Dry mouth and sleep disruption were reported more often on placebo.
Randomized, double-blind, placebo-controlled parallel trial (PRO-DEMET) in adults with depression, some taking antidepressants; one 3 billion CFU capsule a day of Sanprobi Stress made with Rosell-Lallemand probiotic powder; funded by the Medical University of Lodz (Gawlik-Kotelnicka et al. 2024, Nutrients)
116 adult outpatients with a diagnosed disorder, some on prescribed medicines; 94 analyzed for the responder comparison
No overall difference from placebo on the main symptom score (p = 0.45). More people on the probiotic reached a minimum clinically important improvement (74.5% versus 53.5%, p = 0.03). Greater metabolic problems at the start, such as excess belly fat, went with smaller improvements. No serious adverse events.
Randomized, placebo-controlled trial (NCT04823533); 3 billion CFU of Cerebiome® a day for 4 weeks; outcomes were wellbeing, quality of life, emotional regulation, anxiety, mindfulness and interoceptive awareness; in a secondary model, probiotic intake combined with high healthy-behavior scores predicted better anxiety, emotional regulation and mindfulness scores; Rosell-Lallemand supplied the products and the authors report no financial ties to it (Morales-Torres et al. 2023, Nutrients)
135 healthy adults
No significant effect of the probiotic on any of the six questionnaire outcomes in the whole sample.
Randomized, double-blind, placebo-controlled trial in volunteers with symptoms of stress; one Probio'Stick® sachet a day (3 billion CFU of L. helveticus Rosell-52, then named L. acidophilus, and B. longum Rosell-175) or placebo; product from Lallemand (Diop et al. 2008, Nutr Res)
Adult volunteers with self-reported symptoms; the abstract does not give the number of participants
Abdominal pain and nausea or vomiting scores were reduced with the probiotic in both intention-to-treat and per-protocol analyses. Other physical and psychological symptoms and sleep problems did not change significantly.
Randomized, placebo-controlled trial (NCT05567653); 3 billion CFU a day in Sanprobi Stress capsules made with Lallemand probiotic powder for 12 weeks; four authors are shareholders, employees or paid by a probiotic company; a companion paper from the same trial found no between-group differences in blood endocannabinoid or inflammatory markers or coping scores (Wiącek et al. 2025, Int J Mol Sci)
26 female dancers randomized; 16 analyzed (5 probiotic, 11 placebo)
No improvement in gastrointestinal symptoms on the Rome IV questionnaire. The stool metabolite profile shifted in the probiotic group. No adverse events.