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.

Background: 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 Saccharomyces boulardii affects the level of salivary serotonin under psychological stress and identify the factors associated with it. Methods: Healthy medical students were randomized to ingest Saccharomyces boulardii 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. Results: Data of thirty-two participants (22.8 ± 1.7 years of age, 16 males) was available for the main analysis. Supplementation with Saccharomyces boulardii decreased salivary serotonin concentration under psychological stress by 3.13 (95% CI 0.20 to 6.07) ng/mL, p = 0.037, as compared to placebo. Salivary serotonin was positively correlated with salivary metanephrine (ß = 0.27, 95% CI 0.02 to 0.52, p = 0.031) and pulse rate (ß = 0.28, 95% CI 0.05 to 0.50, p = 0.018), but insignificantly with anxiety, depression, eating attitudes and information retrieval. Conclusions: Saccharomyces boulardii 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.

Effect of Supplementation with Saccharomyces Boulardii on Academic Examination Performance and Related Stress in Healthy Medical Students: A Randomized, Double-Blind, Placebo-Controlled Trial.

In recent years, bacterial probiotic dietary supplementation has emerged as a promising way to improve cognition and to alleviate stress and anxiety; however, yeast probiotics have not been tested. The aim of the present study was to determine whether 30-day supplementation with Saccharomyces boulardii enhances academic performance under stress and affects stress markers. The trial was retrospectively registered at clinicaltrials.gov (NCT03427515). Healthy medical students were randomized to supplement their diet with Saccharomyces boulardii CNCM I-1079 or placebo before sitting for an academic examination, which served as a model of stress. The grades of a final examination adjusted to subject knowledge tested in non-stressful conditions was used as a primary outcome measure. Psychometrically evaluated state anxiety, cortisol and metanephrine salivary levels, and pulse rate were tested at a non-stressful time point before the intervention as well as just before the stressor. Fifty enrolled participants (22.6 ± 1.4 years of age, 19 males) completed the trial in the Saccharomyces and placebo arms. Supplementation with Saccharomyces did not significantly modify examination performance or increase in state anxiety, salivary cortisol, and metanephrine. However, the intervention resulted in higher increase in pulse rate under stress as compared to placebo by 10.4 (95% CI 4.2-16.6) min-1 (p = 0.0018), and the effect positively correlated with increase in salivary metanephrine (Pearson's r = 0.35, 95% CI 0.09-0.58, p = 0.012). An intention-to-treat analysis was in line with the per-protocol one. In conclusion, supplementation with Saccharomyces boulardii CNCM I-1079 appears largely ineffective in improving academic performance under stress and in alleviating some stress markers, but it seems to increase pulse rate under stress, which may hypothetically reflect enhanced sympathoadrenal activity.

[Analysis of factors influencing neonatal bacterial flora of the conjunctiva shortly after delivery]. / Analiza czynników okoloporodowych wplywajacych na ksztaltowanie sie flory bakteryjnej worka spojówkowego noworodków.

OBJECTIVES: The aim of this study was the analysis of conjunctival flora in newborns within the first 72 hours of life, depending on the methods of delivery and other perinatal factors. MATERIAL AND METHODS: The study group consisted of 192 mothers and 192 newborns. Culture samples were obtained before delivery from the cervicovaginal secretions of pregnant women and, in case of caesarean sections, additionally from the maternal surface of the fetal membranes. Conjunctival specimens were obtained twice from the inferior conjunctival fornix of the right eye in all the newborns: early sample--immediately after the delivery and late sample--on the third day of neonatal life. Perinatal factors influencing bacterial colonization were analyzed. RESULTS: Statistically significant difference between the four clinical subgroups was found in the interval between the rupture of the membranes and delivery number of obstetrical examinations during delivery antibiotic use during the perinatal period and the presence of green amniotic fluid. Statistically significant difference was observed in the incidence of early sterile samples and method of delivery. The correlation between bacterial species obtained from conjunctival and cervicovaginal secretions samples was also found. The tendency for more frequent occurrence of early sterile samples was observed in newborns of mothers who received antibiotics in the perinatal period and if the interval between the rupture of the membranes and labor was shorter. CONCLUSIONS: The obtained data expanded the knowledge about neonatal conjunctival bacterial flora and demonstrated influence of the perinatal factors on bacterial colonization of the infants' conjunctiva.