Bifidobacterium bifidum R0071 decreases stress-associated diarrhoea-related symptoms and self-reported stress: a secondary analysis of a randomised trial.

Psychological stress is associated with gastrointestinal (GI) distress. This secondary analysis from a randomised, double-blind, placebo-controlled study examined whether three different probiotics could normalise self-reported stress-associated GI discomfort and reduce overall self-reported stress. Undergraduate students (n=581) received Lactobacillus helveticus R0052, Bifidobacterium longum ssp. infantis R0033, Bifidobacterium bifidum R0071, or placebo. Participants self-reported 2 outcomes for a 6-week period, which included final academic exams: daily level of stress (0=no stress to 10=extremely stressed) and weekly three diarrhoea-related symptoms (DS, 1=no discomfort to 7=severe discomfort) using the GI Symptom Rating Scale. Self-reported stress was positively related to DS (P=0.0068). Mean DS scores were lower with B. bifidum versus placebo at week 2 at the average level of stress and the average body mass index (BMI). DS scores were lower with B. bifidum at week 5 versus week 0 and 1 and with B. infantis R0033 at week 6 versus week 0. DS scores were higher when antibiotics were used in the prior week with placebo (P=0.0092). DS were not different with or without antibiotic use with the probiotics. Only B. bifidum had an effect on self-reported stress scores (P=0.0086). The self-reported stress score was also dependent on hours of sleep per day where it decreased by 0.13 for each additional hour of sleep. During a stressful period, B. bifidum R0071 decreases DS and self-reported stress scores. This trial was registered at clinicaltrials.gov as NCT01709825.