Assessing the Efficiency and Sustainability of Sugar-Sweetened Beverage Tax in the African Context: A Systematic Review of Evidence

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors’ manuscript examines a highly relevant and widely debated issue in the field of fiscal policy and taxation. The topic is multidisciplinary in nature, as it encompasses financial, economic, social, and health-related dimensions. It is worth noting the substantial volume of literature reviewed and analyzed by the authors. While such breadth is characteristic of systematic literature reviews, in this manuscript the authors indeed deserve recognition for the exceptionally comprehensive range of sources examined. Given the topicality of the subject, it is also appropriate that most references come from recent years. The study follows a logical and coherent structure, comprising an introduction, a literature review, a methodological section, a discussion, and a conclusion.

Alongside these positive aspects, several critical remarks and recommendations can be made:

- Although the title of the study directs attention to the analysis of the issue within African countries, in a substantial portion of the main text this focus is diluted, and the analysis shifts towards a predominantly global perspective. Comparative analysis is indeed an important analytical tool, but in this case the comparative framework is not sufficiently developed, and the emphasis falls mainly on countries outside the African continent. This is further reflected in the relatively small number of African countries mentioned or meaningfully examined in the manuscript.

- The title of the study highlights an assessment of the effectiveness and sustainability of the sugar-sweetened beverage tax; however, the main text does not clearly operationalize the indicators or metrics through which such an assessment could be made. Only in the conclusion does the reader find some indication of what the authors consider to constitute “effectiveness”. Furthermore, although several findings from existing studies are referenced, the authors do not provide concrete quantitative estimates (e.g., price effects, changes in demand or sales, or the tax burden distribution between consumers and producers).

- The authors should clearly and precisely formulate their research hypothesis (or hypotheses) at the beginning of the study.

- In Section 3.2, the authors present in tabular form the main conclusions of the studies reviewed. Although this practice is common in systematic literature reviews, in this case the table spans more than twelve pages, which significantly affects the readability of the article. It is recommended that the authors restructure this extensive material by grouping the studies according to several well-defined criteria (similar to Table 1, but in greater detail), and present synthesized findings. Alternatively, the studies could be distributed across several smaller tables, with the corresponding discussion integrated after each, enabling the prospective reader to navigate the conclusions more easily

Author Response

I have attached a document containing your comments and our revision.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

In my opinion, the manuscript addresses a relevant public-health topic, yet several elements limit its clarity, methodological consistency, and overall contribution. My comments focus on those aspects that, from my point of view, would benefit most from substantial revision.

First, I consider that the framing of the research question is too broad. The manuscript aims to assess both the “effectiveness” and “sustainability” of sugar-sweetened beverage (SSB) taxation across Africa and selected global contexts, but the criteria used to evaluate these concepts are not clearly defined. From my perspective, the term “sustainability” is applied inconsistently: sometimes to long-term behavioural change, sometimes to political feasibility, and sometimes to fiscal durability. A more precise conceptualisation would reduce ambiguity.

Second, the methodological section raises concerns about transparency. Although the paper claims to conduct a systematic review, the description of search strings, inclusion and exclusion criteria, screening procedures, and quality-assessment methods is limited. In my view, the current level of detail does not meet PRISMA standards. Additionally, the decision to include studies published before WHO’s 2014 recommendation is insufficiently justified and introduces temporal heterogeneity that remains unaddressed.

Third, the tables summarising the reviewed studies are extensive but difficult to interpret. Many entries mix descriptive information with evaluative statements, and the distinction between African and non-African evidence is not consistently maintained. I consider that the manuscript would benefit from a more synthetic analytical approach, possibly through thematic clustering or narrative synthesis, rather than long enumerations.

Fourth, several conclusions appear stronger than the underlying evidence allows. The manuscript frequently asserts that sugar taxes “reduce intake” across contexts, although many cited studies report mixed or modest effects, or focus on price adjustments rather than consumption outcomes. From my point of view, causal claims should be moderated unless supported by consistent and comparable metrics.

Fifth, the discussion sometimes shifts from summarising empirical evidence to advancing normative policy arguments. While these insights may be valuable, they should be clearly distinguished from the findings of the review.

