Across 3 review-level studies (no original RCTs), all reported small beneficial effects of Lactobacillus helveticus Rosell-52 on mental health outcomes in adult humans. No statistically significant findings were documented in the database, and no specific dose, form, or duration data were extracted. Effects were consistently small in magnitude.
Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. Available evidence is overwhelmingly positive — clinical literature in this area is subject to publication bias (null-result studies are less likely to be published or indexed). Many of the included studies did not reach statistical significance — effect may be smaller than the predominant direction suggests. All three studies are reviews, not original trials, limiting the strength of causal inference.
it appears that probiotics have a beneficial effect on mental health, cognitive functions, sleep, gastrointestinal, and upper respiratory symptoms in adult humans.
Ten studies investigated the same combination of probiotics and provided evidence to support the claims made. Statistically significant results were not universally present for all products.
The highest therapeutic potential is seen in the rational diet, physical activity, use of psychobiotics, and consumption of antioxidants. Research also shows that there are nutritional interventions that have psychoprotective potential.