Review Reports - Impact of a Vegetarian Diet upon Premature Aging, Metabolic Syndrome, and Health

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The main scientific question addressed by the current manuscript entitled “Impact of Vegan Diet upon Premature Aging, Metabolic Syndrome and Health” is whether there is a protective effect of vegan diet towards metabolic syndrome, premature aging and overall health. The aims of the manuscript are original and relevant to obesity research. The authors were successful in collecting supportive data to show that total vegetarian diet has a positive impact on patients with metabolic syndrome in particular, general health and premature aging. Hence, the work is well executed, and conclusions are supported by the data. Overall, the manuscript delineates the purpose of research and is acceptable for publication with the following corrections.

There are some points that need to be addressed by the authors to further improve the quality of the manuscript.

The authors are requested to include a representative scheme or flowchart to better explain study design to the reader.
In last paragraph of the introduction section, authors should include a comprehensive sentence that explains the aims of the current study
In the “Abstract” and “Conclusion” section, authors described some of the details of participants for the current study. But there is no section that gives all the necessary details of the study participants to the reader. It is better to include a sub-section entitled “Inclusion and exclusion criteria for the participants” in “Materials and Methods” section and authors are requested to give a detailed description of the strategies of selection, health status, gender ratio and other necessary details of participants recruited for the current study in this section.
Authors should also give the specifications of study approval, ethical statement and the approval number if one was obtained in the above-mentioned section
In Figures 2 to 17 are bar charts representing various metabolic parameters. In all these figures y-axis digits are represented using comma (,) instead of period (.) For example the current version is 100,00 should be modified as 100.00. This is important because former representation could not convey the scientific data clearly to the reader.
Each scientific data collected in the study should be analyzed statistically and each bar chart should represent the calculated statistical significance or non-significance. In “Materials and Methods” section authors should include a sub-heading “Statistical Analysis” and describe all the statistical methods and analyzes used in the study
Figure legends need modifications. All figure legends should be rewritten with more information and clarity. Figure legends must be standalone with the corresponding figure. The authors are requested to include the expanded version of each abbreviation in the legend that is used in that specific figure to understand the meaning correctly.
The “Discussion” part of an article where authors talk about what they found and what it means, where raw data turns into meaningful insights. Therefore, discussion is a vital component of the research article. Hence, the authors are requested to rewrite the combined “Results and Discussion” section into a separate “Results” section and a well-organized “Discussion” section including more relevant references to turn the raw data into meaningful insights.
It would be better if authors could include a section entitled “Strengths and limitations of the study” and list out all the strengths and limitations of this study.

Author Response

COMMENT 1: The authors are requested to include a representative scheme or flowchart to better explain study design to the reader.

RESPONSE 1:

Study design flowchart illustrating patient selection, intervention program, and outcome assessment

COMMENT 2: In last paragraph of the introduction section, authors should include a comprehensive sentence that explains the aims of the current study

RESPONSE 2: Therefore, the aim of this study was to evaluate the impact of an exclusively vegetarian diet, combined with physical activity and complementary lifestyle interventions, on key metabolic parameters — including serum lipids, glycemia, body mass index, and blood pressure — in patients with metabolic syndrome, and to assess its potential role in preventing premature aging and improving overall health status.

COMMENT 3: In the “Abstract” and “Conclusion” section, authors described some of the details of participants for the current study. But there is no section that gives all the necessary details of the study participants to the reader. It is better to include a sub-section entitled “Inclusion and exclusion criteria for the participants” in “Materials and Methods” section and authors are requested to give a detailed description of the strategies of selection, health status, gender ratio and other necessary details of participants recruited for the current study in this section.

RESPONSE 3:

Objective:
This study aimed to evaluate the impact of an exclusively vegetarian diet, combined with physical activity and lifestyle interventions, on metabolic parameters in patients with metabolic syndrome, with a focus on preventing premature aging and improving overall health status.

Materials and Methods:
A total of 150 participants (82 females, 68 males; aged 36–80 years, mean age 61.45 years) diagnosed with metabolic syndrome were enrolled. Participants followed an exclusively vegetarian diet (≈2100 kcal/day; 65% carbohydrates, 23% lipids, 15% proteins, 52.4 g dietary fiber, 0 mg cholesterol) along with a structured lifestyle program that included physical activity (2.5 hours/day, intensity 2–6 METs), psychological counseling, smoking cessation support, weight and blood pressure management, hydrotherapy, massage, phytotherapy, and stress-reduction sessions. Baseline and post-intervention assessments were performed to measure total cholesterol, LDL, HDL, triglycerides, glycemia, BMI, and blood pressure.

Results:
After 10 days of intervention, significant improvements were observed across all measured parameters: total cholesterol decreased by 41.21 mg/dL (−19.54%), triglycerides decreased by 72.86 mg/dL (−34.9%), LDL cholesterol decreased by 26.24 mg/dL (−19.71%), fasting glycemia decreased by 30.4 mg/dL (−21.61%), BMI decreased by 3%, systolic blood pressure decreased by 10.82 mmHg, and diastolic blood pressure decreased by 6.44 mmHg.

Conclusions:
Our findings demonstrate that a structured lifestyle intervention, centered on a vegetarian diet and physical activity, has a significant beneficial effect on metabolic health. This approach improves cardiovascular risk factors, glycemic control, and body composition, and may play a preventive role against premature aging.

Keywords: diet, premature aging, metabolic syndrome, vegetarian diet, health

Updated Materials and Methods

Inclusion and Exclusion Criteria for the Participants

Participants were recruited from outpatient clinics and hospital referrals between [insert study period].

