AUTHOR=Karbownik Michał Seweryn , Kręczyńska Joanna , Wiktorowska-Owczarek Anna , Kwarta Paulina , Cybula Magdalena , Stilinović Nebojša , Pietras Tadeusz , Kowalczyk Edward 

TITLE=Decrease in Salivary Serotonin in Response to Probiotic Supplementation With Saccharomyces boulardii in Healthy Volunteers Under Psychological Stress: Secondary Analysis of a Randomized, Double-Blind, Placebo-Controlled Trial

JOURNAL=Frontiers in Endocrinology

VOLUME=12

YEAR=2022

URL=https://www.frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2021.800023

DOI=10.3389/fendo.2021.800023

ISSN=1664-2392

ABSTRACT=<sec><title>Background</title><p>Bacterial probiotics are thought to exert a serotonergic effect relevant to their potential antidepressant and pro-cognitive action, but yeast probiotics have not been tested. The aim of the present study was to determine whether 30-day supplementation with <italic>Saccharomyces boulardii</italic> affects the level of salivary serotonin under psychological stress and identify the factors associated with it.</p></sec><sec><title>Methods</title><p>Healthy medical students were randomized to ingest <italic>Saccharomyces boulardii</italic> CNCM I-1079 or placebo before a stressful event. Salivary serotonin concentration was assessed before and at the end of supplementation. Moreover, obtained results were compared to psychological, biochemical, physiological and sociodemographic study participants data.</p></sec><sec><title>Results</title><p>Data of thirty-two participants (22.8 ± 1.7 years of age, 16 males) was available for the main analysis. Supplementation with <italic>Saccharomyces boulardii</italic> decreased salivary serotonin concentration under psychological stress by 3.13 (95% CI 0.20 to 6.07) ng/mL, <italic>p</italic> = 0.037, as compared to placebo. Salivary serotonin was positively correlated with salivary metanephrine (β = 0.27, 95% CI 0.02 to 0.52, <italic>p</italic> = 0.031) and pulse rate (β = 0.28, 95% CI 0.05 to 0.50, <italic>p</italic> = 0.018), but insignificantly with anxiety, depression, eating attitudes and information retrieval.</p></sec><sec><title>Conclusions</title><p><italic>Saccharomyces boulardii</italic> CNCM I-1079 may be distinct from bacterial probiotics in its salivary serotonergic effect, which appears positively linked to symapathoadrenal markers. The study requires cautious interpretation, and further investigation.</p></sec>