Climate change-induced shifts in the food systems and diet-related non-communicable diseases in sub-Saharan Africa: a scoping review and a conceptual framework

Objectives To determine the relationship between climate change, food systems and diet-related non-communicable diseases (DR-NCDs) in sub-Saharan Africa (SSA) and propose a conceptual framework for food systems in SSA. Design A scoping review. Eligibility criteria Studies included investigated the relationship between climate change and related systemic risks, food systems, DR-NCDs and its risk factors in SSA. Studies focusing on the association between climate change and DR-NCDs unrelated to food systems, such as social inequalities, were excluded. Sources of evidence A comprehensive search was conducted in ProQuest (nine databases), Google Scholar and PubMed in December 2022. Charting methods Data extracted from studies included author, study type, country of study, climate change component, DR-NCD outcomes and risk factors, and impacts of climate change on DR-NCDs. A narrative approach was used to analyse the data. Based on the evidence gathered from SSA, we modified an existing food system conceptual framework. Results The search retrieved 19 125 studies, 10 of which were included in the review. Most studies used a cross-sectional design (n=8). Four explored the influence of temperature on liver cancer through food storage while four explored the influence of temperature and rainfall on diabetes and obesity through food production. Cross-sectional evidence suggested that temperature is associated with liver cancer and rainfall with diabetes. Conclusion The review highlights the vulnerability of SSA’s food systems to climate change-induced fluctuations, which in turn affect dietary patterns and DR-NCD outcomes. The evidence is scarce and concentrates mostly on the health effects of temperature through food storage. It proposes a conceptual framework to guide future research addressing climate change and DR-NCDs in SSA.


GENERAL COMMENTS
Dear authors, thank you for the opportunity to read your study.As someone who has been monitoring developments in this field, I think this review is very much needed and it summarises the evidence to date and highlights the key areas for further work.I really think this study addresses a key topic at the right time and have some comments below for author consideration.
-I think it is important to adapt the HLPE global framework for DR-NCDs in SSA as it helps to clarify the pathways in a very complex causal relationship.I am only a bit concerned that your adapted version does not look particularly different from the original HLPE framework or its interpretations.
-The difference between climate change and unfavourable weather events on DR-NCDs.How does a study on the effects of humidity on liver cancer be regarded as the impact of climate on liver cancer?What level of humidity change over how many years is climate change?-What is the difference between the January and December database searches?Was the search repeated, and why? -Page 10, lines 3-4: "We included studies published in peerreviewed journals between 1995 and 2022."What did you do with the grey literature search then?Needs clarification.

VERSION 1 -AUTHOR RESPONSE
Response to Reviewer 1 Dear authors, thank you for the opportunity to read your study.As someone who has been monitoring developments in this field, I think this review is very much needed and it summarises the evidence to date and highlights the key areas for further work.I really think this study addresses a key topic at the right time and have some comments below for author consideration.
Response: Thank you for your thoughtful comments.We are pleased to hear that the review is valuable in addressing the current key topic and state of the art.The responses to the questions are as follows.
1.I think it is important to adapt the HLPE global framework for DR-NCDs in SSA as it helps to clarify the pathways in a very complex causal relationship.I am only a bit concerned that your adapted version does not look particularly different from the original HLPE framework or its interpretations.
Response: Thank you for your comment.We have now used the original HLPE framework (with permission from the HLPE copyrights team) in the methods to hypothesise the causal pathways; see Figure 1.HLPE-SSA has also been redrawn to better describe the evidence found in this review; see Figure 3.
2. The difference between climate change and unfavourable weather events on DR-NCDs.How does a study on the effects of humidity on liver cancer be regarded as the impact of climate on liver cancer?What level of humidity change over how many years is climate change?
Response: Thank you for your comment.Previously, we had classified the climate variable as humidity if a study examined how rising temperature leads to increased humidity and, in turn, liver cancer.To clarify this, we have renamed the climate variable to "temperature (related to increased humidity)."See page 11, line 320-324 and page13, lines 363-364; as well as Table 1 and Table 2.
3. What is the difference between the January and December database searches?Was the search repeated, and why?
Response: Thank you for your comment.The January database search was a pilot search to test the search terms, while the December database search was the main search and the one utilised in this review.We have now removed the reporting of the pilot search from the methods; see page 9, lines 251-256.
4. Page 10, lines 3-4: "We included studies published in peer-reviewedjournals between 1995 and 2022."What did you do with the grey literature search then?Needs clarification.
Response: Thank you for your comment.Grey literature was searched for, but we did not report these findings as we did not find relevant material for the review.However, we have now added the sections on grey literature search and reporting in the methods section, page 9, lines 247-249 and pages 9-10, lines 257-272.