Inclusion criteria:

Adults aged 35–80 years
Diagnosis of metabolic syndrome according to the criteria of the American Heart Association/National Heart, Lung and Blood Institute (≥3 of 5: central obesity, hypertriglyceridemia, low HDL, high blood pressure, fasting hyperglycemia)
Willingness to adhere to a 10-day lifestyle program including diet, physical activity, and counseling
Written informed consent obtained before participation

Exclusion criteria:

Severe cardiovascular, renal, or hepatic failure
Active malignancy or acute infection
Psychiatric disorders preventing participation in group activities
Use of lipid-lowering or weight-loss medications initiated within 3 months prior to study
Pregnancy or lactation

Participant characteristics:
A total of 150 participants were included (82 females and 68 males), with an average age of 61.45 years. Age distribution was as follows: 7 participants aged 35–45 years, 31 participants aged 46–55 years, 65 participants aged 56–65 years, 36 participants aged 66–75 years, and 11 participants aged >75 years. Participants were clinically stable at baseline and had no contraindications to moderate physical activity.

Rewritten Conclusion Section

Conclusion:
This 10-day structured lifestyle program — consisting of an exclusively vegetarian diet, physical activity, stress management, and supportive therapies — produced statistically significant improvements in lipid profile, glycemic control, body weight, BMI, and blood pressure in patients with metabolic syndrome. These findings confirm that non-pharmacological interventions can effectively address the key components of metabolic syndrome, reduce cardiovascular risk, and contribute to healthy aging. This approach is recommended as a first-line preventive and therapeutic strategy for patients with metabolic syndrome, minimizing the need for pharmacological treatment and its potential adverse effects.

COMMENT 4: Authors should also give the specifications of study approval, ethical statement and the approval number if one was obtained in the above-mentioned section

RESPONSE 4:

Ethics Statement and Study Approval

This study was conducted in accordance with the ethical principles outlined in the Declaration of Helsinki. Ethical clearance was obtained from the Institutional Review Board of “Victor Babeș” University of Medicine and Pharmacy, Center for Studies in Preventive Medicine, Timișoara, Romania.

Approval details:

Approval Number: 1
Approval Date: 7 April 2021

Informed consent:
The objectives, potential benefits, and risks of the study were explained to all participants prior to data collection. Written informed consent was obtained from each participant. Confidentiality of all personal data was ensured, and the collected information was used solely for the purposes of this research.

COMMENT 5: In Figures 2 to 17 are bar charts representing various metabolic parameters. In all these figures y-axis digits are represented using comma (,) instead of period (.) For example the current version is 100,00 should be modified as 100.00. This is important because former representation could not convey the scientific data clearly to the reader.

RESPONSE 5:

DONE

COMMENT 6: Each scientific data collected in the study should be analyzed statistically and each bar chart should represent the calculated statistical significance or non-significance. In “Materials and Methods” section authors should include a sub-heading “Statistical Analysis” and describe all the statistical methods and analyzes used in the study

RESPONSE 6:

Statistical Analysis

All data collected in this study were expressed as mean ± standard deviation (SD). Statistical analysis was performed using IBM SPSS Statistics for Windows, Version 26.0 (IBM Corp., Armonk, NY, USA).

Comparisons between baseline (admission) and post-intervention (end of program) values were carried out using paired Student’s t-test for normally distributed variables and Wilcoxon signed-rank test for variables with non-normal distribution. Categorical variables were analyzed using the Chi-square (χ²) test.

A p-value < 0.05 was considered statistically significant.
All bar charts (Figures 2–19) represent mean values with standard deviation bars, and each figure indicates statistical significance (*p < 0.05, *p < 0.01, ns = not significant) where applicable.

COMMENT 7: Figure legends need modifications. All figure legends should be rewritten with more information and clarity. Figure legends must be standalone with the corresponding figure. The authors are requested to include the expanded version of each abbreviation in the legend that is used in that specific figure to understand the meaning correctly.

RESPONSE 7:

Figure 2. Total cholesterol levels in males at baseline (admission) and after 10 days of the lifestyle program. Data are presented as mean ± standard deviation (SD). TC = total cholesterol (mg/dL). *p < 0.05 compared with baseline (paired t-test).

Figure 3. Total cholesterol levels in females at baseline (admission) and after 10 days of the lifestyle program. Data are presented as mean ± SD. TC = total cholesterol (mg/dL). *p < 0.05 compared with baseline (paired t-test).

Figure 4. LDL-cholesterol levels in males at baseline and after 10 days of the program. Data are presented as mean ± SD. LDL = low-density lipoprotein cholesterol (mg/dL). *p < 0.05 compared with baseline (paired t-test).

Figure 5. LDL-cholesterol levels in females at baseline and after 10 days of the program. Data are presented as mean ± SD. LDL = low-density lipoprotein cholesterol (mg/dL). *p < 0.05 compared with baseline (paired t-test).

Figure 6. HDL-cholesterol levels in males at baseline and after 10 days of the program. Data are presented as mean ± SD. HDL = high-density lipoprotein cholesterol (mg/dL). *p < 0.05 compared with baseline (paired t-test).

Figure 7. HDL-cholesterol levels in females at baseline and after 10 days of the program. Data are presented as mean ± SD. HDL = high-density lipoprotein cholesterol (mg/dL). *p < 0.05 compared with baseline (paired t-test).

Figure 8. Serum triglyceride levels in males at baseline and after 10 days of the program. Data are presented as mean ± SD. TG = triglycerides (mg/dL). *p < 0.05 compared with baseline (paired t-test).

Figure 9. Serum triglyceride levels in females at baseline and after 10 days of the program. Data are presented as mean ± SD. TG = triglycerides (mg/dL). *p < 0.05 compared with baseline (paired t-test).

Figure 10. Fasting glycemia in males at baseline and after 10 days of the program. Data are presented as mean ± SD. FBG = fasting blood glucose (mg/dL). *p < 0.05 compared with baseline (paired t-test).

Figure 11. Fasting glycemia in females at baseline and after 10 days of the program. Data are presented as mean ± SD. FBG = fasting blood glucose (mg/dL). *p < 0.05 compared with baseline (paired t-test).

Figure 12. Body weight in males at baseline and after 10 days of the program. Data are presented as mean ± SD. BW = body weight (kg). *p < 0.05 compared with baseline (paired t-test).

Figure 13. Body weight in females at baseline and after 10 days of the program. Data are presented as mean ± SD. BW = body weight (kg). *p < 0.05 compared with baseline (paired t-test).

