Review Reports

Response to Reviewer 1 Comments

1. Summary

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.

2. Questions for General Evaluation

Reviewer’s Evaluation

Response and Revisions

Does the introduction provide sufficient background and include all relevant references?

Must be improved

Please refer to our detailed response in the Point-by-Point Response Letter below.

Is the research design appropriate?

Yes

Are the methods adequately described?

Must be improved

Are the results clearly presented?

Must be improved

Are the conclusions supported by the results?

Are all figures and tables clear and well-presented?

Yes

Yes

3. Point-by-point response to Comments and Suggestions for Authors

Comments 1: The authors left placeholders (e.g. in the introduction, and the Suppl Materials Figure S1: title; Table S1: title; Video S1: title) this needs to be fixed.

Response 1:

Thank you for your valuable comment. We have removed all placeholders in the manuscript. With your helpful feedback, the manuscript has been further refined to ensure completeness and clarity.

Comments 2: is ref#8 correct?? the topic of the paper cited in reference 8 is about pediatric acute myeloid leukemia, not about hepatic steatosis and bone health as cited in the text.

Response 2:

Thank you for pointing this out. We agree with this comment and sincerely apologize for this careless citation error in the manuscript. Therefore, we have removed the incorrect reference #8 and replaced it with a highly relevant recent study focusing on hepatic steatosis and bone health in pediatric populations, with the corresponding revisions made at Line 428 in the manuscript. Meanwhile, we have carefully checked all other references in the manuscript to ensure the accuracy and relevance of each citation, and all revisions have been updated in the resubmitted files.

Comments 3: The introduction is rather short and jumps directly into the topic without the context that the template instructions from mdpi call for. While the content is adequate, it could be more comprehensive by providing broader context about childhood bone health. Also it would benefit from stating the study's specific aims and hypotheses with more clarity

Response 3:

Thank you for your valuable comment. We fully agree with your suggestions regarding the introduction section. In response to your feedback, we have thoroughly revised and expanded the introduction: we have enriched the research context as required by the MDPI template, supplemented more comprehensive background information related to childhood bone health to enhance the completeness of the discussion, and clearly clarified the specific aims and hypotheses of this study. All the revised contents have been highlighted in red in the introduction section of the revised manuscript for your convenient review.

Comments 4: In the methods the MAFLD diagnostic criteria are complex and could be presented more clearly, perhaps in a table or flowchart?

Response 4:

Thank you for your valuable comment. We fully agree with your suggestion that the MAFLD diagnostic criteria in the methods section could be presented more clearly. In response to your feedback, we have reorganized the complex MAFLD diagnostic criteria and supplemented them as Table 1 in the revised manuscript, which makes the diagnostic criteria more intuitive and easier to understand. The corresponding revisions have been completed in the methods section of the manuscript for your review.

Comments 5: Table 1 is a bit too dense. Not sure if the authors can split it in two or put parts of it in the Supplements?

Response 5:

Thank you for your valuable suggestion. We have split Table 1 into two separate tables in the revised manuscript to address the density issue, which makes the presentation of data clearer and more readable for readers.

Comments 6: Discussion: The mechanism section is somewhat speculative without supporting data from this study

Response 6:

Thank you for your valuable comment. We fully agree with your suggestion that the mechanism section in the original manuscript was somewhat speculative due to the lack of supporting data from this study. To address this issue, we have thoroughly revised, condensed, supplemented, and rewritten the entire mechanism discussion section in the revised manuscript.

We have removed overly speculative descriptions that were not supported by our study’s data, retained and refined the mechanistic insights that are closely related to our research findings, and supplemented reasonable inferences that are consistent with existing high-quality literature. The revised section focuses more on linking the mechanism discussion to our study’s results and avoids unfounded speculation, ensuring that the mechanistic analysis is more prudent, objective, and closely aligned with the actual data of this study.

All revisions have been completed to enhance the rigor and credibility of the discussion, and all revised content has been highlighted in red in the discussion section for your easy review. We greatly appreciate your guidance in improving the quality of this section.

