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Fermented milk containing Lactobacillus casei strain Shirota prevents the onset of physical symptoms in medical students under academic examination stress.

  • 2016-03-11
  • Beneficial Microbes 7(2)
    • Akito Kato-Kataoka
    • K. Nishida
    • M. Takada
    • K. Suda
    • M. Kawai
    • K. Shimizu
    • Akira Kushiro
    • R. Hoshi
    • O. Watanabe
    • Tomoki Igarashi
    • K. Miyazaki
    • Y. Kuwano
    • K. Rokutan

Abstract

This pilot study investigated the effects of the probiotic Lactobacillus casei strain Shirota (LcS) on psychological, physiological, and physical stress responses in medical students undertaking an authorised nationwide examination for promotion. In a double-blind, placebo-controlled trial, 24 and 23 healthy medical students consumed a fermented milk containing LcS and a placebo milk, respectively, once a day for 8 weeks until the day before the examination. Psychophysical state, salivary cortisol, faecal serotonin, and plasma L-tryptophan were analysed on 5 different sampling days (8 weeks before, 2 weeks before, 1 day before, immediately after, and 2 weeks after the examination). Physical symptoms were also recorded in a diary by subjects during the intervention period for 8 weeks. In association with a significant elevation of anxiety at 1 day before the examination, salivary cortisol and plasma L-tryptophan levels were significantly increased in only the placebo group (P<0.05). Two weeks after the examination, the LcS group had significantly higher faecal serotonin levels (P<0.05) than the placebo group. Moreover, the rate of subjects experiencing common abdominal and cold symptoms and total number of days experiencing these physical symptoms per subject were significantly lower in the LcS group than in the placebo group during the pre-examination period at 5-6 weeks (each P<0.05) and 7-8 weeks (each P<0.01) during the intervention period. Our results suggest that the daily consumption of fermented milk containing LcS may exert beneficial effects preventing the onset of physical symptoms in healthy subjects exposed to stressful situations.

Keywords: physical symptoms; probiotics; salivary cortisol; serotonin; tryptophan.

Research Insights

SupplementHealth OutcomeEffect TypeEffect Size
Lacticaseibacillus caseiIncreased Serotonin LevelsBeneficial
Moderate
Lacticaseibacillus caseiReduced Anxiety LevelsBeneficial
Moderate
Lacticaseibacillus caseiStabilized Cortisol LevelsBeneficial
Moderate
Lacticaseibacillus casei R0215Increased Serotonin LevelsBeneficial
Moderate
Lacticaseibacillus casei R0215Reduced Anxiety ResponsesBeneficial
Moderate
Lacticaseibacillus casei R0215Reduced Physical SymptomsBeneficial
Large
Lactobacillus caseiIncreased Faecal Serotonin LevelsBeneficial
Moderate
Lactobacillus caseiReduced Salivary Cortisol Levels Under StressBeneficial
Moderate
Lactobacillus casei HA-108Increased Faecal Serotonin LevelsBeneficial
Moderate
Lactobacillus casei HA-108Reduced Anxiety LevelsBeneficial
Moderate
Lactobacillus casei LC03Increased Faecal Serotonin LevelsBeneficial
Moderate
Lactobacillus casei LC03Reduced Physical Symptoms of StressBeneficial
Large
Lactobacillus casei LC03Stabilized Physiological Stress MarkersBeneficial
Moderate
Lactobacillus casei Lc-11Increased Faecal Serotonin LevelsBeneficial
Moderate
Lactobacillus casei Lc-11Reduced Anxiety LevelsBeneficial
Moderate
Lactobacillus casei Lc-11Reduced Physical SymptomsBeneficial
Large
Lactobacillus casei PXN 37Increased Faecal Serotonin LevelsBeneficial
Moderate
Lactobacillus casei PXN 37Reduced Anxiety LevelsBeneficial
Moderate
Lactobacillus casei R0215Increased Faecal Serotonin LevelsBeneficial
Moderate
Lactobacillus casei SD5213Reduced Anxiety-Related Physiological ChangesBeneficial
Moderate
Lactobacillus casei SD5213Reduced Pre-Examination Physical SymptomsBeneficial
Moderate
Lactobacillus casei SD-5213Increased Faecal Serotonin LevelsBeneficial
Moderate
Lactobacillus casei SD-5213Reduced Salivary Cortisol Levels Under StressBeneficial
Moderate
Lactobacillus casei SD-5842Elevated Fecal Serotonin LevelsBeneficial
Small
Lactobacillus casei SD-5842Reduced Anxiety BiomarkersBeneficial
Moderate
Lactobacillus casei SD-5842Reduced Physical SymptomsBeneficial
Large
Lactobacillus casei subsp. caseiIncreased Faecal Serotonin LevelsBeneficial
Moderate
Lactobacillus casei subsp. caseiReduced Physical Symptoms of StressBeneficial
Large
Lactobacillus casei subsp. caseiReduced Salivary Cortisol Levels Under StressBeneficial
Moderate
Lactobacillus casei UALc-03Increased Faecal Serotonin LevelsBeneficial
Moderate
Lactobacillus casei UALc-03Reduced Anxiety-Related BiomarkersBeneficial
Moderate
Lactobacillus casei UALc-03Reduced Physical Symptoms of StressBeneficial
Large
Lactobacillus casei VK4Reduced AnxietyBeneficial
Large
Lactobacillus casei VK4Reduced Physical Symptoms of StressBeneficial
Large
Lactobacillus fermentum MAK20L13FIncreased Faecal Serotonin LevelsBeneficial
Moderate
Lactobacillus fermentum MAK20L13FReduced AnxietyBeneficial
Large
Lactobacillus fermentum MAK20L13FReduced Physical SymptomsBeneficial
Large
Lactobacillus genseniIncreased Faecal Serotonin LevelsBeneficial
Moderate
Lactobacillus genseniReduced Salivary Cortisol Levels Under StressBeneficial
Moderate

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