Lactobacillus plantarum DR7 alleviates stress and anxiety in adults: a randomised, double-blind, placebo-controlled study

Benef Microbes. 2019 Apr 19;10(4):355-373. doi: 10.3920/BM2018.0135. Epub 2019 Mar 18.


Probiotics have been reported to exert beneficial effects along the gut-brain axis. This randomised, double-blind and placebo-controlled human study aimed to evaluate such properties of Lactobacillus plantarum DR7 and its accompanying mechanisms in stressed adults. One hundred and eleven (n=111; DR7 n=56, placebo n=55) stressed adults were recruited based on moderate stress levels using the PSS-10 questionnaire. The consumption of DR7 (1×109 cfu/day) for 12 weeks reduced symptoms of stress (P=0.024), anxiety (P=0.001), and total psychological scores (P=0.022) as early as 8 weeks among stressed adults compared to the placebo group as assessed by the DASS-42 questionnaire. Plasma cortisol level was reduced among DR7 subjects as compared to the placebo, accompanied by reduced plasma pro-inflammatory cytokines, such as interferon-γ and transforming growth factor-α and increased plasma anti-inflammatory cytokines, such as interleukin 10 (P<0.05). DR7 better improved cognitive and memory functions in normal adults (>30 years old), such as basic attention, emotional cognition, and associate learning (P<0.05), as compared to the placebo and young adults (<30 years old). The administration of DR7 enhanced the serotonin pathway, as observed by lowered expressions of plasma dopamine β-hydroxylase (DBH), tyrosine hydroxylase (TH), indoleamine 2,3-dioxygenase and tryptophan 2,3-dioxygenase accompanied by increased expressions of tryptophan hydroxylase-2 and 5-hydroxytryptamine receptor-6, while stabilising the dopamine pathway as observed via stabilised expressions of TH and DBH over 12 weeks as compared to the placebo (P<0.05). Our results indicated that DR7 fulfil the requirement of a probiotic strain as per recommendation of FAO/WHO and could be applicable as a natural strategy to improve psychological functions, cognitive health and memory in stressed adults.

Keywords: DR7; anxiety; cognition; memory; serotonin; stress.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Anxiety / microbiology
  • Anxiety / prevention & control*
  • Anxiety / psychology
  • Cognition / physiology
  • Cytokines / blood
  • Double-Blind Method
  • Humans
  • Hydrocortisone / blood
  • Lactobacillus plantarum / physiology*
  • Memory / physiology
  • Middle Aged
  • Neurotransmitter Agents / blood
  • Probiotics / administration & dosage*
  • Serotonin / blood
  • Stress, Psychological / microbiology
  • Stress, Psychological / psychology
  • Stress, Psychological / therapy*
  • Treatment Outcome
  • Young Adult


  • Cytokines
  • Neurotransmitter Agents
  • Serotonin
  • Hydrocortisone