Effect of a Two-Week Diet without Meat and Poultry on Serum Coenzyme Q10 Levels
Round 1
Reviewer 1 Report (Previous Reviewer 2)
Comments and Suggestions for Authors
I thank the authors of the manuscript "Effect of a 2-week diet without meat and poultry on serum coenzyme Q10 levels" for their work and for reporting it in their manuscript. This study investigated the effect of a 2-week meat/poultry-restricted diet trial on change in serum CoQ10 levels in young Japanese women majoring in nutrition/dietetics.
While this study presented a limited number of cases (22), it was conducted using an appropriate methodology.
This manuscript has already been revised. The changes the authors have made for this further request appear consistent and adequate compared to what was suggested and asked of the authors in the first revision.
Reviewer 2 Report (Previous Reviewer 1)
Comments and Suggestions for Authors
The author of the manuscript submits an edited version in which he has accepted or incorporated all my comments and suggestions to the maximum extent.
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
Dear Author,
after studying your manuscript, I must recognize the importance of monitoring the effect of reducing the intake of meat and poultry as a food source of CoQ10 on health indicators. The concept and design of the study are in accordance with the requirements, however, from the methodological side, I see serious shortcomings that you mention in the limitations. If we want to draw conclusions, we must start from real data, not estimated. I appreciate your effort to calculate macronutrient and micronutrient intake, but a method of estimating intake based on food weighing and software calculation of nutrient intake as well as CoQ10 would be more appropriate for a publication of this type.
In the methodological part, I would also be interested in what the exclusion criteria were for the selection of female volunteers and if you could also describe the methods of anthropometric measurements. When mentioning fats or proteins of non-animal origin, use the term vegetable fat or protein, not plant.
In Table 2, in the third column, report the p-value for CoQ10 in a different way.
The study population is small. Therefore, the statistical power of the study is questionable. What is the number of participants presented by the power analysis?
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for Authors
I thank the authors of the manuscript "Effect of a 2-week diet without meat and poultry on serum coenzyme Q10 levels" for the work they have done and for reporting it in their manuscript. This study investigated the effect of a 2-week meat/poultry-restricted diet trial on change in serum CoQ10 levels in young Japanese women majoring in nutrition/dietetics.
The study presents a limited case study, only 22 subjects, all women.
In methods, I suggest the authors also describe how the anthropometric parameters were collected.
I ask the authors to review and correct the "p" of the p value throughout the text, tables and figures (including legend/note of figures). The "p" of the p value (or p-value) must always be written with a lowercase letter (it must not be written with a capital letter!).
I ask the authors to revise and correct the following text:
Line 44: CoQ10 = CoQ10 (You put the 10 to pedic)
Line 210: 0g = 0 g
Line 228/229 and Line 236/238: Basically, the text of the manuscript bears the same concept, which becomes repetitive.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for Authors
Summary of manuscript: This study investigated the consumption of a 2-week diet (without meat or poultry) on serum CoQ10 concentrations in 22 young women. It was demonstrated that the average serum reduced, oxidized, and total CoQ10 levels decreased after the dietary intervention. It was concluded that meat and poultry are significant sources of CoQ10. Furthermore, individuals who adhere to long-term diets with lower serum CoQ10 concentrations, such as vegetarian and vegan diets, might need CoQ10 supplementation.
General comments: I carefully reviewed this manuscript. The author provided a study with very interesting results. I commend the author for a timely investigation. I recommend additional clarifications regarding the study design and dietary assessment methods. I provided my specific comments below.
Materials and Methods
Can you please clarify the original prospective interventional study that was conducted in 2015 and 2016 and this current study that was performed in 2023 and 2024? Were the same participants from 2015 and 2016 contacted again for this current study? What specifically was performed and analyzed in this current study? Please include these topics in the materials and methods section.
Results
Table 2: According to Table 2, animal protein and fat were consumed during the 2-week intervention. What were the dietary sources of animal protein and fat?
Lines 146-147: It was stated that EPA and DHA increased, suggesting an increased fish intake. Did you determine the specific food items consumed via the questionnaire?
Were vitamin and mineral intakes analyzed? Were there any significant differences?
Was there a group that consumed meat and poultry for comparison purposes?
Discussion
Lines 168-169: It was mentioned that changes in eating habits impact both dietary intake and blood levels of CoQ10. What were the specific dietary changes (macronutrients and micronutrients)? Were supplement intakes accounted for?
How do you know that the reduced CoQ10 levels are due to only restricting meat and poultry?
Are you confident that the participants did restrict meat and poultry?
Did the questionnaires confirm these findings?
Could other dietary differences result in reduced CoQ10 levels?
Lines 207-215: Can you please compare this section to the section in materials and methods (lines 75-85)? The reader is likely going to be confused regarding specifically how the dietary intakes were assessed (e.g. 1-month diet recall versus completing the BDHQ twice on the day of blood collection). Please provide additional clarifications in the manuscript.
Line 215: Which “nutrition management software” was used? Which nutrients were analyzed?
Line 248: It is indicated that this current study “re-used previous data from a prospective interventional study.” In my opinion, this attribute is causing confusion regarding what occurred in this current study versus what happened in the previous study. Therefore, please address the above comments to improve the clarity of the manuscript.
Comments on the Quality of English Language
Minor editing of English language is recommended.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for Authors
I thank the author for accepting comments and suggestions, as well as for proofreading the text. Based on the review of the revised manuscript and the completion of the requested information, I am convinced that the manuscript has been improved and is suitable for publication.
Author Response
Thank you very much for taking the time to comment and review.
Reviewer 3 Report
Comments and Suggestions for Authors
I would like to thank the author for revising the manuscript. Unfortunately, I have concerns regarding the measurements of the dietary and supplement patterns of the participants.
Comments on the Quality of English Language
Minor editing is recommended.
Author Response
I would like to thank the author for revising the manuscript. Unfortunately, I have concerns regarding the measurements of the dietary and supplement patterns of the participants.
I thank the reviewer for his/her helpful suggestions for improving my manuscript. I revised the manuscript whenever possible in response to the reviewer’s comments. Changes in the manuscript are yellow-highlighted. I believe the changes requested by the reviewer have significantly improved our manuscript. I hope that the paper will now be acceptable for Dietetics.
I understand your point; however, to reduce the burden on participants, I didn’t use a method of estimating intake based on food weighing and software calculation of nutrient intake in this study. Instead, I used a simplified method to estimate CoQ10 intake developed based on our previous research findings [reference No. 10], in which food weighing and software calculation of nutrient intake were performed (Lines 79-80). Also, a BDHQ was employed to estimate macronutrient and micronutrient intake (Lines 80-84). In addition, in response to the reviewer's concerns, I have described the study's limitations in lines 221-233. I believe my conclusion that meat and poultry consumption restriction leads to decreased serum CoQ10 levels is concrete and precise, regardless of which nutrient intake estimation method is used.
Additionally, in response to reviewer comments regarding the first round of reviews, I revised the Materials and Methods section in lines 77-79, 84-86, and 97-101 to avoid confusion for readers.
