Assessing Gender and Age Differences in the Adoption of Sustainable Diets: Insights from an Intervention of the Mediterranean Diet

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

(1) At L74, the mention of the "IRCCS San Raffaele ethics committee (registration number RP 23/13)" requires a citation or link for verification.

(2) The first three paragraphs of the introduction are overly concise and fail to adequately explain the background of the study, as well as the broader research progress and gaps. This insufficient transition does not effectively lead into the research presented in this paper.

(3) The questionnaire survey method is one of the core research approaches in this paper. During the introduction of this design in Sections 2.1 and 2.2, the selection of participants appears arbitrary and lacks rigor. There are scientific and standardized methods that can be referenced for such a design. It is recommended to verify the basis and scientific validity of these questionnaires.

(4) What is the design basis for Section 2.4 "Dietary Intervention"? Are there citations for the numerous data presented? Is there a rigorous foundation for these data?

(5) The section title in 2.6 "Sustainability" is incomplete. Please provide a full section title. Additionally, the formula for the sustainability index lacks a citation for its source.

(6) It is suggested that a bar chart or pie chart would be more appropriate for Figure 1.

(7) It is recommended to revise the expression throughout the text. Gender differences should only be discussed academically and do not imply superiority or inferiority between men and women. Furthermore, the Mediterranean diet is globally recognized as a healthy eating pattern, but it has its own strengths and weaknesses when compared to other renowned dietary patterns. The narrative should not overwhelmingly praise the Mediterranean diet while ignoring the actual applicable populations and geographical differences.

Author Response

Dear Reviewer,

First of all, I would like to thank you for the valuable impulses that allowed me to improve the quality of the manuscript. All changes made are highlighted by yellow color, in the revised version of the manuscript, to facilitate the review process. Hoping that I have satisfied your requests as much as possible, I kindly ask you to re-evaluate our paper. 

The Author

 

Reviewer #1

(1) At L74, the mention of the "IRCCS San Raffaele ethics committee (registration number RP 23/13)" requires a citation or link for verification.

I appreciate the reviewer’s request for verification. The study was approved by the IRCCS San Raffaele ethics committee (registration number RP 23/13, approval date: 5 May 2023). To facilitate verification, the ethics approval document is publicly accessible at the following link: https://drive.google.com/file/d/1KO1qPtveE7B2nTK12_b8Y8qrUzOrXKfL/view?usp=sharing 

(2) The first three paragraphs of the introduction are overly concise and fail to adequately explain the background of the study, as well as the broader research progress and gaps. This insufficient transition does not effectively lead into the research presented in this paper.

I appreciate the reviewer's constructive feedback regarding the introduction. In response to this concern, I have expanded the first three paragraphs of the introduction to provide a more complete background on the topic of the study. The revised text now includes a broader discussion of the impact of gender and age on sustainable food choices, incorporating references to reviews and key findings from previous research on food transitions. In addition, I reinforced the discussion of research gaps by highlighting the limited availability of studies assessing the effectiveness of dietary interventions in changing sustainable eating behaviours, particularly within the context of the Mediterranean diet. 

(3) The questionnaire survey method is one of the core research approaches in this paper. During the introduction of this design in Sections 2.1 and 2.2, the selection of participants appears arbitrary and lacks rigor. There are scientific and standardized methods that can be referenced for such a design. It is recommended to verify the basis and scientific validity of these questionnaires.

I appreciate the reviewer's critical remarks regarding the selection of participants and the scientific validity of the questionnaire. To address these concerns, I have revised sections 2.1 and 2.2 to make explicit reference to established scientific methods and standardised approaches used in dietary research. The revised text clarifies that participant selection followed structured epidemiological protocols observed in previous studies. Furthermore, I reinforced the discussion on the scientific basis of the questionnaire by linking its structure to validated diet assessment tools, including the research of Carbonneau et al. (2017) and Bailey et al. (2021). Although the questionnaire itself has not been independently validated as a stand-alone instrument, its structure aligns with established methodologies widely used in food preference and food intake research.

(4) What is the design basis for Section 2.4 "Dietary Intervention"? Are there citations for the numerous data presented? Is there a rigorous foundation for these data?

