Stress relief benefits of gut microbiome may not extend to fungal components

The human gut microbiome is a diverse assemblage of hundreds of bacterial species as well as fungal and viral components.  Most of the research into how the functional aspects of the gut can be altered by supplementation has focused on bacterial ingredients.  Yeasts have been studied as well, mostly in conjunction with alleviating diarrhea.

Stress relief effects of probiotics

Recent research into bacterial probiotic species has looked into the possibility of helping consumers cope with stress via probiotic supplementation.  A study published slightly more than a year ago using Lactobacillus plantarum DR7​ found that it may up regulate serotonin pathways and stabilize dopamine pathways in the brains of stressed adults​​.

Now researchers are starting to ask whether fungal ingredients commonly used in supplements could confer a similar benefit. A recent study published in the journal Nutrients ​looked into whether a particular Saccharomyces boulardii​ yeast (CNCM I-1079) could improve academic performance against placebo for medical students sitting for a test, which served as a stress model.  The research  was performed by academics associated with a university in Poland and an institute in Oklahoma City, OK in the United States.

Medical school test used as stressor

The test involved Polish medical school students sitting for a pharmacology test at a school in Lodz.  The original test design involved three arms of about 30 students each:  a yeast group, who consumed a Saccharomyces boulardii​ CNCM I-1079 product manufactured by Canadian firm Institut Rosell, a placebo group and a probiotic arm.  The products were loaded into identical capsules purchased from an Indian supplier to disguise their identities.  The students took the yeast or placebo capsules for 30 days prior to the test. The probiotic arm was eliminated from the study when the probiotic used was found to have degraded.

In addition to performance on the test (which was measured against a pre test the day before), students took their pulse rates and gathered saliva samples which were analyzed for stress biomarkers.

Main endpoint inconclusive

The researchers found that while the yeast group performed slightly better on the test than did the placebo group, the difference did not clear the statistical significance bar.  However, the yeast supplementation did seem to raise the students’ pulse rates against those of their peers, which the researchers said could open the door to an interesting side result, with a major caveat that the self-reported nature of the pulse rate increase was a significant drawback to drawing any firm conclusions from this subsidiary finding.

“The supplementation has significant effect on neither performance in academic examination nor state anxiety, salivary cortisol, and metanephrine. However, the supplementation appears to increase pulse rate under stress, which may hypothetically reflect enhanced sympathoadrenal activity. The results of pulse rate increase should be regarded with caution due to limited validity of the measure. The findings require confirmation and exploration at clinical, preclinical, and in vitro levels, applying more accurate methods. The study has the potential to drive research forward particularly in the neglected field of pro-cognitive and antianxiety properties of fungal probiotics,” ​the authors concluded.

Source:​ Nutrients​​​
2020, 12​(5), 1469; https://doi.org/10.3390/nu12051469
Effect of Supplementation with​ Saccharomyces Boulardii on Academic Examination Performance and Related Stress in Healthy Medical Students: A Randomized, Double-Blind, Placebo-Controlled Trial​
Authors: Karbownik SW et al.