Response to Reviewer 2
We appreciate your positive feedback regarding our article.We are pleased that you found the review interesting and consider it relatively unexplored.Below are the responses to the questions. 1. Thank you for the opportunity to review the manuscript entitled "Climate change-induced Shifts in Food Systems and Diet-related Noncommunicable Diseases in Sub-Saharan Africa: A Scoping Review and Conceptual Framework".I think this is a very interesting topic and relatively unexplored.The paper is very well written, and the aims are clear.Take care with your line numbers, they re-start on each page, which makes reviewer feedback tricky.Response: Thank you for your comments.We acknowledge our mistake regarding the line numbers and apologise for the inconvenience it may have caused during the review.We have addressed this issue in the revised manuscript.

Summary
Introduction 5. Line 57: I think changing behaviour/patterns of extreme weather is better than increasing frequency, some extreme weather events are not increasing, but instead changing in intensity and occurring out of season (https://www.nature.com/articles/s41558-022-01388-4).
Response: Thank you for your comment.We have replaced this with 'changing patterns of extreme weather events' on page 4, line 101.Methods 6. Line 53: Briefly state what you mean by the "food production pathway."I see, these now refer to the pathways in the first paragraph, perhaps consider restricting this so it says, "These include: (next paragraph) 1, The food production pathway ….., (next paragraph) 2, The food storage pathway…., etc Response: Thank you for your comment.We have now rewritten this section on pages 7-7, lines 161-196, as advised.
Response: Thank you for your comment.We apologise for the typing error.We have changed this to "conducive environment" on page 7, line 167.
8. Line 39: Not sure JBI was spelling out on first use.
Response: Thank you for your comment.We have now spelt it out on page 8, line 201.9. Line 9, page 9: Not sure you need number 3, I would image it will be written in some language.
24. Line 36, page 19: You are stating that you were not excluding based on language, but I assume you only searched in one language, so that biased your results, not just excluding local languages, but all languages that were not in the one you used.
Response: Thank you for your comment.Yes, this is true.We have now added this as a limitation of the study in lines 515-516.
Response: Thank you for your comment.This implies foetal famine exposure and refers to a situation where the developing foetus experiences inadequate nutrient supply during pregnancy due to famine with consequences on NCDs later in life.This section has been rewritten for clarity on page

GENERAL COMMENTS
Thank you for submitting your revisions, which were carefully addressed and clearly answered.I believe this has really strengthened your contribution and made your important findings and conclusions much easier to interpret.I have one further comment, regarding a previous comment which I do not feel was sufficiently answered.
Inclusion criteria 3 and previous revision comment 24: Including a paper because it was "written in any language" is not an inclusion criteria.As all papers are written in a language, and all papers would fall into this criteria, making it redundant.
You state that no language restrictions were implied to the search results, which is great.
However, unless you searched in every possible language, then not all languages will be included, only the ones that had an abstract or title in the language which you searched.
You need to modify your inclusion criteria to represent this more clearly.E.g., "Inclusion criteria 3. Studies which had an English abstract or title".If English was the only language you searched in?It looks like from Appendix 1, it was only English.
As it is, I could not replicate your study, as you do not state all the languages you searched in, which will massively bias your results.However, this is a bias of all reviews, as it is not realistic to search in every possible language.You just need to make it clear.
Thank you for your continued effort in improving your manuscript.

