Exploring the effects of added sugar labels on food purchasing behaviour in Australian parents: An online randomised controlled trial

Devorah Riesenberg; Anna Peeters; Kathryn Backholer; Jane Martin; Cliona Ni Mhurchu; Miranda R. Blake

doi:10.1371/journal.pone.0271435

Peer Review History

Original SubmissionFebruary 8, 2022
17 May 2022 Decision Letter - Shahrad Taheri, Editor PONE-D-22-03985Exploring the effects of added sugar labels on food purchasing behaviour in Australian parents: an online randomised controlled trialPLOS ONE Dear Dr. Blake, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. Please submit your revised manuscript by Jul 01 2022 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. 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The PLOS ONE style templates can be found at https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf 2. Please provide additional details regarding participant consent. In the ethics statement in the Methods and online submission information, please ensure that you have specified what type you obtained (for instance, written or verbal, and if verbal, how it was documented and witnessed). If your study included minors, state whether you obtained consent from parents or guardians. If the need for consent was waived by the ethics committee, please include this information. Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice. [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Yes Reviewer #2: Yes ******** 2. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes Reviewer #2: Yes ****** 3. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: Yes Reviewer #2: Yes ****** 4. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes Reviewer #2: Yes ****** 5. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: The statistical analysis of the study was well thought out as was the sample size considerations. A sample size of 2,464 participants (352 participants for each of 7 treatment groups) was estimated to detect a 13% absolute difference in percentage participants selecting a high sugar product between intervention and control conditions (power=0.80; α=0.0083; Bonferroni adjustment for comparisons of 6 intervention conditions to control. The statistical analysis was fairly routine and well planned . The investigators compared participant demographic characteristics across labelling conditions, using chi squared tests. For the primary analysis, they compared the difference in the odds of participants selecting a high sugar product overall and for each product group, between each label condition compared to the control condition, using logistic regression. Secondary continuous outcomes were examined using linear regression for HSR and added sugar content of intended purchases . Analyses were adjusted for clustering to take account of repeated participants between categories. The results were varied and the analyses of this online RCT showed that the authors found no consistent impact of a range of added sugar labels on the intended purchases of selected high sugar packaged non-alcoholic beverages, breakfast cereals, and yoghurts. Evidence suggests labels may be most effective as a part of a suite of interventions to influence consumer and manufacturer behavior indirectly. The tables and figures were well formatted and easily interpretable. Reviewer #2: Dear Authors, I would like to suggest some changes or additions to your paper: line 57: I wouldn't say that "sugars in all forms provide little nutritional value and increase risk of non communicable diseases (...)" and so on. I think we can agree that a) we need to make a distinction about intrinsic and "free" sugars (as you actually do shortly afterwards, but maybe you can add something more here) and b) it all depends on the equation between caloric needs/portions/frequencies. If it is so, please rephrase and add something short that explains it. If we do not agree on this, please add references for your statement. Overall I find the results very interesting and I would like to see more emphasis on the importance of not believing that FOPLs alone can somehow be the solution we are looking for. The fact that the statements made by the respondents in my opinion clash with the results obtained, is not trivial and should not be underestimated. It seems that people want to be guided in their choices, except that in practice they choose based on a thousand different variables, ignoring the indications they have asked for. What are the implications for health policy? Perhaps your thoughts on this can help other researchers modify the kinds of questions to be asked or the objects of their research. Thank you for your work ****** 6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy. Reviewer #1: No Reviewer #2: Yes:** Claudia Penzavecchia [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step. https://doi.org/10.1371/journal.pone.0271435.r001
Revision 1
