Across all 3 studies (all reviews), a small beneficial effect of Lactobacillus helveticus Rosell-52 on improved mental health was reported. No studies reported neutral or harmful findings, and none reported statistically significant results. The evidence base is small, and effect sizes were consistently small. No specific dose range, form, or study duration was reported, and populations were general adult humans.
Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. None of the included studies reported statistical significance — the observed beneficial effect may be smaller or less reliable than the direction suggests. All studies are reviews, not primary trials, which limits 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.