4. Response to Comments on the Quality of English Language

Point 1:The English is generally good but some sentences are overly long and complex.

Response 1:

Thank you for your constructive comment on the language quality. We have carefully revised all overly long and complex sentences in the manuscript by splitting and simplifying them, while ensuring the accuracy and coherence of the academic expression. All these language revisions have been highlighted in the revised manuscript for your easy reference.

5. Additional clarifications

All relevant information has been addressed in the preceding responses, so no additional clarifications are needed.

Response to Reviewer 2 Comments

1. Summary

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.

2. Questions for General Evaluation

Reviewer’s Evaluation

Response and Revisions

Does the introduction provide sufficient background and include all relevant references?

Must be improved

Please refer to our detailed response in the Point-by-Point Response Letter below.

Are all the cited references relevant to the research?

Is the research design appropriate?

Can be improved

Are the methods adequately described?

Must be improved

Are the results clearly presented?

Can be improved

Are the conclusions supported by the results?

Must be improved

Are all figures and tables clear and well-presented?

Must be improved

3. Point-by-point response to Comments and Suggestions for Authors

Comments 1: The country or location of the study should be included in the title.

Response 1:

Thank you for your valuable suggestion. We agree with this comment and have revised the title by adding the study location. The revised title is: Metabolic Dysfunction-Associated Fatty Liver Disease and Bone Mineral Density in School-Aged Children in China: A Propensity Score-Matched Analysis. This revision has been made in the revised manuscript.

Comments 2: Line 17-29; Line 32-44: There are too many methodological and results details; I would suggest condensing it into fewer details. 

Response 2:

Thank you for pointing this out. We agree with this comment. Therefore, we have condensed the excessive methodological and results details in the specified sections (Line 17-29; Line 32-44 of the original abstract) by retaining only core information, removing redundant technical descriptions, and streamlining data presentations while maintaining scientific rigor. This revision, highlighted in red, can be found in the Abstract section of the revised manuscript (Abstract, Line 17-42).

Comments 3: The date of sampling took place should be clearly stated in abstract.

Response 3:

Thank you for pointing this out. We agree with this comment. Therefore, we have clearly added the sampling period in the Abstract section of the revised manuscript. The sampling was conducted between September 2022 and May 2023. This information, highlighted in red, is included in Line 19.

Comments 4: Line 46-50: A specific direction for further research should be suggested in the conclusion. 

Response 4:

Thank you for your valuable comment. We fully agree with this suggestion and have supplemented specific directions for further research in the conclusion section of the abstract. Specifically, we have added the following content: "This highlights the importance of early MAFLD identification and targeted interventions to mitigate long-term skeletal risks. Prospective studies are needed to clarify the causal pathways between MAFLD and pediatric bone health, and future research should integrate multi-factors to elucidate the underlying mechanisms." These revisions clearly propose prospective studies for causal verification and multi-factor integrated mechanism exploration as key directions for future research, addressing the comment effectively. The revised abstract has been updated in the resubmitted manuscript(Line 46-50, highlighted in red).

Comments 5: Line 55-65: Should be deleted- it seems like comments.

Response 5:

Thank you for your comment. We agree with this suggestion and have deleted the content in Lines 55-65 of the manuscript as requested. The relevant revision has been completed in the resubmitted version of the manuscript.

Comments 6: The introduction is very brief and does not adequately address the purpose of the study. The literature should go into greater detail and address the connections between bone mineral density and metabolic dysfunction-associated MAFLD. This section should conclude with a description of the study's uniqueness and/or relevance. What does the research contribute to the body of literature?

Response 6:

Thank you for your valuable comment on the Introduction. We have expanded the literature review. We also explicitly stated the research gaps, study purpose, and highlighted our unique contributions. All revisions are highlighted in red in the manuscript.

Comments 7: Line 105-109: Participant recruitment should be described in much more details.