I appreciate the reviewer’s request for additional scientific support regarding the dietary intervention. To address this concern, I have revised Section 2.4 - Dietary Intervention, incorporating key references that validate the MedDiet as a scientifically established approach for weight management and metabolic health. The Mediterranean diet model adopted in this study aligns with findings from Dominguez et al. (2023), which highlight its inverse association with obesity and chronic diseases related to metabolic dysfunction. The protective role of olive oil and polyphenols in reducing cardiovascular disease risk by 35% has been substantiated in previous analyses (Tapsell, 2014). The dietary structure and macronutrient distribution were determined based on prior Mediterranean diet trials and computed using Winfood 2.8 software, a validated nutritional tool.

 

(5) The section title in 2.6 "Sustainability" is incomplete. Please provide a full section title. Additionally, the formula for the sustainability index lacks a citation for its source.

I thank the reviewer for the suggestion. The title of Section 2.6 has been updated to make it more complete. In addition, it has been clarified that the sustainability index used in the study was developed from established methodologies in the literature, with reference to models already used for assessing food sustainability. The method of calculating the index was described in more detail to highlight the criteria used in its construction and its consistency with previous approaches. These changes have been incorporated into the manuscript to ensure greater methodological clarity.

(6) It is suggested that a bar chart or pie chart would be more appropriate for Figure 1.

I appreciate the reviewer’s suggestion regarding Figure 1. To improve clarity and facilitate comparison, I have replaced the original heatmap with a radar chart. This format enhances the visualization of gender differences in food consumption while also highlighting sustainable and non-sustainable foods. Statistical significance has been assessed and included in the figure caption to ensure a robust interpretation of the results. The updated figure has been incorporated into the revised manuscript.

(7) It is recommended to revise the expression throughout the text. Gender differences should only be discussed academically and do not imply superiority or inferiority between men and women. Furthermore, the Mediterranean diet is globally recognized as a healthy eating pattern, but it has its own strengths and weaknesses when compared to other renowned dietary patterns. The narrative should not overwhelmingly praise the Mediterranean diet while ignoring the actual applicable populations and geographical differences.

I appreciate the reviewer's observation regarding the framing of gender differences and the discussion of the Mediterranean diet. I have revised the manuscript to ensure that gender differences are discussed objectively without implying superiority or inferiority. In addition, I refined the discussion of the Mediterranean diet, recognising its strengths and limitations compared to other dietary models. I have also clarified that the results refer to an Italian cohort and may not be directly generalisable to other populations. These changes are reflected in the revised text.

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Author, 

 

Please, find below a few suggestions of improvement of your manuscript:

• The Introduction section is very short so I would highly recommend improving it with more references, maybe it would be useful to place the case study in a context, namely, how it applies to Italy the sustainable Mediter. diet. Also, it would be useful to emphasize more the gap in the literature and make connections with the existing literature , especially Italian case studies;
• Although the questionnaire for the assessment of food preference was not formally validated (line 83), and the author included this as a limitation, it is highly advisable to declare at least a Cronbach alpha higher than 0,70. This is highly necessary, otherwise the research results unfortunately are doubtful. 
• figure 2 caption is in Italian
• I believe in the Materials and methods section you should add a paragraph stating how you decided to use the Mann-Whitney U test and the t-tests, namely based on a Normality test- KS or Shapiro Wilk. This will be more clear. 
• The Discussion section should be improved in a Further directions subsection. It would be useful to answer the questions who can use the results and how the results can be used. 
• The conclusion section should be improved with the major findings of the study. 

Thank you!

 

Good luck!

Author Response

Dear Reviewer,

First of all, I would like to thank you for the valuable impulses that allowed me to improve the quality of the manuscript. All changes made are highlighted by yellow color, in the revised version of the manuscript, to facilitate the review process. Hoping that I have satisfied your requests as much as possible, I kindly ask you to re-evaluate our paper. 