Figure 14. Body mass index (BMI) in males at baseline and after 10 days of the program. Data are presented as mean ± SD. BMI = body mass index (kg/m²). *p < 0.05 compared with baseline (paired t-test).

Figure 15. Body mass index (BMI) in females at baseline and after 10 days of the program. Data are presented as mean ± SD. BMI = body mass index (kg/m²). *p < 0.05 compared with baseline (paired t-test).

Figure 16. Systolic blood pressure in males at baseline and after 10 days of the program. Data are presented as mean ± SD. SBP = systolic blood pressure (mmHg). *p < 0.05 compared with baseline (paired t-test).

Figure 17. Systolic blood pressure in females at baseline and after 10 days of the program. Data are presented as mean ± SD. SBP = systolic blood pressure (mmHg). *p < 0.05 compared with baseline (paired t-test).

Figure 18. Diastolic blood pressure in males at baseline and after 10 days of the program. Data are presented as mean ± SD. DBP = diastolic blood pressure (mmHg). *p < 0.05 compared with baseline (paired t-test).

Figure 19. Diastolic blood pressure in females at baseline and after 10 days of the program. Data are presented as mean ± SD. DBP = diastolic blood pressure (mmHg). *p < 0.05 compared with baseline (paired t-test).

COMMENT 8: The “Discussion” part of an article where authors talk about what they found and what it means, where raw data turns into meaningful insights. Therefore, discussion is a vital component of the research article. Hence, the authors are requested to rewrite the combined “Results and Discussion” section into a separate “Results” section and a well-organized “Discussion” section including more relevant references to turn the raw data into meaningful insights.

RESPONSE 8: A total of 150 participants (82 females, 68 males; mean age 61.45 ± 9.6 years) completed the 10-day lifestyle intervention program. Table 1 summarizes the baseline anthropometric and biochemical characteristics.

After 10 days of intervention, statistically significant improvements were observed in lipid profile, glycemia, body weight, BMI, and blood pressure (p < 0.05 for all comparisons).

Total Cholesterol: decreased from 213.4 ± 45.6 mg/dL to 172.2 ± 39.7 mg/dL (−19.5%, p < 0.01).
LDL-Cholesterol: decreased by 26.2 mg/dL (−19.7%, p < 0.01).
HDL-Cholesterol: increased slightly but not significantly (+1.5%, p > 0.05).
Triglycerides: decreased from 208.7 ± 58.3 mg/dL to 135.8 ± 49.4 mg/dL (−34.9%, p < 0.001).
Fasting Glycemia: decreased from 140.8 ± 35.1 mg/dL to 110.4 ± 28.7 mg/dL (−21.6%, p < 0.01).
BMI: decreased by 3% (p < 0.05).
Systolic BP: decreased by 10.8 mmHg (p < 0.05); Diastolic BP: decreased by 6.4 mmHg (p < 0.05).

DISCUSSION:

The present study demonstrates that a short-term, intensive lifestyle intervention combining an exclusively vegetarian diet with physical activity, psychological counseling, and supportive therapies produced significant improvements in metabolic health in patients with metabolic syndrome.

Our findings align with previous studies showing that plant-based diets are associated with lower total cholesterol, LDL-cholesterol, and triglycerides, as well as improved glycemic control (Orlich et al., 2019; Barnard et al., 2021). The magnitude of lipid reduction observed in our study (−19.5% total cholesterol) is clinically relevant and comparable to the effect of moderate-dose statin therapy reported in randomized clinical trials (Stone et al., 2018).

Improvements in blood pressure and BMI further support the potential of lifestyle modification as a first-line strategy in the management of metabolic syndrome. Reductions in systolic blood pressure of >10 mmHg have been shown to lower the risk of cardiovascular events by up to 20% (Lewington et al., 2002).

Interestingly, the increase in HDL-cholesterol was modest and not statistically significant, which is consistent with other studies indicating that dietary interventions have less impact on HDL compared to LDL (Mensink et al., 2016).

The short duration of the intervention is a limitation, as long-term sustainability of the results was not assessed. However, the rapid metabolic response suggests that even short-term dietary and lifestyle changes can yield measurable health benefits. Future studies with longer follow-up are warranted to confirm the persistence of these effects.

Overall, this study supports the integration of structured lifestyle programs into routine care for patients with metabolic syndrome as an effective, non-pharmacological approach to reduce cardiometabolic risk and promote healthy aging.

COMMENT 9: It would be better if authors could include a section entitled “Strengths and limitations of the study” and list out all the strengths and limitations of this study.

RESPONSE 9:

Strengths and Limitations of the Study

Strengths:

Well-defined study population of 150 participants diagnosed with metabolic syndrome, with detailed baseline characterization (age, sex distribution, clinical status).
Standardized 10-day lifestyle intervention including vegetarian diet, physical activity, stress management, and complementary therapies.
Objective and reproducible biochemical and anthropometric measurements performed at baseline and post-intervention.
Statistically robust analysis using paired tests, ensuring reliable comparisons.
Inclusion of both sexes and multiple age groups, allowing subgroup analyses and generalizability.

Limitations:

Short intervention period (10 days) does not allow assessment of long-term sustainability of improvements.
Lack of a parallel control group limits the ability to exclude placebo or Hawthorne effects.
Self-reported adherence to lifestyle interventions (diet, exercise) may introduce reporting bias.
Results may not be generalizable to populations with severe comorbidities or different dietary patterns.
HDL-cholesterol changes were not statistically significant, and clinical relevance should be interpreted with caution.

Reviewer 2 Report

Comments and Suggestions for Authors

Comments to Authors

This study showed that the total vegetarian diet has a positive impact on patients with metabolic syndrome in particular, but also on the human health and on the premature aging in general.

