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

• Main Authors: Michał Seweryn Karbownik, Joanna Kręczyńska, Paulina Kwarta, Magdalena Cybula, Anna Wiktorowska-Owczarek, Edward Kowalczyk, Tadeusz Pietras, Janusz Szemraj
• Format: Article
• Language: English
• Published: MDPI AG 2020-05-01
• Series: Nutrients
• Subjects: <i>Saccharomyces boulardii</i>; dietary supplementation; probiotic; academic examination; stress; anxiety
• Online Access: https://www.mdpi.com/2072-6643/12/5/1469

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 <i>Saccharomyces boulardii</i> 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 <i>Saccharomyces boulardii</i> 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 <i>Saccharomyces</i> and placebo arms. Supplementation with <i>Saccharomyces</i> 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 (<i>p</i> = 0.0018), and the effect positively correlated with increase in salivary metanephrine (Pearson’s r = 0.35, 95% CI 0.09–0.58, <i>p</i> = 0.012). An <i>intention-to-treat</i> analysis was in line with the <i>per-protocol</i> one. In conclusion, supplementation with <i>Saccharomyces boulardii</i> 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.