• 1 1 School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang, Malaysia
  • 2 2 School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Malaysia
  • 3 3 School of Data Sciences, Perdana University, 43400 Serdang, Malaysia
  • 4 4 Community Health Center, Universiti Sains Malaysia, 11800 Penang, Malaysia
  • 5 5 Advanced Medical and Dental Institute, Universiti Sains Malaysia, 13200 Bertam, Malaysia
  • 6 6 Clinical Nutrition Intl (M) Sdn Bhd, 43200 Selangor, Malaysia
  • 7 7 Department of Biotechnology, Yeungnam University, Joyeong-dong, Gyeongsan, Gyeongsangbuk-do, 712-749, South Korea
Benef Microbes, 2019 Apr 19;10(4):355-373.
PMID: 30882244 DOI: 10.3920/BM2018.0135


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.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.