Prevalence and Implementation Practices of School Salad Bars Across Grade Levels

Design and rationale for evaluating the impact of salad bars on elementary school students' fruit, vegetable, and energy intake: a wait list control, cluster randomized controlled trial

BACKGROUND

Most children do not consume the recommended amount of fruit and vegetable (FV) servings. Changing the school food environment can be a cost-efficient, effective approach to improving children's dietary quality. There is great popular support for school salad bars as a means to increase children's FV intake within the National School Lunch Program (NSLP), yet empirical research is limited. Further, although FV consumption can facilitate healthy weight management if these foods replace high calorie items, there is a need to enhance understanding of salad bars' influence on children's diet quality and energy intake within the NSLP. This is particularly important to investigate in schools in communities characterized by high poverty, as students they serve are particularly likely to rely on school meals.

METHODS

This report describes the design and rationale of a federally-funded investigation that uses validated methods to evaluate school salad bars. This district plans to install salad bars into 141 elementary schools over 5-years, facilitating the conduct of a waitlist control, cluster randomized controlled trial. Specifically, 12 pairs of matched schools will be randomly selected: half receiving a salad bar (Intervention) and half serving pre-portioned FVs only, standard under the NSLP (Control). Thus, groups will have different FV presentation methods; however, all schools will operate under a policy requiring students to take at least one FV serving. Schools will be matched on Title I status and percent of racial/ethnic minoritized students. Intake will be objectively assessed at lunch in each school pair, prior to (baseline), and 4-6 weeks after salad bars are installed (post), yielding ~ 14,160 lunch observations throughout the study duration. Cafeteria sales and NSLP participation data will be obtained to determine how salad bars impact revenues. Finally, implementation factors and cafeteria personnel's perspectives will be assessed, to identify barriers and facilitators to salad bars use and inform sustainability efforts. Proposed methods and current status of this investigation due to COVID-19 are described.

DISCUSSION

Results will have great potential to inform school nutrition policies and programs designed to improve dietary quality and reduce obesity.

TRIAL REGISTRATION

Retrospectively registered (10/28/22) in clinicaltrials.gov (NCT05605483).

Design and rationale for evaluating salad bars and students' fruit and vegetable consumption: A cluster randomized factorial trial with objective assessments

Building healthy fruit and vegetable (FV) consumption habits early in life is critical for primary prevention. However, U.S. youth do not come close to meeting national recommendations for FV intake. School-lunch salad bars are one of the most heavily promoted ways to meet FV guidelines. Contrary to popular belief, no rigorous randomized trials have examined whether salad bars increase students' FV consumption. This paper describes the design and rationale of a federally funded trial to evaluate whether introducing salad bars in elementary, middle, and high schools affects students' FV consumption and waste during lunch. A cluster factorial randomized trial will test new salad bars against waitlist controls, with and without an additional marketing intervention (N = 36 schools, N = 6804 students: n = 12 elementary, n = 12 middle and n = 12 high schools). Objective plate waste measurements of individual student's selection of FVs, consumption, and waste will be conducted using digital scales. Primary aim includes comparing FV consumption in schools without salad bars to those with new salad bars by grade level. Secondary aims include: a) whether FV marketing impacts the success of salad bars for FV consumption; b) whether salad bars differentially result in more FV waste compared to traditional serving methods; c) cost-benefit of using salad bars for consumption over traditional serving methods. When complete, this study stands to be one of the most definitive on the effectiveness of salad bars and contextual factors impacting their success. Findings will provide evidence for how to best spend limited federal dollars to improve FV intake in schools. Trial registration: ClinicalTrials.gov Identifier: NCT03283033 (date of registration: 9/14/2017).

Strategies to Address the Complex Challenge of Improving Regional and Remote Children's Fruit and Vegetable Consumption