The Author

 

Reviewer #2

The Introduction section is very short so I would highly recommend improving it with more references, maybe it would be useful to place the case study in a context, namely, how it applies to Italy the sustainable Mediter. diet. Also, it would be useful to emphasize more the gap in the literature and make connections with the existing literature , especially Italian case studies;

Thank you for your valuable comments on the introduction of my manuscript. I have expanded this section to better contextualise the study in the Italian landscape and to highlight gaps in the existing literature. In particular, I have included recent data showing a significant decrease in the adherence to the Mediterranean Diet among the Italian population, discussing the main barriers that hinder the adoption of this diet, such as the high cost of fresh food and the lack of time to prepare meals. Furthermore, I highlighted how gender and age differences influence adherence to the Mediterranean Diet, with women and young people tending to follow this dietary pattern more closely. These additions aim to provide a more complete picture of the Italian context, emphasising the importance of considering socio-demographic factors in the adoption of sustainable diets. I hope these changes adequately address your comments and help strengthen the manuscript.

Although the questionnaire for the assessment of food preference was not formally validated (line 83), and the author included this as a limitation, it is highly advisable to declare at least a Cronbach alpha higher than 0,70. This is highly necessary, otherwise the research results unfortunately are doubtful. 

I appreciate the reviewer’s suggestion to report Cronbach’s alpha for the food preference questionnaire. Internal consistency was assessed by calculating Cronbach’s alpha, which measures the correlation between responses across food preference items. The final Cronbach’s alpha was 0.74, indicating acceptable reliability. This methodological detail has been included in the Methods section for transparency.

figure 2 caption is in Italian

Thank you. I have translated the part I mistakenly left in Italian.

I believe in the Materials and methods section you should add a paragraph stating how you decided to use the Mann-Whitney U test and the t-tests, namely based on a Normality test- KS or Shapiro Wilk. This will be more clear. 

I appreciate the reviewer's suggestion to clarify the statistical approach used in this study. I have now explicitly stated in the Methods section that normality was assessed using the Shapiro-Wilk test, given the sample size. Accordingly, variables with normal distribution were analysed using t-tests, while variables with non-normal distribution were assessed using the Mann-Whitney U-test. For pairwise comparisons, the Wilcoxon signed-rank test was applied when normality was not satisfied. These details were included to improve the clarity and rigour of the statistical analysis.

The Discussion section should be improved in a Further directions subsection. It would be useful to answer the questions who can use the results and how the results can be used. 

I appreciate the reviewer's suggestion to improve the Discussion section by adding a ‘Further Directions’ subsection. For this reason, I have included a dedicated paragraph to introduce Table 2, which summarises the main results and their potential applications. This addition clarifies how the results can be used by nutritionists, public health professionals, policy makers and researchers to develop targeted interventions, promote sustainable food choices and refine dietary recommendations.

The conclusion section should be improved with the major findings of the study. 

I appreciate the reviewer's suggestion to enrich the Conclusions section. In response, I have expanded this section by providing a more detailed summary of the main findings of the study, specifically highlighting gender and age differences in dietary sustainability, the decrease in the sustainability index after the intervention, and the role of cultural and behavioural factors in dietary transitions. Furthermore, I emphasised the importance of demographic-specific nutritional interventions to improve adherence to sustainable diets.

Reviewer 3 Report

Comments and Suggestions for Authors

The topic you have developed is interesting but some implementations are needed to strengthen the scientific soundness of the manuscript. In the introduction, it would possibly be useful to include reviews on the topic in the literature. In the research design, the hypothesis part is weak and research questions need to be formulated. 

In section 2.1 specify the methodology used, which has been used in other scientific research. Although inclusion and exclusion criteria have been included more details must be given on recruitment. Which sample population was contacted and then which one actually participated (1666) in the survey and the reasons for exclusion. The participants have a significant on the presumably Italian population. Data is available on the nationality of the survey participants. Another critical point is in section 2.2. it is mentioned that the questions have been validated by other scientific studies. It is necessary to correlate the question with the research. Consider inserting a figure that would visually illustrate the research design with all other components in the comments.

In paragraph 3 the results should be correlated with the research questions and then the most significant ones presented in the following discussion paragraph. Caution from line 220-224 the text has not been translated into English.