VERSION 2 -AUTHOR RESPONSE
Reviewer's comment: Thank you for submitting your revisions, which were carefully addressed and clearly answered.I believe this has really strengthened your contribution and made your important findings and conclusions much easier to interpret.I have one further comment, regarding a previous comment which I do not feel was sufficiently answered.
Response: Thank you for your feedback and appreciate the opportunity to improve the overall understanding and replication of our review.We are pleased to hear that our previous revisions strengthened the understanding of our findings and conclusions.
Reviewer's comment: Inclusion criteria 3 and previous revision comment 24: Including a paper because it was "written in any language" is not an inclusion criteria.As all papers are written in a language, and all papers would fall into this criteria, making it redundant.
You state that no language restrictions were implied to the search results, which is great.
However, unless you searched in every possible language, then not all languages will be included, only the ones that had an abstract or title in the language which you searched.
You need to modify your inclusion criteria to represent this more clearly.E.g., "Inclusion criteria 3. Studies which had an English abstract or title".If English was the only language you searched in?It looks like from Appendix 1, it was only English.
As it is, I could not replicate your study, as you do not state all the languages you searched in, which will massively bias your results.However, this is a bias of all reviews, as it is not realistic to search in every possible language.You just need to make it clear.
Response to comments: Our search was conducted in English which may have by default of the search engine returned mostly abstracts in English.We have revised the inclusion criteria and have adjusted it accordingly.Inclusion criteria 3 now states 'Had an English abstract or title'.See line 215, pg. 8.
don't mention floods at all in your results.Not sure I understand why there needs to be a sub-heading for "Conceptual framework"? in the discussion.I think throughout better consistency of sub-headings through methods, results and discussion would make your review easier to follow.
GENERAL COMMENTSThank you for the opportunity to review the manuscript entitled "Climate change-induced Shifts in Food Systems and Diet-related Introduction Line 57: I think changing behaviour/patterns of extreme weather is better than increasing frequency, some extreme weather events are not increasing, but instead changing in intensity and occurring out of season (https://www.nature.com/articles/s41558-022-01388-4).Methods Line 53: Briefly state what you mean by the "food production pathway" I see, these now refer to the pathways in the first paragraph, perhaps consider restricting this so it says, "These include: (next paragraph) 1, The food production pathway ….., (next paragraph) 2, The food storage pathway…., etc Line 6, page 8: What is a "conductive environment"?Line 39: Not sure JBI was spelling out on first use Line 9, page 9: Not sure you need number 3, I would image it will be written in some language.Line 46: Why the first 20 pages of Google Scholar?Line 58: I do not see "Appendix 1" in this manuscript, it would have Line 13-17, page 19: You talk about an "established framework", but you never actually explain this framework, and I think at the moment, its a major limitation of the manuscript.The "High-Level Panel of Experts" is something discussed in your abstract and summaries at the beginning, you then go back to mentioning in the methods, and it appears fundamental to the framework you are building your review on.However, nowhere in the introduction do you mention the framework, or the HLPE (e.g., who are they, what are they experts in, when were they formed, what are their aims?).So this makes understanding how you arrived on this framework and methods very challenging.Line 20-23: You do not provide evidence in your review for this, I cant see how Figure 3 is different to Figure 1.Line 36, page 19: You stating that you were not excluding based on language, but I assume you only searched in one language, so that biased your results, not just excluding local languages, but all languages that were not in the one you used.Line 48: What is "foetal famine"?Conclusion Also include some concluding remarks of what you found, not just what you didn't find or what still needs to be done.
Also include some concluding remarks of what you found, not just what you didn't find or what still needs to be done.Response: Thank you for your comment.We have included conclusions on the study findings and what needs to be done; see page 20, lines 539-550.