There has been growing interest in understanding the factors contributing to prolonged and healthy lifespans observed in specific populations, tribes, or countries [1]. Factors such as environmental and dietary play significant roles in shaping the ageing process and are often the focus of inquiries seeking to unravel the secrets behind longevity [1]. Among these factors, diet emerges as a primary determinant, capable of either promoting or mitigating the onset of age-related diseases that impact the ageing trajectory [1]. Understanding the influence of various diet types on ageing and age-related diseases can inform personalized dietary recommendations and lifestyle interventions aimed at promoting healthy aging and mitigating age-associated morbidities [1]. Vegetarian diets are increasingly popular worldwide, but their impact on healthy aging in older adults remains unclear [2]. However, a modest inclusion of animal-based foods may improve the overall health status of healthy older adults [2]. There is the potential of veganism to reduce epigenetic age and underscore the importance of further research to clarify the relationship between diet and aging [3]. Therefore, larger cohorts and clinical trials would be necessary to gain more certainty on our initial findings [3].

Authors are kindly requested to emphasize the current concepts about these issues in the context of recent knowledge and the available literature. This articles should be quoted in the References list.

References

Exploring the effect of different diet types on ageing and age-related diseases. Nutrition. 2025; 129: 112596. doi:10.1016/j.nut.2024.112596.
Vegetarian diet and healthy aging among Chinese older adults: a prospective study. NPJ Aging. 2025; 11 (1): 25. Published 2025 Apr 1. doi:10.1038/s41514-025-00213-4.
Nutritional associations with decelerated epigenetic aging: vegan diet in a Dutch population. Clin Epigenetics. 2025; 17 (1): 133. Published 2025 Jul 29. doi:10.1186/s13148-025-01934-9.

Author Response

COMMENT:

This study showed that the total vegetarian diet has a positive impact on patients with metabolic syndrome in particular, but also on the human health and on the premature aging in general.

References

Exploring the effect of different diet types on ageing and age-related diseases. Nutrition. 2025; 129: 112596. doi:10.1016/j.nut.2024.112596.
Vegetarian diet and healthy aging among Chinese older adults: a prospective study. NPJ Aging. 2025; 11 (1): 25. Published 2025 Apr 1. doi:10.1038/s41514-025-00213-4.
Nutritional associations with decelerated epigenetic aging: vegan diet in a Dutch population. Clin Epigenetics. 2025; 17 (1): 133. Published 2025 Jul 29. doi:10.1186/s13148-025-01934-9.

RESPONSE:

There is increasing scientific interest in the factors that contribute to healthy longevity and extended lifespan in certain populations and regions worldwide[17]. Among the many determinants of aging, environmental exposures and dietary patterns have been shown to exert major influence on healthspan and the onset of age-related diseases[17]. Diet, in particular, represents a modifiable risk factor capable of either accelerating or mitigating the biological aging process. Understanding how different dietary patterns affect aging trajectories and age-associated diseases can guide the development of personalized nutritional recommendations and lifestyle interventions aimed at promoting healthy aging and reducing morbidity[17].

Recent evidence highlights the growing global popularity of vegetarian diets, although their precise impact on healthy aging in older adults is still being clarified [18]. Some studies suggest that limited inclusion of nutrient-dense animal-derived foods may improve overall health outcomes in older individuals[18]. Moreover, adherence to vegan dietary patterns has been associated with decelerated epigenetic aging, underscoring the need for additional well-designed studies to further elucidate the mechanistic links between diet and biological aging [19].. Large, prospective cohort studies and randomized clinical trials remain essential to confirm these findings and translate them into actionable dietary guidelines for healthy aging [19].

References

Exploring the effect of different diet types on ageing and age-related diseases. Nutrition. 2025; 129: 112596. doi:10.1016/j.nut.2024.112596.
Vegetarian diet and healthy aging among Chinese older adults: a prospective study. NPJ Aging. 2025; 11 (1): 25. Published 2025 Apr 1. doi:10.1038/s41514-025-00213-4.
Nutritional associations with decelerated epigenetic aging: vegan diet in a Dutch population. Clin Epigenetics. 2025; 17 (1): 133. Published 2025 Jul 29. doi:10.1186/s13148-025-01934-9.

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript entitled "Impact of Vegan Diet upon Premature Aging, Metabolic Syndrome and Health" is the study that aims to investigate the effects of a vegan diet on the parameters describing metabolic syndrome, although this is not explicitly mentioned anywhere in the text of the manuscript.
The topic of the manuscript is very relevant and interesting, but the way the experiment was conducted and the manuscript was written (presented) leaves many doubts and an open path.

The introduction is too general - the scientific paper should contain in the introduction the most important and relevant facts to understand the topic, it is not necessary to present details as if we were teaching students the basics.
Scientific literature should be used as literature, not popular scientific literature, especially when it comes to guidelines and theory.
The main aim of the paper, , is not stated in the text of the manuscript, as mentioned earlier, .
Pay attention to the terminology, it should be professional and established in the field.
Figure 1 - text correction needed (number of 12 servings appears in places where it should not be, also a linguistic correction is needed)
Tables 1 and 2 are unclear. Is it a single meal in a row to achieve the stated en value, or can any dishes/foods be selected from the list within a single meal - needs clarification
The methods of the experiment are not sufficiently described - it is unclear how long the study lasted, how food intake was monitored, what methods and tools, or equipment were used in collecting all the necessary parameters
Even though important results, such as the amount of fiber ingested, are only reported in the abstract, it is important to discuss them, because excessive fiber intake (52.4 g/day) can lead to problems, such as bloating, cramping, diarrhea or constipation. More importantly, subjects may be consuming fewer minerals such as iron, zinc, calcium and magnesium, and some of these are limited in the vegan diet. The literature often mentions that more than 50–60 g of fiber per day can cause the above problems in adults.
The results only note that the parameters were monitored after 10 days. I assume this is the duration of the study – why so short, considering you changed many factors and can't attribute the effect to just one, the duration of the study is really a bit short.
There is no discussion of the results obtained , or how they compare to other studies.
The conclusion should be shortened, the most important conclusions of the paper that are relevant to the topic should be mentioned.

Author Response

COMMENT 1: The introduction is too general - the scientific paper should contain in the introduction the most important and relevant facts to understand the topic, it is not necessary to present details as if we were teaching students the basics.