The conclusions are too succinct and should be enriched

 

Comments on the Quality of English Language

I am not qualified to judge English

Author Response

Dear Reviewer,

First of all, I would like to thank you for the valuable impulses that allowed me to improve the quality of the manuscript. All changes made are highlighted by yellow color, in the revised version of the manuscript, to facilitate the review process. Hoping that I have satisfied your requests as much as possible, I kindly ask you to re-evaluate our paper. 

The Author

 

Reviewer #3

The topic you have developed is interesting but some implementations are needed to strengthen the scientific soundness of the manuscript. 

In the introduction, it would possibly be useful to include reviews on the topic in the literature. In the research design, the hypothesis part is weak and research questions need to be formulated. 

​​I appreciate the reviewer's insightful comments. In response, I have revised the introduction to include relevant literature reviews that provide broader context on gender and age differences in sustainable food choices. In particular, I have included references to the systematic reviews by Modlinska et al. (2020) and Alcorta et al. (2021), which explore gender attitudes towards plant-based diets and cultural barriers to the adoption of sustainable foods. In addition, I highlighted the gap in research on the effectiveness of dietary interventions in changing these patterns, particularly within the Mediterranean diet. These additions strengthen the theoretical background of the study and justify the need for this investigation. To address concerns about the research design, I strengthened the hypothesis section and formulated explicit research questions. 

In section 2.1 specify the methodology used, which has been used in other scientific research. Although inclusion and exclusion criteria have been included more details must be given on recruitment. Which sample population was contacted and then which one actually participated (1666) in the survey and the reasons for exclusion. The participants have a significant on the presumably Italian population. Data is available on the nationality of the survey participants. Another critical point is in section 2.2. it is mentioned that the questions have been validated by other scientific studies. It is necessary to correlate the question with the research. 

I appreciate the reviewer's valuable feedback. In response, I expanded section 2.1 to clarify the methodological framework, aligning it with previous research. The revised section now provides a detailed description of the recruitment process, specifying that an initial sample of 1800 people was contacted and screened, leading to a final sample of 1666 participants after excluding 134 cases due to incomplete data or inconsistencies in calorie intake. I also addressed the problem of the representativeness of the sample. Although the study population consisted entirely of Italian residents who completed the questionnaire in Italian, data on nationality were not explicitly collected. However, this demographic detail was included in the revised text to clarify the relevance of the study in the Italian food context. In section 2.2, I further clarified that the questionnaire used in this study was structured following validated formats previously applied in research on food preferences and eating habits. 

Consider inserting a figure that would visually illustrate the research design with all other components in the comments.

I appreciate the reviewer's suggestion to include a figure that visually represents the study design. In response, I have added a figure, which provides a structured flow chart illustrating the entire research process. This figure illustrates the recruitment of participants, eligibility screening, data collection at baseline and after the intervention, the two-month Mediterranean diet intervention.. It also illustrates the exclusion criteria and emphasises the use of food diaries and sustainability indices as primary assessment tools.

In paragraph 3 the results should be correlated with the research questions and then the most significant ones presented in the following discussion paragraph. 

I appreciate the reviewer's suggestion to better correlate the results with the research questions and to highlight the most significant findings before discussion. I have revised paragraph 3 to explicitly link key findings to the objectives of the study, clarifying how gender and age influence adherence to sustainable food choices. Furthermore, I made sure that the most relevant findings, such as the impact of meat consumption on the sustainability index, age-related differences in dietary transitions and cultural barriers to certain sustainable foods, were clearly presented. 

Caution from line 220-224 the text has not been translated into English.

Thank you. I have translated the part I mistakenly left in Italian.

The conclusions are too succinct and should be enriched

I appreciate the reviewer's suggestion to enrich the Conclusions section. In response, I have expanded this section by providing a more detailed summary of the main findings of the study, specifically highlighting gender and age differences in dietary sustainability, the decrease in the sustainability index after the intervention, and the role of cultural and behavioural factors in dietary transitions. Furthermore, I emphasised the importance of demographic-specific nutritional interventions to improve adherence to sustainable diets.

 

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The Author improved the manuscript consistently. 

 

No further suggestions!

Comments on the Quality of English Language

The English language is clear. 

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,

I appreciated the in-depth review process of the entire article, which made it possible to strengthen the scientific soundness of the manuscript. Based on my point of view, I therefore believe that your article is eligible for publication.