Response 7:

Thank you for this valuable comment. We agree that the participant recruitment process required more detailed description. Therefore, we have supplemented relevant information in the revised manuscript: participant recruitment was conducted using a stratified cluster sampling method within one administrative district of Beijing, ensuring the representativeness of the target population in the region. This supplementary content can be found in Line 106-108.

Comments 8: Line 128-131: There is a weak description of the development and validation of a questionnaire. What were the accuracy and consistency of this questionnaire? How the questionnaire was distributed?  

Response 8:

Thank you for your valuable comment on the questionnaire description. We appreciate your reminder to clarify the details of the questionnaire, which helps improve the rigor and transparency of our study. Here is the detailed response and revised content:

The structured questionnaire used in this study was developed by experienced clinicians and researchers in the field of pediatric nutrition and public health, drawing on the research experience and questionnaire frameworks from our previous related studies.

Regarding the implementation process: Prior to questionnaire distribution, written informed consent was obtained from all participating children’s parents or guardians. The questionnaire was self-reported by the children jointly with their parents/guardians to ensure the accuracy of information (especially for younger children aged 7-10 years). For dietary habits, the questionnaire adopted a food frequency recall method to collect information on the frequency and approximate intake of major food groups over the past month. Information on moderate-to-vigorous physical activity, screen time, and sleep duration was collected through self-reported recall of typical weekly patterns.

We have revised the corresponding part of the manuscript to incorporate these details(Line 130-139). Thank you again for your constructive feedback.

Comments 9: Line 132-190: The data collection procedure is not clearly described in detail. 

Response 9:

Thank you for this valuable comment. We agree that the data collection procedure needed more detailed description. Therefore, we have supplemented the details regarding informed consent in the revised manuscript: we clarified that anthropometric measurements and clinical examinations were only conducted for participants who had signed the informed consent form. These supplementary details can be found in Line 140-193 of the revised manuscript.

Comments 10: Line 192-207: It would be beneficial to evaluate and demonstrate the normality of the variables, as this may also influence the method of regression analysis.

Response 10:

Thank you for your valuable comment regarding variable normality evaluation. We have conducted normality tests for continuous variables including BMI, waist circumference (WC), and speed of sound (SOS). Although the statistical tests indicated non-normal distribution (attributed to the large sample size of our study), the graphical plots of these variables showed symmetric distributions.Given this, the non-normality did not affect the validity of our regression analyses.

Comments 11: All tables should be clearly organized. 

Response 11:

Thank you for this comment. We agree that all tables need clear organization. Therefore, we have split Table 1 into two separate tables in the revised manuscript to address its excessive length and improve readability. In addition, all other tables and figures have been reorganized and formatted for clearer presentation.

Comments 12: Clear justification why analysis was carried out according to gender. 

Response 12:

Response: Thank you for this insightful comment. Regarding the justification for conducting gender-stratified analysis, it is reasonable and necessary based on our team’s previous research (Li T, Huang G, Hou D, et al. A Comprehensive Analysis of Bone Mineral Density Changes across the Lifespan: Insights from National Surveys. Nutrients. 2024;16(16):2804. Published 2024 Aug 22. doi:10.3390/nu16162804). This prior study, using NHANES data, demonstrated significant inherent differences in bone mineral density between males and females. Therefore, gender-stratified analysis was performed to avoid potential confounding effects caused by these inherent gender differences and to ensure the validity and accuracy of the study results.

Comments 13: The discussion has to be rearranged because it is unclear what the study's findings and those of the other research the authors compared with. Each paragraph must conclude with a discussion.

Response 13:

Thank you for your valuable comment on the Discussion section. We fully agree that clarifying the distinction between our study’s findings and those of previous research, as well as adding clear concluding statements for each paragraph, is crucial to improving the manuscript’s clarity and rigor. In response, we have thoroughly rearranged the Discussion section. All revisions have been highlighted in red in the manuscript for easy reference.

Comments 14: Limitations of the study are acknowledged but with less details. 

