Writing in Food and Function, the researchers pointed out this could be due to changes in the gut microbiota and production of certain short-chain fatty acids after probiotics supplementation.
A total of 120 healthy adults experiencing mild stress took part in the randomised, double-blind, placebo-controlled trial, where they took either 1) 10bn CFU or 2) 50bn CFU of Lactobacillus paracasei 207-27 or 3) placebo after lunch for 29 days.
The strain Lactobacillus paracasei 207-27 originated from healthy infant faeces.
It has been commercialised as Lacticaseibacillus paracasei LPB27 by China health supplement giant BYHEALTH.
In previous in vitro and in vivo studies, it was found that the strain has good probiotic properties, and it has been considered a candidate probiotic strain.
To measure changes in their sleep quality, participants had to answer the Pittsburgh sleep quality index (PSQI) questionnaire, as well as wearing a Huawei B6 device during their sleep.
Their faecal samples and blood samples were also collected to measure their hormones levels, such as corticotropin-releasing hormone, adrenocorticotropic hormone, cortisol, γ-aminobutyric acid, and 5-hydroxytryptamine levels.
Findings showed that both groups that took probiotics had significant improvements in their sleep duration as compared to the placebo group.
Based on readings from the wearable device, the mean sleep duration was increased by 1.07 hours in the low-dose group and 1.04 hours in the high-dose group.
On top of sleep duration, the device also observed the number of awakenings during sleep, but no statistically significant differences were observed between the three groups.
On the other hand, there was also a significant reduction in PSQI scores among all three groups.
The PSQI measures a person’s subjective feeling on their sleep quality. The higher the scores, the poorer the sleep quality.
Gut-brain axis
The improvements seen among the probiotics groups could be due to the inhibition of the hypothalamic–pituitary–adrenal (HPA) axis activation, which subsequently lowered the levels of the stress hormone cortisol, said the researchers.
The HPA axis is a fundamental component of the gut–brain axis by orchestrating biological responses to stressful stimuli.
Aside from cortisol (COR), activities of the HPA axis were measured by the levels of other hormones, including corticotropin-releasing hormone (CRH) and adrenocorticotropic hormone (ACTH).
In this case, CRH regulates stress response by inducing the release of ACTH, which subsequently releases COR.
Results showed that CRH levels were significantly differences between the three groups.
In particular, CRH levels had slightly increased in the high-dose group but decreased in both low-dose and placebo groups – with a greater decrease seen in the placebo group.
On the other hand, ACTH levels had decreased in the low-dose group but went up in both the high-dose and placebo groups.
Also, levels of the stress hormone COR had significantly decreased in both probiotics groups but increased in the placebo group.
“Overall, daily consumption of L. paracasei 207-27 could inhibit HPA axis activation. These findings supported the notion that probiotics can reduce HPA activity consequently enhance sleep quality,” said the researchers.
Gut microbiome changes
Aside from changes in hormones levels, there were also changes in the gut microbiota and short-chain fatty acids which could have led to improvements in both probiotics groups.
For instance, the relative abundance of Lactobacillus was significantly increased in both probiotics group but decreased in the placebo group post intervention.
At the phylum level, the low-dose group also exhibited a higher relative abundance of Bacteroidota than the placebo group. It also showed a significantly lower Firmicutes-to-Bacteroidetes (F/B) ratio than the placebo group.
At the genus level, both probiotics groups had higher relative abundance of Bacteroides and Megamonas, alongside lower levels of Escherichia-Shigella.
No significant changes were observed in bacteria such as Enterococcus, Enterobacter, etc.
In terms of short-chain fatty acids (SCFA), the low-dose probiotics group reported significant increases in acetic acid, propionic acid, butyric acid, and valeric acid levels.
“In our study, the low-dose group exhibited greater changes in acetic acid, propionic acid, butyric acid, and valeric acid levels than the placebo group.
“The production of SCFAs involves a variety of bacteria and multiple pathways. Although this study did not identify a relationship between SCFAs and gut microbiota at the top 10 genus level, the increase in SCFAs content may be associated with changes in the abundance of multiple bacteria induced by the low dose of L. paracasei 207-27, particularly some low-abundance bacteria,” said the researchers.
Based on the findings, the researchers concluded that L. paracasei 207-27 supplementation could enhance sleep quality by modulating SCFA levels.
“L. paracasei 207-27 administration in healthy adults resulted in improvements in gut microbiota community and sleep duration.
“The mechanisms might involve modulation of the gut microbiota structure to regulate the function of the gut–brain axis, including increases in SCFA levels and decreases in hypothalamic–pituitary–adrenal axis activity.”
Source: Food and Function
Lacticaseibacillus paracasei 207-27 alters the microbiota–gut–brain axis to improve wearable device-measured sleep duration in healthy adults: a randomized, double-blind, placebo-controlled trial
DOI: 10.1039/d4fo01684j
Authors: Jinxing Li et al
