Influence of a Commercially Available Probiotic Pill on Gut Microbiome and Stress Response in Healthy Human Subjects - Abstract
Animal studies have shown that dietary probiotics can modify host stress response viathe gut-brain axis. A few studies with healthy human subjects have indicated that single strain fermented milk probiotic products can alter stress response. The aim of this study was to investigate whether consumption of commercially available multispecies probiotic pills could affect the gut microbiome and stress response in healthy humans. A treated group (ingested probiotic pills) and a control group (no probiotic pills) were subjected to an elevated height ropes course (EHRC) as stressor. Stress response was measured using ELISA of salivary cortisol. Fecal bacteria DNA was sequenced by Illumina. Questionnaires assessed perceived stress and gut health. Although bacterial community structure and diversity showed no changes over time, treated subjects had significantly increased abundance of Lactobacilli and Bifidobacteria compared to controls on day 15. These two different trends would not be observed in studies that use one or the other set of markers (species specific vs. general primers). Stress response to the EHRC showed no significant differences between treated and control groups, yet cortisol values in the treated group were slightly dampened relative to controls on day 15. Overall, this study indicated that probiotic pill had a slight but significant effect on probiotic bacteria abundance, but not gut bacteria community structure, stress, or gut health. We speculate that live yogurt cultures may be needed to substantially impact both gut community structure and stress response.