Response 14:

Thank you for your valuable comment. We fully agree that the limitations section needed more detailed elaboration. Accordingly, we have substantially expanded and refined the discussion of the study’s limitations in the revised manuscript (Lines 367–379), providing more specific and in-depth descriptions to better reflect the potential constraints of the research. This supplement enhances the transparency and rigor of the manuscript, and we greatly appreciate your guidance in strengthening the completeness of our work.

Comments 15: I would suggest merging “Future Research Directions” (Section 4.6) with “Conclusions” (Section 5). 

Response 15:

Thank you for this valuable suggestion. We fully agree with merging the "Future Research Directions" (Section 4.6) with "Conclusions" (Section 5) to improve the logical coherence and conciseness of the manuscript. We have successfully merged the content of these two sections into a single "Conclusions" section in the revised manuscript, and the merged content can be found in Lines 381-392.

Comments 16: Line 390-502: Follow the journal guidelines for references. Please also update the outdated references (#18, 43).

Response 16:

Thank you for your valuable comment. We have carefully reviewed the reference section (Lines 390–502) and made revisions in strict accordance with the journal’s guidelines. Additionally, we have updated the outdated references (#18 and #43) with the relevant literature to ensure the timeliness and reliability of the cited evidence. All revisions have been completed in the revised manuscript, and we appreciate your guidance in enhancing the compliance and rigor of the paper.

4. Response to Comments on the Quality of English Language

Point 1: Moderate language editing is required throughout the manuscript.

Response 1: 

Thank you for your language comment. We have completed moderate language editing of the whole manuscript for improved accuracy and fluency, with all revisions highlighted in the revised version.

5. Additional clarifications

All relevant information has been addressed in the preceding responses, so no additional clarifications are needed.

Response to Reviewer 3 Comments

1. Summary

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files. [This is only a recommended summary. Please feel free to adjust it. We do suggest maintaining a neutral tone and thanking the reviewers for their contribution although the comments may be negative or off-target. If you disagree with the reviewer's comments please include any concerns you may have in the letter to the Academic Editor.]

2. Questions for General Evaluation

Reviewer’s Evaluation

Response and Revisions

Does the introduction provide sufficient background and include all relevant references?

Please refer to our detailed response in the Point-by-Point Response Letter below.

Are all the cited references relevant to the research?

Is the research design appropriate?

Are the methods adequately described?

Are the results clearly presented?

Are the conclusions supported by the results?

3. Point-by-point response to Comments and Suggestions for Authors

Comments 1: Please delete the following paragraph in the beginning of the introduction section.

The introduction should briefly place the study in a broad context and highlight why 55 it is important. It should define the purpose of the work and its significance. The current 56 state of the research field should be carefully reviewed and key publications cited. Please 57 highlight controversial and diverging hypotheses when necessary. Finally, briefly men- 58 tion the main aim of the work and highlight the principal conclusions. As far as possible, 59 please keep the introduction comprehensible to scientists outside your particular field of 60 research. References should be numbered in order of appearance and indicated by a nu- 61 meral or numerals in square brackets—e.g., [1] or [2,3], or [4–6].

Response 1:

Thank you for your comment. We agree with this suggestion and have deleted the specified paragraph at the beginning of the introduction section in the revised manuscript. The relevant revision has been completed and the content of the introduction section has been adjusted accordingly.

Comments 2: The selection criteria was very clear presented. Also, methods were very clear presented. They determine biochemicals parameters. Please indicate the provenience of the reagents used. Did the authors determine insuline resitance for the children included in the study?

Response 2:

Thank you for your positive feedback on the clarity of our study’s selection criteria and methods, as well as your valuable questions. Regarding the provenance of the reagents used for biochemical parameter detection, we have supplemented this information in the manuscript: all biochemical analyses were performed using reagents from Roche Diagnostics. This revision is located at Line 172 of the "2.2.5. Laboratory Measurements" section (highlighted in red). Besides, we measured the participants’ insulin levels and fasting plasma glucose (FPG) as part of the biochemical analyses. We appreciate your careful review and constructive comments, which have helped improve the completeness of our manuscript.