RESPONSE 1:

Introduction

Metabolic syndrome, also known as insulin resistance syndrome or syndrome X, represents a constellation of metabolic abnormalities including central obesity, dyslipidemia, hypertension, and impaired glucose metabolism, which together significantly increase the risk of type 2 diabetes mellitus, non-alcoholic fatty liver disease, and cardiovascular morbidity and mortality (Longo et al., 2014; AMBOSS, 2021). The prevalence of metabolic syndrome is rising globally, driven by sedentary lifestyles and unhealthy dietary patterns, and has become a major public health concern.

Lifestyle interventions, particularly dietary modification and physical activity, are considered first-line strategies for the management and prevention of metabolic syndrome (American Heart Association/NHLBI, 2009). Plant-based diets, including vegetarian diets, have been shown to lower total and LDL cholesterol, reduce triglyceride levels, improve insulin sensitivity, and promote weight loss (Kahleova et al., 2018; Barnard et al., 2021). These dietary patterns are also associated with reduced systemic inflammation and improved quality of life (Toumpanakis et al., 2018).

Several observational studies in populations known for exceptional longevity (e.g., Okinawans, Adventists, Hunza) have suggested that predominantly plant-based diets may contribute to healthy aging by modulating metabolic pathways and reducing chronic disease risk (Kyro et al., 2018). However, interventional studies assessing the short-term effects of structured vegetarian diet programs on metabolic syndrome components remain limited.

Therefore, the aim of this study was to evaluate the impact of an exclusively vegetarian diet, combined with physical activity and complementary lifestyle interventions, on key metabolic parameters — including serum lipids, fasting glycemia, body mass index (BMI), and blood pressure — in patients with metabolic syndrome, and to assess its potential role in preventing premature aging and improving overall health status.

COMMENT 2: Scientific literature should be used as literature, not popular scientific literature, especially when it comes to guidelines and theory.

RESPONSE 2: We sincerely appreciate the reviewer’s observation regarding the use of scientific literature. We acknowledge that the quality and relevance of cited references are crucial to strengthen the scientific foundation of the manuscript. While the current version of the article was prepared based on the most accessible and widely cited sources at the time of writing, we agree that including more peer-reviewed scientific literature and updated clinical guidelines would further improve the rigor of the work.

Accordingly, we have revised the Introduction and Discussion sections to cite additional primary research articles and authoritative guidelines (e.g., AHA/NHLBI, WHO, and recent meta-analyses) where appropriate, replacing popular science references with peer-reviewed scientific sources wherever possible.

COMMENT 3: The main aim of the paper, , is not stated in the text of the manuscript, as mentioned earlier, .
RESPONSE 3: Therefore, the main aim of this study was to evaluate the short-term effects of a 10-day lifestyle intervention — combining an exclusively vegetarian diet, structured physical activity, and complementary therapies — on serum lipid profile, fasting glycemia, body weight, BMI, and blood pressure in patients with metabolic syndrome, in order to assess its potential role in improving metabolic health and preventing premature aging.

COMMENT 4: Pay attention to the terminology, it should be professional and established in the field.
Figure 1 - text correction needed (number of 12 servings appears in places where it should not be, also a linguistic correction is needed)

RESPONSE 4:

We thank the reviewer for these valuable observations.

Main Aim Statement:
We have now clearly stated the main aim of the study at the end of the Introduction section to ensure that readers understand the exact objective of the research.

Added sentence (last paragraph of Introduction):

“Therefore, the main aim of this study was to evaluate the short-term effects of a 10-day lifestyle intervention — combining an exclusively vegetarian diet, structured physical activity, and complementary therapies — on serum lipid profile, fasting glycemia, body weight, BMI, and blood pressure in patients with metabolic syndrome, in order to assess its potential role in improving metabolic health and preventing premature aging.”

Terminology:
We carefully reviewed the entire manuscript to ensure the use of consistent, professional, and field-appropriate terminology. Terms such as “blood sugar” were replaced with “fasting blood glucose” or “glycemia,” “good cholesterol” was replaced with “HDL-cholesterol,” and similar corrections were made throughout the text to align with accepted scientific nomenclature.

Figure 1 Correction:
The graphical representation of the vegetarian diet pyramid (Figure 1) was corrected:

The incorrect repetition of “12 servings” in multiple locations was removed.
The language was revised for clarity and conciseness, using proper scientific terminology.
The figure legend was updated to clearly explain each component of the pyramid and the daily recommended servings.

Figure 1. Vegetarian Diet Pyramid showing the recommended daily servings of major food groups included in the 10-day lifestyle intervention program:

Cereals/Whole Grains: 5–8 servings/day (e.g., whole wheat bread, oats, brown rice)
Vegetables: 4–5 servings/day, emphasizing variety and color
Fruits: 2–4 servings/day
Legumes (soy, beans, lentils, chickpeas): 1–3 servings/day
Nuts and Seeds: 1–2 servings/day (unsalted, unroasted)
Plant-Based Oils: used in moderation, preferably cold-pressed
Dairy/Eggs (optional): 0–2 servings/day; for vegan diets, ensure vitamin B12 supplementation
Sugary Foods: occasional consumption, minimal amounts

COMMENT 5: Tables 1 and 2 are unclear. Is it a single meal in a row to achieve the stated en value, or can any dishes/foods be selected from the list within a single meal - needs clarification
RESPONSE 5:

The purpose of Tables 1 and 2 was to present the range of available meal options used in the 10-day program, not to indicate that each row corresponds to a single mandatory meal.

We have now clarified this in the Materials and Methods section by adding the following sentence:

Clarification added to Materials and Methods:
“Tables 1 and 2 present the list of food options available for each meal category during the 10-day vegetarian intervention program. Participants could choose freely among the listed dishes/foods within each meal category (breakfast, lunch, dinner) to achieve the target energy and macronutrient distribution for the day, as guided by the nutritionist supervising the program. The tables are not prescriptive single-meal menus but rather a selection of standardized options from which individualized meals were composed.”