26 May 2022 Author Response We thank the editors and reviewers for their helpful comments in improving the manuscript. Below we respond point by point to the reviewer comments. We have made updates to the reference list where required to respond to reviewer comments. Journal Requirements: When submitting your revision, we need you to address these additional requirements. 1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf -Formatting has been updated in line with journal requirements. Note that font and spacing changes have not be track-changed for readability. 2. Please provide additional details regarding participant consent. In the ethics statement in the Methods and online submission information, please ensure that you have specified what type you obtained (for instance, written or verbal, and if verbal, how it was documented and witnessed). If your study included minors, state whether you obtained consent from parents or guardians. If the need for consent was waived by the ethics committee, please include this information. -In the online portal and in Lines 233-6 within the manuscript, ethical approval statement updated: “Ethical approval was granted by Deakin University Faculty of Health, Human Ethics Advisory Committee (reference number HEAG-H 115_2020). Participants provided informed consent, indicated by clicking the statement “I have read the plain language statement and I agree to participate” before continuing to the online survey.” Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice. -Reference list has been reviewed for completeness. References added since original submission, in response to reviewer comments below, are: 4. Makarem N, Bandera EV, Nicholson JM, Parekh N. Consumption of sugars, sugary foods, and sugary beverages in relation to cancer risk: a systematic review of longitudinal studies. Annu Rev Nutr. 2018;38:17-39. 38. Sleddens EFC, Kroeze W, Kohl LFM, Bolten LM, Velema E, Kaspers P, et al. Correlates of dietary behavior in adults: an umbrella review. Nutr Rev. 2015;73(8):477-99. 39. Houghtaling B, Holston D, Szocs C, Penn J, Qi D, Hedrick V. A rapid review of stocking and marketing practices used to sell sugar‐sweetened beverages in US food stores. Obes Rev. 2021;22(4):e13179. 42. Moore SG, Donnelly JK, Jones S, Cade JE. Effect of educational interventions on understanding and use of nutrition labels: A systematic review. Nutrients. 2018;10(10):1432. 43. World Health Organization. Guiding principles and framework manual for front-of-pack labelling for promoting healthy diet. Geneva: World Health Organization. 2019. 44. Backholer K, Beauchamp A, Turrell G, Ball K, Woods J, Martin J, et al. A framework for evaluating the impact of obesity prevention strategies on socioeconomic inequalities in weight. Am J Public Health. 2014;104(10):e43-50. Reviewer #1: The statistical analysis of the study was well thought out as was the sample size considerations. A sample size of 2,464 participants (352 participants for each of 7 treatment groups) was estimated to detect a 13% absolute difference in percentage participants selecting a high sugar product between intervention and control conditions (power=0.80; α=0.0083; Bonferroni adjustment for comparisons of 6 intervention conditions to control. The statistical analysis was fairly routine and well planned. The investigators compared participant demographic characteristics across labelling conditions, using chi squared tests. For the primary analysis, they compared the difference in the odds of participants selecting a high sugar product overall and for each product group, between each label condition compared to the control condition, using logistic regression. Secondary continuous outcomes were examined using linear regression for HSR and added sugar content of intended purchases. Analyses were adjusted for clustering to take account of repeated participants between categories. The results were varied and the analyses of this online RCT showed that the authors found no consistent impact of a range of added sugar labels on the intended purchases of selected high sugar packaged non-alcoholic beverages, breakfast cereals, and yoghurts. Evidence suggests labels may be most effective as a part of a suite of interventions to influence consumer and manufacturer behavior indirectly. The tables and figures were well formatted and easily interpretable. -We thank the reviewer for their time in reviewing our manuscript. Reviewer #2: Dear Authors, I would like to suggest some changes or additions to your paper: line 57: I wouldn't say that "sugars in all forms provide little nutritional value and increase risk of non communicable diseases (...)" and so on. I think we can agree that a) we need to make a distinction about intrinsic and "free" sugars (as you actually do shortly afterwards, but maybe you can add something more here) and b) it all depends on the equation between caloric needs/portions/frequencies. If it is so, please rephrase and add something short that explains it. If we do not agree on this, please add references for your statement. -We agree with the reviewer