In a recent article published in General Psychiatry, researchers investigated the effects of long-term traditional Tibetan Buddhist meditation on the gut microbiome's structural characteristics. Additionally, the researchers screened microbes in the gut microbiota for insights into their biochemical indices and functionality.
Study: Alteration of faecal microbiota balance related to long-term deep meditation. Image Credit: Lia_Tsvet/Shutterstock
Background
Studies have shown how gut microbiota influence health through the microbiota–gut–brain axis. However, there is a shortage of studies investigating the fecal microbiota of individuals practicing deep meditation over several years.
Meditation, a form of psychological training with roots in ancient Indian Ayurveda, allows self-regulation of the body, which, in turn, positively impacts one's physical and mental health.
About the study
In the present study, researchers proposed that deep meditation over a prolonged duration could help regulate gut microbiota homeostasis, positively affecting one's physical and mental health.
They collected a total of 128 samples, including fecal and peripheral venous blood samples from Tibetan Buddhist monks, of which they used only 56 samples for the study analysis (meditation group). They excluded 68 samples from subjects who consumed antibiotics and yogurt and four other samples due to poor quality. They transported collected samples stored at −80 °C to the Shanghai Mental Health Centre in China for study analysis.
The researchers used these samples for 16S ribosomal ribonucleic acid (rRNA) gene amplicon sequencing and analysis. They generated fastq-files for downstream analyses from the sequencing output. After eliminating redundancy from the assembled 16S tags, they clustered tags with more than one frequency in operational taxonomic units (OTUs). All OTUs had a representative 16S tag, to which the team assigned a taxon using the Ribosomal Database Project (RDP) Classifier (confidence threshold equals 0.8). The researchers used QIIME version 1.9.1 for OTU profiling and α- and β-diversity analyses.
Furthermore, the team used the t-test and Mann–Whitney U tests to analyze normally and non-normally distributed variables. They considered a p-value of <0.05 as statistically significant.
The researchers performed linear discriminant analysis (LDA) to identify bacteria differentially expressed in the two study groups. Finally, they deployed the PICRUSt software to infer the abundance of the Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathways. It helped the researchers explore the altered function of fecal microbiota in the two study groups and reconstruct the unobserved states of microbial communities for their phylogenetic examination.
Study findings
The test group comprised 37 Tibetan Buddhist monks, all males, and the control group had 19 age-matched residents, with all having similar diets, smoking, and alcohol consumption. These monks had been performing practices of Samatha and Vipassana for a minimum of two hours every day for three to 30 years, on average for 7.56 years, and all had comparable age, blood pressure, and heart rate.
The study analysis helped identify 803 OTUs after the taxonomic assignment, of which 611 were shared between the meditation and control groups, whereas 91 and 101 were unique. Moreover, taxonomic rank abundance curves exhibited similar patterns of relative bacterial evenness across all samples. However, the α-diversity of the gut microbiome was markedly higher in the controls, per Alpha diversity indices.
The team computed β-diversity, a distance distribution heatmap, ANOSIM, and Principal Coordinates Analysis (PCoA) using the weighted UniFrac method. Its results revealed that the gut microbiome of the meditation group assembled father from the control group. The researchers noted that the meditation group had more microbes from phyla Bacteroidetes and family Prevotellaceae, whereas Firmicutes phyla and families Ruminococcaceae, Veillonellaceae, and Lachnospiraceae were dominant in both groups. At the genus level, the meditation group had higher proportions of Prevotella and Bacteroides than the control group, 42.35% and 6.21% vs. 29.15% and 4.07%.
Also, compared to controls, the meditation group members had significantly higher levels of Megamonas and Faecalibacterium. While studies have associated the former bacterial genera with psycho-cognitive traits, the latter is shown to be associated with a higher quality of life. PICRUSt analysis revealed marked variances in the richness of KEGG pathways between the two study groups. The meditation group had enriched glycan and lipopolysaccharide biosynthesis pathways. Also, they showed significant enrichment in toluene degradation and adipocytokine signaling pathways.
The enrichment of these pathways showed the positive effects of meditation on the nervous system through the gut microbiota. Furthermore, plasma biochemical indices uncovered that the control group had higher total cholesterol and apolipoprotein B levels, which decreased their immune function and increased the risk of heart and lung diseases.
Conclusions
Overall, the gut microbiome in the meditation group substantially varied from the control group. Likewise, several bacterial species differed between the two groups, especially several bacteria associated with decreasing mental illnesses, suggesting that meditation influenced bacteria playing a role in mental health. The study findings further validated that the altered gut microbiota could reduce the risk of depression/anxiety and improve immunity. Together, these results suggested that meditation positively impacted psychosomatic conditions and overall well-being. Therefore, according to the authors, future research must explore the effectiveness of meditation in psychosomatic diseases.
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