Effectiveness of Nutrition Interventions in Vending Machines to Encourage the Purchase and Consumption of Healthier Food and Drinks in the University Setting: A Systematic Review

University food environments typically offer an abundance of unhealthy foods, including through vending machines. This review evaluated the effectiveness of nutrition interventions in vending machines in the university setting. Ten databases were searched for experimental studies published up to July 2019, evaluating nutrition interventions that aimed to encourage the purchase or consumption of healthier foods and drinks in vending machines in the university setting. In total, 401 articles were identified, and 13 studies were included. Studies were pre-post test (n = 7, 54%), randomized controlled trials (RCTs) (n = 5, 38%), and non-randomized controlled trial (n = 1, 8%). Most studies were from the USA (n = 10, 77%) and were published between 2014 and 2018 (n = 9, 69%). Eight interventions (62%) reported positive change in outcomes, including increased number/proportion of sales or revenue from healthier items (n = 6), improved adherence to guidelines for the ratio of healthy/unhealthy products available (n = 1), and improved consumer perception of items available (n = 1). Effective interventions involved the promotion, reduced pricing, increased availability, and/or optimized product placement of healthier items within vending machines. Strategies to improve the nutritional quality of food and drinks in vending machines are warranted. This may be achieved by making healthier options more available and promoting them; however, more robust intervention studies are needed to determine effectiveness.


limit 8 to english language 60
Explanation of search terms: -The forward slash symbol (/) means that the term is a valid controlled vocabulary term which has been searched in the Subject Headings field of the database. -'mp' searches several fields at once: mp search looks in the Title, Original Title, Abstract, Subject Heading, Name of Substance, and Registry Word fields -'adj5' searches for both terms within five words of each other in either order.

Rationale
3 Describe the rationale for the review in the context of what is already known. 1-2 Objectives 4 Provide an explicit statement of questions being addressed with reference to participants, interventions, comparisons, outcomes, and study design (PICOS).

METHODS
Protocol and registration 5 Indicate if a review protocol exists, if and where it can be accessed (e.g., Web address), and, if available, provide registration information including registration number.
2 Eligibility criteria 6 Specify study characteristics (e.g., PICOS, length of follow-up) and report characteristics (e.g., years considered, language, publication status) used as criteria for eligibility, giving rationale.

2
Information sources 7 Describe all information sources (e.g., databases with dates of coverage, contact with study authors to identify additional studies) in the search and date last searched.

2-3
Search 8 Present full electronic search strategy for at least one database, including any limits used, such that it could be repeated.

Supplementary
Table S1 Study selection 9 State the process for selecting studies (i.e., screening, eligibility, included in systematic review, and, if applicable, included in the meta-analysis).

2-3
Data collection process 10 Describe method of data extraction from reports (e.g., piloted forms, independently, in duplicate) and any processes for obtaining and confirming data from investigators.
3 Data items 11 List and define all variables for which data were sought (e.g., PICOS, funding sources) and any assumptions and simplifications made. 3

Risk of bias in individual studies
12 Describe methods used for assessing risk of bias of individual studies (including specification of whether this was done at the study or outcome level), and how this information is to be used in any data synthesis.

Synthesis of results
14 Describe the methods of handling data and combining results of studies, if done, including measures of consistency (e.g., I 2 ) for each meta-analysis.

NA
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Section/topic # Checklist item Reported on page #
Risk of bias across studies 15 Specify any assessment of risk of bias that may affect the cumulative evidence (e.g., publication bias, selective reporting within studies).

NA
Additional analyses 16 Describe methods of additional analyses (e.g., sensitivity or subgroup analyses, meta-regression), if done, indicating which were pre-specified.

Study selection
17 Give numbers of studies screened, assessed for eligibility, and included in the review, with reasons for exclusions at each stage, ideally with a flow diagram.

3-4
Study characteristics 18 For each study, present characteristics for which data were extracted (e.g., study size, PICOS, follow-up period) and provide the citations.

7-12
Risk of bias within studies 19 Present data on risk of bias of each study and, if available, any outcome level assessment (see item 12). 13 Results of individual studies 20 For all outcomes considered (benefits or harms), present, for each study: (a) simple summary data for each intervention group (b) effect estimates and confidence intervals, ideally with a forest plot.

DISCUSSION
Summary of evidence 24 Summarize the main findings including the strength of evidence for each main outcome; consider their relevance to key groups (e.g., healthcare providers, users, and policy makers).

13-14
Limitations 25 Discuss limitations at study and outcome level (e.g., risk of bias), and at review-level (e.g., incomplete retrieval of identified research, reporting bias).

14-15
Conclusions 26 Provide a general interpretation of the results in the context of other evidence, and implications for future research. 15

FUNDING
Funding 27 Describe sources of funding for the systematic review and other support (e.g., supply of data); role of funders for the systematic review. For more information, visit: www.prisma-statement.org.