that the evidence of harm relates mainly to free sugars, and have amended the text to reflect this: -Amended lines 54-62: “Free sugars, particularly in the form of sugar-sweetened beverages, provide little nutritional value and increase risk of noncommunicable diseases, including obesity, cardiovascular disease, diabetes, and certain cancers (2, 3). ‘Free’ sugars include ‘added’ sugars - sugars added to foods and beverages by the manufacturer, cook, or consumer - plus sugars naturally present in honey, syrups, and fruit juices and fruit juice concentrate (1). Free sugars are distinct from ‘intrinsic’ sugars which are present in whole fruits and vegetables, and ‘milk’ sugars present in dairy products, for which there is minimal evidence of adverse outcomes (4).” Overall I find the results very interesting and I would like to see more emphasis on the importance of not believing that FOPLs alone can somehow be the solution we are looking for. The fact that the statements made by the respondents in my opinion clash with the results obtained, is not trivial and should not be underestimated. It seems that people want to be guided in their choices, except that in practice they choose based on a thousand different variables, ignoring the indications they have asked for. What are the implications for health policy? Perhaps your thoughts on this can help other researchers modify the kinds of questions to be asked or the objects of their research. Thank you for your work -Amended lines 400-423: “FOP nutrient labelling alone may not provide sufficient incentives for consumer behavioural change in real-world settings. Real-world RCTs with single-label FOP interventions have also failed to find impacts on purchasing (30, 31). The observed contrast with consumers’ anticipated effects and reported desire to select healthier options, may reflect the highly complex consumer choice environment (38). There are currently multiple strong incentives for consumers to pick less healthy alternatives, for example the visual stimulation of other on-pack marketing (39). There is widespread acknowledgement of the need to use multisector and multicomponent interventions to incentivise and support healthier consumer purchasing. In Chile, promising effects on the healthiness of consumer purchases associated with introduction of warning labels for products high in added sugar (40) are likely enhanced by concomitant interventions, including taxes, educational campaigns and advertising restrictions. Additionally, evidence suggests the HSR system introduction may have been associated with manufacturer reformulation in Australia and New Zealand (41); facilitating healthier intakes without requiring changes in consumer behaviour. -Added sugar on food labels is essential to support these policies on added sugar content, including healthy school food policies, taxation, and advertising restrictions. Evidence (42) and guidance to governments (43) suggests FOP labelling schemes should be accompanied by consumer education campaigns and targeting of population groups of concern including those with low literacy and numeracy. Complementary strategies are needed to target different contexts and consumer subgroups. For example, educational interventions (such as FOP schemes) may be more effective amongst those with higher education levels (44). Real-world point-of-purchase trials and natural experiments exploring these comprehensive policy approaches are needed to support government decision-making on effective multicomponent approaches to improving dietary intake.“ Attachments Attachment Submitted filename: Response to reviewers.docx https://doi.org/10.1371/journal.pone.0271435.r002
1 Jul 2022 Decision Letter - Shahrad Taheri, Editor Exploring the effects of added sugar labels on food purchasing behaviour in Australian parents: an online randomised controlled trial PONE-D-22-03985R1 Dear Dr. Blake, We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements. Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication. An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org. If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. Kind regards, Shahrad Taheri Academic Editor PLOS ONE Additional Editor Comments (optional): Reviewers' comments: https://doi.org/10.1371/journal.pone.0271435.r003
Formally Accepted
11 Aug 2022 Acceptance Letter - Shahrad Taheri, Editor PONE-D-22-03985R1 Exploring the effects of added sugar labels on food purchasing behaviour in Australian parents: an online randomised controlled trial Dear Dr. Blake: I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department. If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org. If we can help with anything else, please email us at plosone@plos.org. Thank you for submitting your work to PLOS ONE and supporting open access. Kind regards, PLOS ONE Editorial Office Staff on behalf of Dr. Shahrad Taheri Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0271435.r004

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