An ever-growing body of evidence supports the importance of the gut-brain axis in linking emotional and cognitive centers in the brain with the enteric nervous system that governs the function of the gastrointestinal tract. Recent advances in research have suggested that there is communication between the gut microbes and the gut-brain axis, and vice versa, by means of neural, endocrine, and immune system links.
A healthy gut microbiome is involved in overall health and wellbeing in people, and has been shown to affect human metabolism, nutrition, physiology, and immune function. Conversely, imbalance in the normal gut microbiota (dysbiosis) has been linked with gastrointestinal conditions such as inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS), as well as mental health issues such as depression, anxiety and autism.
The practice of meditation has also been shown to influence physical, emotional and mental health in people, and it is increasingly incorporated into treatment programs for those suffering psychological distress associated with depression, anxiety, substance abuse, pain, eating disorders and trauma. Deep meditation is known to originate from ancient Indian Ayurveda, and is today practiced by Tibetan Buddhist monks as a form of psychological training. The practice exercises the mind and allows self-regulation of the body, to cultivate wellbeing and provide insights into the true nature of all phenomena.
However, no research has yet been conducted that links the practice of deep meditation with changes in the structure and function of the gut microbiome.
In an attempt to find out whether meditation can influence the gut microbiome, researchers based at the Shanghai Mental Health Center in Shanghai, China, collected fecal and blood samples from 37 Tibetan Buddhist monks from three temples, and compared them with samples from 19 secular residents in areas surrounding the temples.
The monks had all been practicing deep meditation for at least two hours a day, over a period of between three and thirty years. It was a logistical challenge for researchers to collect these samples, due to the isolated and remote conditions in the Tibetan mountains. Despite this, the researchers had to discard many samples from monks and secular participants who had recently taken antibiotics, probiotics, prebiotics or antifungal drugs, or who had eaten yogurt, as these substances can alter the quantity and diversity of gut microbes.
Once the fecal samples were analyzed for genetic material from microbes, the researchers found significant differences in the diversity and volume of microbes in the guts of the monks and their neighbors. The results, published in the journal General Psychiatry, show that the control group (secular neighbors) had a greater diversity of species present in the gut microbiome, than did the monks. While the two groups shared 611 out of 803 different microbe species in their fecal samples, the meditation group had an additional, unique 91 species whereas the control group had 101 additional unique species.
Both groups were matched for age, blood pressure and heart rate. In addition, the two groups had the same dietary structure, with staple foods that included highland barley, rice, steamed bread and noodles. Supplementary food primarily comprised vegetables, meat and butter tea.
The authors report that, at the genus level, Prevotella, Bacteroides, Dialister, Roseburia and Faecalibacterium were the predominant microbes in both ample sgroups. In addition, Bacteroidetes were found to be significantly enriched in samples from the meditation group (29 percent vs 4 percent), which also contained more abundant Prevotella (42 percent vs 6 percent) species, and a high volume of Megamonas and Faecalibacterium species.
These groups of microbes are known to be beneficial to gut health. In addition, previous research has indicated that species of Prevotella, Bacteroidetes, Megamonas and Faecalibacterium have been associated with the alleviation of mental illness symptoms.
“Collectively, several bacteria enriched in the meditation group [have been] associated with the alleviation of mental illness, suggesting that meditation can influence certain bacteria that may have a role in mental health,” write the researchers.
The researchers then applied an advanced analytical technique to predict which chemical processes the microbes might be influencing. Their results suggested that several protective anti-inflammatory pathways, in addition to metabolic pathways – the conversion of food into energy – were enhanced in the meditating monks.
Finally, blood sample analysis showed that levels of chemical agents, including total cholesterol and apolipoprotein B, were significantly lower in the samples from the monks than in their secular neighbors. These biomarkers have previously been associated with decreased immune function and heightened risk of cardiovascular disease.
There are some limitations to this study; it is a comparative study, based on observations of a small, all-male group of participants that all lived at high altitude. This means the conclusions may not be generalizable to the public at large. In addition, no measurements were made of the potential health implications of these differences in gut microbiome, the researchers referring instead to results from other studies for this information.
However, the researchers suggest that their findings show long-term, deep meditation may have a beneficial effect on gut microbiota, enabling the body to maintain an optimal state of health, both physical and mental.
The study authors state that the role of meditation in helping to prevent or treat psychosomatic illness definitely merits further research. “These results suggest that long-term deep meditation may have a beneficial effect on gut microbiota, enabling the body to maintain an optimal state of health.”
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