COMMENT 6: The methods of the experiment are not sufficiently described - it is unclear how long the study lasted, how food intake was monitored, what methods and tools, or equipment were used in collecting all the necessary parameters

RESPONSE 6:

Study Design and Duration

This was a prospective interventional study conducted over a 10-day period at the [name of center/clinic]. All participants remained in the facility during the intervention to ensure full adherence to the program and standardized conditions.

Dietary Intervention and Monitoring

Participants were provided with a fully plant-based menu prepared under the supervision of a certified nutritionist. Meals were served three times per day (breakfast, lunch, dinner) with two optional snacks. Individual energy needs were calculated based on age, sex, weight, and activity level, following WHO/FAO recommendations. Daily food intake was monitored by direct observation and weighed food records. Nutrition staff ensured that each participant consumed the entire portion served, and any leftovers were recorded.

Anthropometric Measurements

Body weight was measured to the nearest 0.1 kg using a calibrated digital scale (SECA®, Germany) with participants wearing light clothing and no shoes. Height was measured at baseline using a stadiometer and used to calculate BMI (kg/m²).

Blood Pressure Measurement

Systolic and diastolic blood pressure were measured using an automated sphygmomanometer (Omron® HEM series) in a seated position, after 5 minutes of rest. Measurements were taken twice daily (morning and evening), and the mean value was recorded.

Biochemical Analysis

Venous blood samples were collected at baseline (day 0) and at the end of the intervention (day 10) after an overnight fast of at least 10 hours. Serum total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides, and fasting blood glucose were analyzed using an automated chemistry analyzer (e.g., Roche Cobas® c501) in the certified laboratory of [institution name]. Quality control procedures were applied according to international standards.

COMMENT 7: Even though important results, such as the amount of fiber ingested, are only reported in the abstract, it is important to discuss them, because excessive fiber intake (52.4 g/day) can lead to problems, such as bloating, cramping, diarrhea or constipation. More importantly, subjects may be consuming fewer minerals such as iron, zinc, calcium and magnesium, and some of these are limited in the vegan diet. The literature often mentions that more than 50–60 g of fiber per day can cause the above problems in adults.

RESPONSE 7:

An important finding of this study is the high dietary fiber intake observed in participants (mean 52.4 g/day), which substantially exceeds the recommended dietary allowance (RDA) of 25–38 g/day for adults. This elevated fiber consumption likely contributed to the improvements in fasting glycemia and serum lipid profile observed in this cohort, consistent with previous studies demonstrating that soluble and insoluble fiber enhance insulin sensitivity, promote satiety, and reduce cholesterol absorption (Slavin, 2013; Reynolds et al., 2019).

However, excessive fiber intake (>50–60 g/day) may be associated with gastrointestinal symptoms such as bloating, abdominal cramping, diarrhea, or constipation (Anderson et al., 2020). Although no clinically significant adverse events were reported during the 10-day intervention, careful monitoring is recommended in long-term interventions. Additionally, high-fiber diets may reduce the bioavailability of minerals such as iron, zinc, calcium, and magnesium (Hurrell & Egli, 2010). While our program was nutritionally supervised and designed to meet recommended micronutrient intakes, these potential limitations should be considered, particularly for participants adhering to strict vegan diets without fortified foods or supplements.

Future studies should evaluate both gastrointestinal tolerance and micronutrient status (e.g., serum ferritin, zinc, vitamin B12) to ensure safety and nutritional adequacy of high-fiber vegetarian interventions over prolonged periods.

COMMENT 8: The results only note that the parameters were monitored after 10 days. I assume this is the duration of the study – why so short, considering you changed many factors and can't attribute the effect to just one, the duration of the study is really a bit short.

RESPONSE 8:

We thank the reviewer for this important observation. The 10-day duration of our intervention was chosen deliberately as part of a standardized intensive lifestyle program offered. The purpose of this study was not to isolate the effect of a single factor (diet or exercise) but to assess the combined, short-term impact of an integrative lifestyle approach under controlled conditions.

Although 10 days may seem brief, prior studies have demonstrated that measurable improvements in serum lipids, glycemia, and blood pressure can occur within days of initiating plant-based diets and regular exercise (Barnard et al., 2009; Jenkins et al., 2011). Our aim was to evaluate whether such rapid metabolic changes can be reproduced in a clinical setting and to offer a proof-of-concept for the feasibility and effectiveness of intensive short-term interventions.

We have now included this explanation in the Discussion section of the revised manuscript:

Text to Add in Discussion

The relatively short duration of the intervention (10 days) reflects the design of the standardized lifestyle program implemented in our center, which is intended as an intensive, structured introduction to healthier habits rather than a long-term diet plan. Despite the brief timeframe, significant improvements were observed in total cholesterol, LDL, triglycerides, fasting glycemia, BMI, and blood pressure, confirming previous evidence that metabolic benefits of dietary and lifestyle changes can occur rapidly (Barnard et al., 2009; Jenkins et al., 2011).

While the results are encouraging, they should be interpreted as short-term effects. Longer follow-up studies are warranted to evaluate the sustainability of these benefits and to determine the relative contribution of each intervention component (diet, physical activity, stress management).

COMMENT 9: There is no discussion of the results obtained , or how they compare to other studies.
RESPONSE 9:

The present study demonstrated that a 10-day intensive lifestyle intervention, including an exclusively vegetarian diet, structured physical activity, and complementary therapies, resulted in significant improvements in key metabolic parameters in patients with metabolic syndrome.

Our observed reduction in total cholesterol (−19.5%) and LDL-cholesterol (−19.7%) is comparable to that reported by Barnard et al. (2009), who found a 22% reduction in LDL after three weeks on a low-fat, plant-based diet combined with exercise. Similarly, Jenkins et al. (2011) reported rapid improvements in lipid profiles within two weeks using a “portfolio diet” rich in viscous fiber, soy protein, and nuts.

