Gut microbiota can influence health through the microbiota–gut–brain axis. Meditation can positively impact the regulation of an individual’s physical and mental health. However, few studies have investigated fecal microbiota following long-term (several years) deep meditation. Therefore, this study tested the hypothesis that long-term meditation may regulate gut microbiota homeostasis and, in turn, affect physical and mental health.
To examine the intestinal flora, 16S rRNA gene sequencing was performed on fecal samples of 56 Tibetan Buddhist monks and neighboring residents. Based on the sequencing data, linear discriminant analysis effect size (LEfSe) was employed to identify differential intestinal microbial communities between the two groups. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) analysis was used to predict the function of fecal microbiota. In addition, we evaluated biochemical indices in the plasma.
The α-diversity indices of the meditation and control groups differed significantly. At the genus level, Prevotella and Bacteroides were significantly enriched in the meditation group. According to the LEfSe analysis, two beneficial bacterial genera (Megamonas and Faecalibacterium) were significantly enriched in the meditation group. The functional predictive analysis further showed that several pathways—including glycan biosynthesis, metabolism, and lipopolysaccharide biosynthesis—were significantly enriched in the meditation group. Moreover, plasma levels of clinical risk factors were significantly decreased in the meditation group, including total cholesterol and apolipoprotein B.
The Chinese authors concluded that the intestinal microbiota composition was significantly altered in Buddhist monks practicing long-term meditation compared with that in locally recruited control subjects. Bacteria enriched in the meditation group at the genus level had a positive effect on human physical and mental health. This altered intestinal microbiota composition could reduce the risk of anxiety and depression and improve immune function in the body. The biochemical marker profile indicates that meditation may reduce the risk of cardiovascular diseases in psychosomatic medicine. 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. This study provides new clues regarding the role of long-term deep meditation in regulating human intestinal flora, which may play a positive role in psychosomatic conditions and well-being.
This study is being mentioned on the BBC new-bulletins today – so I thought I have a look at it and check how solid it is. The most obvious question to ask is whether the researchers compared comparable samples.
The investigators collected a total of 128 samples. Subsequently, samples whose subjects had taken antibiotics and yogurt or samples of poor quality were excluded, resulting in 56 eligible samples. To achieve mind training, Tibetan Buddhist monks performed meditation practices of Samatha and Vipassana for at least 2 hours a day for 3–30 years (mean (SD) 18.94 (7.56) years). Samatha is the Buddhist practice of calm abiding, which steadies and concentrates the mind by resting the individual’s attention on a single object or mantra. Vipassana is an insightful meditation practice that enables one to enquire into the true nature of all phenomena. Hardly any information about the controls was provided.
This means that dozens of factors other than meditation could very easily be responsible for the observed differences; nutrition and lifestyle factors are obvious prime candidates. The fact that the authors fail to even discuss these possibilities and more than once imply a causal link between meditation and the observed outcomes is more than a little irritating, in my view. In fact, it amounts to very poor science.
I am dismayed that a respected journal published such an obviously flawed study without a critical comment and that the UK media lapped it up so naively.
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I saw this in the Guardian this morning and also found it very naive, though to be fair it seems the authors were also cautious. A group of monks are hardly the most representative people to study. Assuming they are following traditional Buddhist practice they will be eating a very simple, probably vegetarian, diet and probably taking no food at all after midday. No alcohol of course. Might this have a more significant impact on gut bacteria than the meditation?
Perhaps we need a control group of western mini-celebs who combine a bit of meditation with the average western excesses.
I did not find the authors’ statements cautious at all.
Maybe the Guardian gave more weight to the limitations than the original – it noted that the study was observational, limited in number and providing no conclusions.
So why bother publishing?
I hadn’t noticed it was yet another Chinese study.
@Socrates
Indeed, microbiome composition changes rapidly with diet.
https://www.scientificamerican.com/article/the-guts-microbiome-changes-diet/
Study design was very simplistic, all they did was compare microbial composition (monks vs non-monks) at single timepoint. In this case a longitudinal study with sampling at multiple timepoints is necessary to draw any decent conclusions between meditation and microbiome composition. At a minimum they should have taken baseline samples from all subjects and compared them with samples taken from the same group towards the end of the study, this will reveal any changes due to diet (or other factors) with in that group. I’d expect the monks to exhibit minimal changes due to their monk-ish lifestyle. But microbiome changes in non-monks might not be that straight forward and that may have eventually skewed the results, but we will never know due to poor study design. It is quite possible that meditation has little to no effect.