Comments 3: Did the authors use a standardized questionnaire?

Response 3:

Response:

Thank you for your question. A standardized structured questionnaire was used in this study for data collection. This questionnaire was designed and developed by experienced physicians and researchers, and it was used to collect information on participants' dietary habits, physical activity, sleep status and other relevant variables. Specifically, dietary intake was assessed via a food frequency retrospective method, and all information in the questionnaire was obtained through self-report by participants and their guardians. Notably, the questionnaire was only distributed to participants who had signed the informed consent form, ensuring the compliance of the research process.

Comments 4: Please present the results for biochemical parameters.

Response 4:

Thank you for your valuable comment. We have supplemented the results of key biochemical parameters, including high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), alanine aminotransferase (ALT), and fasting plasma glucose (FPG), in Table 2 of the revised manuscript. All additions have been completed in accordance with the study’s laboratory measurement methods and statistical reporting standards, and we appreciate your guidance in enhancing the comprehensiveness of the results section.

Comments 5: Could the authors said something about the degree of steatosis? Maybe they could analyzed the results function the degree of steatosis.

Response 5:

Thank you for this insightful suggestion. We fully agree that analyzing the association between the degree of hepatic steatosis and bone mineral density would further enrich the findings of this study. However, due to the limitations of the clinical examination protocol in our current population-based cohort (the screening only involved a binary assessment of "presence or absence of hepatic steatosis" without grading its severity), we did not collect data on the degree of hepatic steatosis.

We plan to incorporate the assessment of steatosis severity in our future cohort studies to explore this potential association in depth.

Again, we appreciate your valuable input, which has provided clear guidance for the direction of our subsequent research.

4. Response to Comments on the Quality of English Language

Point 1: The English is fine and does not require any improvement.

Response 1:

Thank you for your positive comment on the manuscript's English language. We have also made appropriate language revisions to the manuscript by incorporating comments from other reviewers, and all these revisions have been highlighted in red in the revised version.

5. Additional clarifications

All relevant information has been addressed in the preceding responses, so no additional clarifications are needed.

Response to Reviewer 4 Comments

1. Summary

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.

2. Questions for General Evaluation

Reviewer’s Evaluation

Response and Revisions

Does the introduction provide sufficient background and include all relevant references?

Can be improved

Please refer to our detailed response in the Point-by-Point Response Letter below.

Are all the cited references relevant to the research?

Is the research design appropriate?

Can be improved

Are the methods adequately described?

Can be improved

Are the results clearly presented?

Can be improved

Are the conclusions supported by the results?

Yes

Are all figures and tables clear and well-presented?

Yes

3. Point-by-point response to Comments and Suggestions for Authors

Comments 1: Improve the wording of the study objective.

Response 1:

Thank you very much for your suggestion. We have revised the wording of the study objective as advised, and the revised content is highlighted in red at Lines 15–17 of the revised manuscript for your reference.

Comments 2: In the introduction, it is important that the authors briefly address the importance of diet in the prevention and management of MAFLD. In the case of children and adolescents, it is essential to reduce the intake of added fructose and to avoid alcohol consumption. PMID: 39270816

Response 2:

Thank you for your valuable suggestion regarding the Introduction section. We have added the relevant discussion on the importance of dietary intervention in the prevention and management of MAFLD, and specifically emphasized the necessity of reducing added fructose intake and avoiding alcohol consumption in children and adolescents in the revised manuscript (Lines 85–87). Your guidance has greatly enriched the research background of this paper and made the content of the Introduction more comprehensive.

Comments 3: Regarding the methodology and results, is it possible to conduct a more in-depth analysis of the diet? For example, the intake of dairy products (a dietary source of calcium and high-biological-value proteins), and unhealthy foods? I believe a more specific nutritional analysis would greatly benefit the study, considering the intake of key nutrients for the growth and development of bone mineral mass.

