Probiotic Lactobacillus plantarum P8 alleviated stress and anxiety while enhancing memory and cognition in stressed adults: A randomised, double-blind, placebo-controlled study

Summary Background & aims To investigate the effects of probiotic in alleviation of stress in stressed adults, along our focus to identify and justify strain specificity on selected health benefits with a precisely targeted population. Methods This 12-weeks randomized, double-blind and placebo-controlled study investigated the effects of a probiotic ( Lactobacillus plantarum P8; 10 log CFU daily) on psychological, memory and cognition parameters in one hundred and three (P8 n = 52, placebo n = 51) stressed adults with mean age of 31.7 ± 11.1 years old. All subjects fulfilled the criteria of moderate stress upon diagnosis using the PSS-10 questionnaire. Results At the end of study, subjects on P8 showed reduced scores of stress (mean difference 2.94; 95% CI 0.08 to 5.73; P = 0.048), anxiety (mean difference 2.82; 95% CI 0.35 to 5.30; P = 0.031) and total score (mean difference 8.04; 95% CI 0.73 to 15.30; P = 0.041) as compared to placebo after 4-weeks, as assessed by the DASS-42 questionnaire. Although plasma cortisol levels were only marginally different between placebo and P8 (mean difference 3.28 ug/dl; 95% CI -7.09 to 0.52; P = 0.090), pro-inflammatory cytokines such as IFN-γ (mean difference 8.07 pg/ml; 95% CI -11.2 to −4.93; P  Conclusions The present data illustrated that L. plantarum P8 is a feasible and natural intervention for the alleviation of selected stress, anxiety, memory and cognitive symptoms in stressed adults. Trial registration Approved by the JEPeM-USM Review Panel on Clinical Studies (Approval number USM/JEPeM/16050195) and was registered at ClinicalTrials.gov (identifier number NCT03268447 ).