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• Response to " Controlling for diet and BMI differences"
  Jinghong Chen
  Published on: 5 April 2023
• Controlling for diet and BMI differences
  Matt L Jones
  Published on: 8 February 2023
• Do monks differ from the local population in other factors besides meditation？
  Hean T Ong
  Published on: 17 January 2023

• Published on: 5 April 2023

  Response to " Controlling for diet and BMI differences"

  • Jinghong Chen, Professor, Executive editor Professor in Shanghai Key Laboratory of Psychotic disorders Executive editor of General Psychiatry Shanghai Mental Health Center

  We are delighted that you are interested in our study. In terms of diet, we mainly recorded the usual diet and the diet from the past 24 hours. We found that the diet structure was consistent, but we did not further quantify the relative amount of food you mentioned. Regarding BMI, although we collected the same sample as the previous study, the selecting sample number is a different and we ended up selecting only a fraction of the original samples according to the strict sample collecting rule's limitation, therefore, some BMI values were missing and thus not complete analyzed in the article. Partly Data ANCOVA analysis Result showed no difference. The high altitude and small population of Tibet, combined with communication barriers, made it challenging to collect the sample. Therefore, we could not follow the strict inclusion and perfect criteria to collect the sample. However, as a preliminary study on the relationship between meditation and intestinal bacteria, our findings shed some light on the subject. It still is also good to bring some enlightenment to the field.

   

  Reference: Xue T, Chiao B, Xu T, et al. The heart-brain axis: a proteomics study of meditation on the cardiovascular system of Tibetan monks. EBioMedicine 2022;80:104026.

  Conflict of Interest:
  None declared.

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• Published on: 8 February 2023

  Controlling for diet and BMI differences

  • Matt L Jones, Postdoctoral Research Fellow University of Exeter

  Dear authors,

  Thank you for your interesting study on the effect of meditation on the faecal microbiota. The paper itself states that "...both [control and meditation] groups had the same dietary structure. The staple food mainly included highland barley, rice, steamed bread and noodles, and the supplementary food primarily comprised vegetables, meat and butter tea.'", but no other information or data is provided.

  In your reply to Dr Ong’s Rapid Response, you helpfully point readers interested in this question to the supplementary tables of your previously published paper using the same participants (1), with Supplementary Table 7 being the most relevant here. However, after examining the table and the other information provided in both papers, it is still unclear to me how diet was controlled for. The implication from the table is that participants in the Monk and Control groups were simply asked, in a qualitative way, whether or not various food groups were included in their daily diet. This information does not seem sufficient to use to control for diet, since the food groups participants about which participants were asked are very broad (e.g. highland barley, rice, noodles) - meaning that participants are likely to include/not include similar groups in their diet, even as the relative quantities of each food group that they consume may differ substantially. Could you please clarify how information about participants’ diet was recorded, and...

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  Dear authors,

  Thank you for your interesting study on the effect of meditation on the faecal microbiota. The paper itself states that "...both [control and meditation] groups had the same dietary structure. The staple food mainly included highland barley, rice, steamed bread and noodles, and the supplementary food primarily comprised vegetables, meat and butter tea.'", but no other information or data is provided.

  In your reply to Dr Ong’s Rapid Response, you helpfully point readers interested in this question to the supplementary tables of your previously published paper using the same participants (1), with Supplementary Table 7 being the most relevant here. However, after examining the table and the other information provided in both papers, it is still unclear to me how diet was controlled for. The implication from the table is that participants in the Monk and Control groups were simply asked, in a qualitative way, whether or not various food groups were included in their daily diet. This information does not seem sufficient to use to control for diet, since the food groups participants about which participants were asked are very broad (e.g. highland barley, rice, noodles) - meaning that participants are likely to include/not include similar groups in their diet, even as the relative quantities of each food group that they consume may differ substantially. Could you please clarify how information about participants’ diet was recorded, and whether or not a more quantitative measure was used, providing additional (anonymised) data to support this?

  In a potentially related issue, when comparing differences between Monk and Control groups, the previous paper actually finds that BMI is significantly higher in Monks (i.e. they are clinically obese on average). Although this was statistically controlled for in the previous analysis/paper, BMI differences are not even mentioned in the current paper. Could you please clarify how BMI differences were accounted for in the current paper?

  Thank you for taking the time to consider my request.

  Yours sincerely,

  Dr Matt Lloyd Jones

  1. Xue T, Chiao B, Xu T, et al. The heart-brain axis: a proteomics study of meditation on the cardiovascular system of Tibetan monks. EBioMedicine 2022;80:104026.

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  Conflict of Interest:
  None declared.