Response 3:

Thank you for your insightful suggestion. We fully agree that in-depth analysis of dietary factors would add substantial value to the study, as diet plays a critical role in both MAFLD pathogenesis and bone mineral accrual in children.

In our study, we did collect basic dietary information through questionnaires (e.g., dietary frequency of fish, eggs, milk, vegetables, meat, fried foods, and sugar-sweetened beverages, as presented in Table 3 of the manuscript). However, due to the following considerations, we have not conducted further in-depth nutritional analysis in the current work: First, the dietary data were collected as frequency variables (e.g., "≥1 time per day" or "≥1 time per week") rather than quantitative assessments (e.g., gram-level intake of calcium or protein), which limits the precision of evaluating the specific effects of individual nutrients or food groups. Second, the core objective of this study was to clarify the independent association between MAFLD and bone mineral density in school-aged children using propensity score matching to control for confounding factors such as age, sex, and pubertal stage. Adding extensive dietary analysis would expand the scope of the current research and potentially divert attention from the primary research question.

We acknowledge that the lack of in-depth dietary analysis is a limitation of this study, and we have supplemented this point in the "Strengths and Limitations" section of the revised manuscript. As suggested, exploring the interactive effects of diet, MAFLD, and bone health is indeed a crucial direction for future research. We plan to design subsequent prospective cohort studies that incorporate validated dietary assessment tools (e.g., 24-hour dietary recalls or food frequency questionnaires with quantitative calibration) to accurately measure nutrient intake. This will enable us to systematically analyze how specific dietary factors mediate or modify the association between MAFLD and bone mineral density, and provide more targeted dietary intervention strategies for pediatric MAFLD patients at risk of bone loss.

Thank you again for pointing out this important research gap, which has helped us identify clear directions for future work.

Comments 4: Regarding the discussion, I suggest improving the aspects related to diet, nutrient absorption, and the role of the liver. These points should focus on how hepatic steatosis can alter the metabolism of nutrients relevant to bone mineralization. For example, hepatic steatosis and vitamin D synthesis.

Response 4:

Thank you for your valuable suggestion. We have revised the Discussion section to enhance the content related to diet, nutrient absorption, and the liver’s role—specifically focusing on how hepatic steatosis alters the metabolism of bone-mineralization relevant nutrients. All revisions are highlighted in red in the manuscript (Lines 350-359).

Comments 5: What nutritional and clinical implications would this study have?

Response 5:

Thank you for this valuable comment. Inspired by your suggestion, we have reviewed relevant literature and will add dedicated content on nutritional and clinical implications in the "Discussion" section to enhance the study’s practical value.

Nutritional Implications:

1.    Restrict added fructose (from sugar-sweetened beverages, processed snacks) and eliminate alcohol to control MAFLD progression.

2.    Optimize intake of calcium (dairy, leafy greens) and vitamin D (fatty fish, egg yolks) to mitigate BMD loss.

3.    Balance energy and protein intake (lean meat, fish, legumes) to support muscle and bone strength, especially for overweight/obese children with MAFLD.

Clinical Implications:

1.    Integrate BMD screening (quantitative ultrasound) into routine care for pediatric MAFLD patients, particularly boys, 12–14-year-olds, and those in mid-to-late puberty.

2.    Promote multidisciplinary interventions combining weight-bearing physical activity, personalized nutritional counseling, and metabolic monitoring.

3.    Enhance awareness among clinicians and caregivers about the coexistence of MAFLD and low BMD for early intervention.

We greatly appreciate your guidance in strengthening the manuscript’s relevance and impact.

4. Response to Comments on the Quality of English Language

Point 1: The English is fine and does not require any improvement.

Response 1:

Thank you for your positive comment on the manuscript's English language. We have also made appropriate language revisions to the manuscript by incorporating comments from other reviewers, and all these revisions have been highlighted in red in the revised version.

5. Additional clarifications

All relevant information has been addressed in the preceding responses, so no additional clarifications are needed.