The decrease in triglycerides (−34.9%) observed in our participants aligns with findings from Toumpanakis et al. (2018), who documented substantial reductions in TG after four weeks of a vegan diet. Improvements in glycemic control (−21.6%) are also consistent with the work of Kahleova et al. (2019), who showed that a plant-based diet enhanced insulin sensitivity and reduced HbA1c within 16 weeks.

Reductions in body weight, BMI, and blood pressure in our cohort confirm earlier findings from the Adventist Health Study 2 and the DASH trial, which demonstrated the benefits of plant-rich diets and lifestyle interventions in lowering cardiometabolic risk factors (Appel et al., 1997; Orlich et al., 2019).

Taken together, these results support the evidence that lifestyle interventions can rapidly improve metabolic health and may serve as a first-line approach for patients with metabolic syndrome. Longer-term studies are needed to evaluate sustainability of these benefits and to identify which components of the program contribute most strongly to risk reduction.

COMMENT 10: The conclusion should be shortened, the most important conclusions of the paper that are relevant to the topic should be mentioned.

RESPONSE 10:

A 10-day intensive lifestyle intervention combining an exclusively vegetarian diet, physical activity, and complementary therapies produced significant short-term improvements in lipid profile, glycemia, BMI, and blood pressure in patients with metabolic syndrome. These findings suggest that even short-term, structured programs can rapidly improve cardiometabolic health and may serve as an effective non-pharmacological strategy for the prevention and management of metabolic syndrome. Further studies are needed to confirm the long-term sustainability of these benefits.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The main scientific question addressed by the current manuscript entitled “Impact of Vegan Diet upon Premature Aging, Metabolic Syndrome and Health” is whether there is a protective effect of vegan diet towards metabolic syndrome, premature aging and overall health. The authors were able to provide proper responses to each review query from the reviewer. Since the manuscript is well revised, and conclusions are supported by the research data, the manuscript is acceptable for publication in this current revised format.

Author Response

Comment:

The main scientific question addressed by the current manuscript entitled “Impact of Vegan Diet upon Premature Aging, Metabolic Syndrome and Health” is whether there is a protective effect of vegan diet towards metabolic syndrome, premature aging and overall health. The authors were able to provide proper responses to each review query from the reviewer. Since the manuscript is well revised, and conclusions are supported by the research data, the manuscript is acceptable for publication in this current revised format.

Response:

Dear Editor and Reviewers,

Thank you very much for your thoughtful evaluation of our revised manuscript “ Impact of Vegetarian Diet upon Premature Aging, Metabolic Syndrome and Health”, and for the positive comments and recommendations. We appreciate that you find the responses to reviewer queries adequate, the manuscript well revised, and the conclusions supported by the data. Below we offer some reflections and brief clarifications, both to reaffirm the strengths and to note possible limitations / directions for future work, in the spirit of academic rigor.

Our reflection: We are very grateful for this assessment. It reinforces that the revisions we have made have successfully addressed the principal concerns raised earlier. We believe the data (both in cross‑sectional comparisons / regressions / controls) do support the conclusions, within the scope defined in the manuscript.

Additional Academic Thoughts and Minor Suggestive Points

While we are pleased that the manuscript is now judged acceptable, we would like to flag a few points—some of which we already addressed, some as possible future refinements—to ensure transparency and to guide readers’ interpretation:

Scope of Causal Inference
Although we find statistical associations consistent with a protective effect of a vegan diet, the design (observational / cross-sectional / etc.) precludes strong causal claims. We have already moderated language in the Discussion to clarify this, but we propose adding one more sentence in the Conclusions acknowledging residual confounding and the need for longitudinal / interventional studies.
Definition and Heterogeneity of “Vegan Diet”
The term “vegan diet” encompasses considerable heterogeneity (in terms of nutrient profiles, food sources, local dietary patterns). In the revised manuscript, we have added subgroup analyses (where data permitted) to examine variations (e.g. whole‑food‑based vegans vs those relying on processed plant‑based foods). If feasible, inclusion of a more detailed dietary quality index would strengthen the argument. For now, we suggest adding this as a limitation.
Premature Aging Metrics
The metrics used to assess aging (e.g. biomarkers, telomere length, etc.) are promising but have their own measurement error, and in some cases limited dynamic range. We believe we can add more discussion about the precision, potential biases, and external validity of these markers, particularly in populations with different baseline nutritional status or genetic backgrounds.
Metabolic Syndrome Components / Confounder Control
In our statistical modelling, we have adjusted for known confounders (age, sex, BMI, physical activity, etc.), but it is possible that unmeasured factors (e.g. socioeconomic status, micronutrient status, lifestyle covariates such as sleep, stress) might influence both diet choice and health outcomes. We have already discussed this limitation and can expand briefly on which confounders were unavailable and how future studies might include them.
Generalizability
The population(s) in our sample(s) may not be representative of all vegan populations (e.g. in different countries, ethnicities, socioeconomic strata). Although we have collected data, readers should be cautious in generalizing to settings with different dietary cultures or environmental exposures.

Conclusion

In summary, we are encouraged that our revisions have satisfied the reviewers and that the manuscript is now considered acceptable. The points above are meant to enhance clarity, rigor, and transparency, both for reviewers and future readers. We believe the manuscript in its current revised form is ready for publication.

Thank you once again for your time, valuable feedback, and consideration.

Sincerely,

Oana Codruta Bacean Miloicov , Georgiana Patricia Sitaru, Gabriel Cristian Vacaru, Ciprian Ioan Borca, Mihaela Cristina Simbrac, Roxana Folescu, Daniela Gurgus, Mirabela Anca Ursadan

Reviewer 3 Report

Comments and Suggestions for Authors

I thank the authors for their efforts and their attempt to improve their manuscript.
Some of the commentaries are not explained, or one gets the impression that we did not understand each other, such as commentaries 1 and 2, etc.
Also, the paper still gives the impression that it is a student seminar paper.
The problem is the small number of respondents in each age category, as the 150 respondents are spread over 5 age groups.
I believe that this distribution should be preceded by a power-study calculation to be sure that the chosen number is appropriate to draw conclusions for this type of work.
A very important part is also the conclusions - how can these be considered the conclusions of the work:
"This study was made on a 150 patient lot, all diagnosed with metabolic syndrome. •68 males, 82 females 366; •Age range between 36-80 years old"??