Finally, the manuscript contains numerous writing issues (repetitions, grammatical inconsistencies, and abrupt transitions) that reduce readability. A careful language edit would improve the manuscript’s clarity.

Overall, I believe the topic is important and the compiled evidence is potentially valuable. However, in my opinion, the manuscript requires significant methodological refinement, clearer conceptual definitions, and a more coherent synthesis before it can meet publication standards.

Comments on the Quality of English Language

In my view, the manuscript would benefit from substantial language improvement to clearly convey its arguments. Several sections contain grammatical inconsistencies, repetitive phrasing, and abrupt transitions that interrupt the flow of ideas. At times, key concepts are expressed in a vague or circular manner, making it difficult to discern the authors’ main analytical points. Strengthening sentence structure, ensuring consistency in terminology, and improving coherence between paragraphs would enhance the clarity and readability of the paper.

Author Response

We have attached a document containing your comments and our revisions.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Thank you for the opportunity of reading and reviewing your interesting manuscript.

The paper seeks empirical validation regarding the World Health Organization's advocacy for implementing sugar taxes to mitigate the consumption of sugar-sweetened beverages (SSBs) and reduce associated health risks, such as obesity and type 2 diabetes.

Despite these recommendations, empirical evidence regarding the effectiveness and long-term sustainability of such fiscal measures within the African context remains limited.

The authors perform a systematic review of studies conducted between 2014 and 2024 that assessed the impact of sugar taxes on SSB intake, product reformulation, and public acceptability. Their findings indicate modest success in countries like South Africa and Mauritius, while adoption across Africa is minimal. Globally, outcomes are heterogeneous, with some jurisdictions repealing the tax due to sociopolitical resistance.

While the topic is very actual and important, and the authors worked on the SLR, I have the following comments regarding their research:

1.the methodology, protocol, selection of papers are not clearly stated. Please detail these aspects

2.this shortcoming is particularly important in the case of African studies. Their number is very limited and therefore the relevance is limited and not clear.

3.the paper needs further developments to make it more solid and with relevance. The link with sustainability is not strong enough in my opinion, making this outlet not the most suitable for the topic of the paper.

4.the conclusion section and the recomendations section should be enhanced, as they are very weak and brief now.

Good luck!

Author Response

We have attached a document containing your comments and our revisions. 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript has undergone revision, but several major issues remain unresolved. The paper still requires substantial improvements before it can be considered for publication.

1. Conceptual Clarity. Although the authors expanded their description of sustainability, the concept remains inconsistently defined and applied. A clear and coherent conceptual framework for “effectiveness” and “sustainability” is still missing.

2. Methodological Transparency. The manuscript no longer follows PRISMA, but continues to be presented as a systematic review. Search strings, screening procedures, inclusion/exclusion criteria, and quality assessment remain insufficiently documented. The methodological approach needs full clarification.

3. Evidence Synthesis. The narrative has expanded, but the synthesis remains largely descriptive and repetitive. The review would benefit from thematic organisation and more critical integration of findings, especially regarding African vs. non-African evidence.

4. Strength of Claims. Several conclusions still overstate the available evidence. Causal statements regarding the impact of sugar taxes should be moderated and aligned with the mixed results reported in the reviewed studies.

5. Normative vs. Empirical Content. Policy recommendations are interwoven with empirical findings. These should be clearly separated and presented as implications rather than part of the evidence itself.

The manuscript requires clearer conceptualisation, robust methodological clarification, stronger analytical synthesis, and comprehensive language editing.

Comments on the Quality of English Language

Numerous grammatical errors, inconsistent terminology, and long, dense paragraphs persist. A thorough language edit is required.

Author Response

We have attached a document containing your comments and our revisions.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors, I appreciate your efforts to improve the paper. However, I consider that major structural revisions are still needed. My previous comments were not addressed in a sufficient manner and there are still major methodological flaws.

Author Response

We have attached a document containing your comments and our revisions.

Author Response File: Author Response.pdf

Round 3

Reviewer 2 Report

Comments and Suggestions for Authors

I believe that the manuscript has been sufficiently improved; therefore, I recommend publication in its existing form.

Reviewer 3 Report

Comments and Suggestions for Authors

Although there are still shortcomings, the authors put effort in revising the manuscript.