Fruit and vegetables (F&V) are imperative for good health, yet less than one per cent of Australian children consume these food groups in sufficient quantities. As guided by Social Cognitive Theory (SCT), this paper aimed to: (i) understand key informant perspectives of the amount, types and quality of F&V consumed by rural and remote Western Australian (WA) children; and, (ii) determine strategies that could increase F&V consumption among rural and remote WA children. This qualitative study included 20 semi-structured interviews with health, school/youth and food supply workers, focusing on topics including: quantity and type of F&V consumed and strategies to increase children’s consumption. A thematic analysis was conducted using NVivo qualitative data analysis software (Version 10, 2014. QSR International Pty Ltd., Doncaster, Victoria, Australia). Key informants reported children consumed energy-dense nutrient-poor foods in place of F&V. Strategy themes included: using relevant motivators for children to increase their preference for F&V (i.e., gaming approach, SCT construct of ‘expectations’); empowering community-driven initiatives (i.e., kitchen gardens, SCT construct of ‘environment’); increasing food literacy across settings (i.e., food literacy skills, SCT construct of ‘behavioural capacity’); developing salient messages and cooking tips that resonate with parents (i.e., parent newsletters, SCT construct of ‘self-control’); increasing F&V availability, safety, and convenience (i.e., school provision); and, considering the impact of role models that extend beyond the family (i.e., relatable role models, SCT construct of ‘observational learning’). Overall, a comprehensive strategy that incorporates relevant motivators for children and families, supports local initiatives, reinforces the range of role models that are involved with children and creates healthier environments, is required to increase F&V consumption among children.

Reliability and Validity of Digital Imagery Methodology for Measuring Starting Portions and Plate Waste from School Salad Bars

BACKGROUND

Scientifically sound methods for investigating dietary consumption patterns from self-serve salad bars are needed to inform school policies and programs.

OBJECTIVE

To examine the reliability and validity of digital imagery for determining starting portions and plate waste of self-serve salad bar vegetables (which have variable starting portions) compared with manual weights.

DESIGN/METHODS

In a laboratory setting, 30 mock salads with 73 vegetables were made, and consumption was simulated. Each component (initial and removed portion) was weighed; photographs of weighed reference portions and pre- and post-consumption mock salads were taken. Seven trained independent raters visually assessed images to estimate starting portions to the nearest ¼ cup and percentage consumed in 20% increments. These values were converted to grams for comparison with weighed values.

STATISTICAL ANALYSES

Intraclass correlations between weighed and digital imagery-assessed portions and plate waste were used to assess interrater reliability and validity. Pearson's correlations between weights and digital imagery assessments were also examined. Paired samples t tests were used to evaluate mean differences (in grams) between digital imagery-assessed portions and measured weights.

RESULTS

Interrater reliabilities were excellent for starting portions and plate waste with digital imagery. For accuracy, intraclass correlations were moderate, with lower accuracy for determining starting portions of leafy greens compared with other vegetables. However, accuracy of digital imagery-assessed plate waste was excellent. Digital imagery assessments were not significantly different from measured weights for estimating overall vegetable starting portions or waste; however, digital imagery assessments slightly underestimated starting portions (by 3.5 g) and waste (by 2.1 g) of leafy greens.

CONCLUSIONS

This investigation provides preliminary support for use of digital imagery in estimating starting portions and plate waste from school salad bars. Results might inform methods used in empirical investigations of dietary intake in schools with self-serve salad bars.

Prevalence of and Differences in Salad Bar Implementation in Rural Versus Urban Arizona Schools

BACKGROUND

Rural children consume more calories per day on average than urban children, and they are less likely to consume fruit. Self-service salad bars have been proposed as an effective approach to better meet the National School Lunch Program's fruit and vegetable recommendations. No studies have examined how rural and urban schools differ in the implementation of school salad bars.

OBJECTIVE

To compare the prevalence of school-lunch salad bars and differences in implementation between urban and rural Arizona schools.

DESIGN

Secondary analysis of a cross-sectional web-based survey.

PARTICIPANTS/SETTING

School nutrition managers (N=596) in the state of Arizona.

MAIN OUTCOMES MEASURED

National Center for Education Statistics locale codes defined rural and urban classifications. Barriers to salad bar implementation were examined among schools that have never had, once had, and currently have a school salad bar. Promotional practices were examined among schools that once had and currently have a school salad bar.

STATISTICAL ANALYSES PERFORMED

Generalized estimating equation models were used to compare urban and rural differences in presence and implementation of salad bars, adjusting for school-level demographics and the clustering of schools within districts.

RESULTS

After adjustment, the prevalence of salad bars did not differ between urban and rural schools (46.9%±4.3% vs 46.8%±8.5%, respectively). Rural schools without salad bars more often reported perceived food waste and cost of produce as barriers to implementing salad bars, and funding was a necessary resource for offering a salad bar in the future, as compared with urban schools (P<0.05). No other geographic differences were observed in reported salad bar promotion, challenges, or resources among schools that currently have or once had a salad bar.

CONCLUSIONS

After adjustment, salad bar prevalence, implementation practices, and concerns are similar across geographic settings. Future research is needed to investigate methods to address cost and food waste concerns in rural areas.