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• Published on: 17 January 2023

  Do monks differ from the local population in other factors besides meditation？

  • Hean T Ong, Consultant Cardiologist HT Ong Heart Clinic, Penang, Malaysia

  Sun and colleagues compared the faecal microbiota of 37 Tibetian monks with 19 ordinary residents nearby to conclude that meditation favorably affected gut microbiota to have a positive effect on health. However, monks in a temple may differ from ordinary lay residents in other ways besides the practice of meditation. While monks are strict vegetarians, lay people are under no such obligation. Life in a temple is also more sheltered and less stressful when compared to that of ordinary people living in a harsh, high altitude environment. To show that it is meditation which causes the favorable faecal microbiota, the researchers would have to test the monks after a meditation free period, or else subject their lay controls to a period of intense mediation to see if there is any change in fecal microbiota afterwards. In selecting non monks who may be different as their controls, the researchers can be justified in concluding that monastic life favorably influences gut microbiota, but are not justified in attributing the change solely to meditation.

  Reference:
  Sun Y, Ju P, Xue T, et al. Alteration of faecal microbiota balance related to long-term deep meditation. General Psychiatry 2023;36:e100893. doi: ‪10.1136‬/gpsych-2022-100893

  Hean T Ong, FRCP, FACC, FESC
  Consultant Cardiologist, HT Ong Heart Clinic, Penang, Malaysia

  Reply：

  Thank you for your letter and interest in our study. We would like to make some clarification in reply to the...

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  Sun and colleagues compared the faecal microbiota of 37 Tibetian monks with 19 ordinary residents nearby to conclude that meditation favorably affected gut microbiota to have a positive effect on health. However, monks in a temple may differ from ordinary lay residents in other ways besides the practice of meditation. While monks are strict vegetarians, lay people are under no such obligation. Life in a temple is also more sheltered and less stressful when compared to that of ordinary people living in a harsh, high altitude environment. To show that it is meditation which causes the favorable faecal microbiota, the researchers would have to test the monks after a meditation free period, or else subject their lay controls to a period of intense mediation to see if there is any change in fecal microbiota afterwards. In selecting non monks who may be different as their controls, the researchers can be justified in concluding that monastic life favorably influences gut microbiota, but are not justified in attributing the change solely to meditation.

  Reference:
  Sun Y, Ju P, Xue T, et al. Alteration of faecal microbiota balance related to long-term deep meditation. General Psychiatry 2023;36:e100893. doi: ‪10.1136‬/gpsych-2022-100893

  Hean T Ong, FRCP, FACC, FESC
  Consultant Cardiologist, HT Ong Heart Clinic, Penang, Malaysia

  Reply：

  Thank you for your letter and interest in our study. We would like to make some clarification in reply to the points you raised.

  Since lifestyle may contain confounding factors when investigating the effects of meditation, our study aimed to minimize the impact of lifestyle factors in this investigation of the effects of meditation. To achieve this, we strictly matched age, sex, smoking, alcohol, and dietary habits between the monk and Tibetan control groups. Tibetian monks are not strict vegetarians so that all our participants, monks and controls, consumed a similar diet mainly of highland barley, rice, steamed bread, noodles, and other staple foods, supplemented with vegetables, meat, and butter tea. This information can be found in section 3.1 of our article, as well as in the supplementary tables of our previously published paper (1,2).

  Tibetan Buddhism and Tibetan lifestyle deeply influence each other and are closely connected so that the daily life of the monks and the lay people in our study are similar. Both groups come from the same community and maintain social connections with their nearby families. While the lay controls often work in physically demanding jobs, the monks have to undertake equally hard physical work to maintain their temple premises in a similarly high altitude harsh environment. Additionally, both the monks and Tibetan controls of this area generally are subjected to low levels of mental stress.

  While we acknowledge that there may be some other differences in the lifestyles of monks and lay Tibetans, the biggest difference is in the time spent in meditation. Therefore, the changes we observed in gut microbiota are very likely to be specifically associated with the practice of meditation.

  There are practical limitations to consider in trying to implement the suggestions proposed . For the monks, meditation is a daily and mandatory practice, making it impossible to discontinue. Furthermore, for lay people it would be impossible to achieve the level of sophistication and depth of meditation that the monks have developed over many years of practice.

  However, this is only a preliminary study and further research is necessary to gain a deeper understanding of the effects of medication and its underlying mechanisms. We welcome further discussion and interest in this topic and hope that future studies will provide additional insights.

  References:
  1. Xue T, Chiao B, Xu T, et al. The heart-brain axis: a proteomics study of meditation on the cardiovascular system of Tibetan monks. EBioMedicine 2022;80:104026.
  2.Sun Y, Ju P, Xue T, et al. Alteration of faecal microbiota balance related to long-term deep meditation. General Psychiatry 2023;36:e100893. doi: ‪10.1136‬/gpsych-2022-100893

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  Conflict of Interest:
  None declared.

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