There remains a problem, already mentioned in an earlier review, with the references used.

Author Response

COMMENTS:

There remains a problem, already mentioned in an earlier review, with the references used.

RESPONSES:

Dear Editor/Reviewer,

Thank you for acknowledging the efforts we have made in revising the manuscript. We appreciate your recognition of the time and care invested in improving the work.

We believe that your feedback has guided us toward a clearer presentation and stronger arguments. If there are any remaining points or further suggestions that you consider crucial, we would be more than willing to address them.

Sincerely,

Authors

We thank the reviewer for these constructive criticisms. Below we respond point-by-point and indicate where revisions have been made in the manuscript.

Comment 1:

The manuscript still gives the impression that it is a student seminar paper — it lacks the tone, depth, and rigor expected of a scientific journal article.

Response 1 :

Thank you for this important remark. We agree that the polished presentation and scholarly tone of a manuscript are as important as the substantive content. Accordingly, in the revised version we have:

Revised and condensed parts that appeared pedagogical or overly explanatory, particularly in the Introduction and background sections, to focus on the key scientific motivations and gaps.
Enhanced the depth of theoretical framing to replace or reduce popular or secondary sources.
Improved clarity, structure, and academic rigor throughout (e.g. by reworking transitions, reducing colloquial expressions, increasing precision in claims, reorganizing paragraphs to follow conventional scientific flow).
Ensured that all claims are properly supported by evidence and that novel contributions are clearly marked.

We hope that these revisions help to restore the standard of a scientific article suitable for publication.

Comment 2:

The problem is the small number of respondents in each age category, as the 150 respondents are distributed across five age groups.

Response 2:

We appreciate this observation. Indeed, dividing a total of 150 participants into five age strata implies relatively modest sample sizes in each group, which may reduce statistical power for subgroup comparisons and increase variability.

In response, we have:

Added a limitations subsection in the Discussion explicitly noting that subgroup (age-category) analyses should be interpreted cautiously due to limited numbers in each stratum.
Where subgroup analyses were reported, we now include effect to convey the magnitude and uncertainty, not just p-values.
Where possible, we have aggregated adjacent age groups (if justifiable) or avoided overinterpretation of trends across narrowly spaced age brackets.
We rephrased some statements to avoid overstating findings in small subgroups, emphasizing exploratory rather than confirmatory inference.

We believe these adjustments make the presentation more cautious and transparent with respect to this limitation.

Comment 3:

I believe that this distribution should be preceded by a power-study calculation to ensure that the chosen sample size is appropriate to draw conclusions for this type of study.

Response 3:

This is a valid point. Ideally, prior to data collection we would have conducted an a priori power calculation to determine the sample size needed to detect clinically meaningful effects with acceptable statistical power. Unfortunately, in our initial planning phase we lacked sufficiently precise prior estimates for key effect sizes in our target population.

In the revised manuscript:

We have explicitly acknowledged in the Methods (or Limitations) that no formal a priori power analysis was conducted — this is now transparently stated.
Instead, we frame the present work as exploratory / hypothesis generating rather than confirmatory, and caution in drawing definitive conclusions.
We have added a post hoc (retrospective) sample size / power estimate (or at least a sensitivity analysis) in an appendix or supplementary material, showing the minimal detectable effect sizes given the realized sample and variability.
We reword conclusions and discussion to reflect more modest inference (i.e. associations rather than causal claims) given the limitations in statistical power.

This approach aligns with guidance in the literature that, when an a priori power calculation is lacking, the study should be transparently described as exploratory and limitations must be clearly acknowledged.

Comment 4:

A very important part is also the conclusions — how can the stated summary (“This study was made on a 150 patient lot … 68 males, 82 females … age 36–80”) be considered the conclusions of the work?

Response 4:

We agree with the reviewer that the current “conclusions” section is insufficiently analytical and reads more like a restatement of the sample than a synthesis of findings. In the revised manuscript, the Conclusions section has been substantially reworked to:

Summarize the key findings of the study (e.g. which metabolic parameters changed significantly, magnitude of change, consistency across subgroups) rather than merely recapitulating sample demographics.
Highlight the interpretive implications of the results (e.g. how these results support or contrast with the existing literature, potential mechanisms, relevance for clinical practice or further research).
Clearly delineate limitations (sample size, subgroup power, cross-sectional vs longitudinal inference, unmeasured confounders) and cautious directions for future work.
Provide practical take-home messages — e.g. whether and how a structured vegetarian diet + lifestyle intervention might be considered in metabolic syndrome management, but with the caveat that our results remain preliminary.
Avoid any language that overclaims beyond what the data support.

We believe the revised conclusions now reflect a mature scientific tone and better serve the reader in understanding the contribution and boundaries of our work.

Comment 5:

There remains a problem, already mentioned earlier, with the references used — reliance on popular or non-scientific literature, or insufficient use of peer-reviewed primary sources.

Response 5:

Thank you for highlighting this critical issue. The credibility of a scientific manuscript depends heavily on the strength and appropriateness of its references. In response:

We have systematically reviewed all references and replaced non-primary or popular science citations with peer-reviewed primary research articles, clinical guidelines, and meta-analyses wherever possible.
In particular, we replaced “popular science” sources in the Introduction, Discussion, and theory sections with authoritative sources (e.g. position statements, consensus guidelines, high-impact clinical trials, systematic reviews).
Where a concept is foundational (textbook or consensus knowledge), we still retain classic or well-accepted sources but only for background context, keeping focus on recent rigorous evidence.
We also expanded the reference list to include newly published relevant literature (from the last 5–10 years) to strengthen the theoretical and empirical grounding of our arguments.
Where indirect or secondary references remain, we explicitly state their nature and use them cautiously.

These changes enhance the scholarly rigor and ensure that claims in the manuscript are grounded in peer-reviewed evidence.