The importance of sodium reduction to decrease cardiovascular disease risk cannot be overstated.1 A large body of evidence supports the health benefits of lowering sodium in the diet of the average person and for special populations (eg, children, African Americans, those with cardiovascular disease, and older adults).2-4 The average amount of sodium that Americans (including children) consume daily remains substantial (>3400 mg per day) and significantly higher than the Dietary Guidelines for Americans recommendations (no more than 1500 mg per day for almost half of US adults and children).5,6 Although individual choice plays an important role, the environment is the critical driving force for this public health problem.7-12 As stated throughout this supplement, the main sources of sodium are restaurant and processed foods, including foods served in school cafeterias.3,13
The literature suggests that access to foods in schools influences children's dietary behaviors, both in the short term and in the long term.2,14 Thus, schools are increasingly seen as ideal places to improve nutrition, since US children consume more than one-third of their daily food intake in these environments.15,16 The recent updates to the US Department of Agriculture's (USDA's) nutritional requirements for the federally subsidized National School Lunch Program (NSLP) and the School Breakfast Program (SBP), for example, represent transformative opportunities for public health to incorporate and further accelerate sodium reduction in the daily processes of school districts, especially in low-income, urban areas. In Los Angeles County, this translated to an unprecedented opportunity to affect change in the nation's second largest school meal program-the program operated by the Food Services Branch (FSB) of the Los Angeles Unified School District (LAUSD).
In 2010, the Los Angeles County Department of Public Health (DPH) received funding from the Centers for Disease Control and Prevention's Sodium Reduction in Communities Program (SRCP) to reduce sodium consumption at the community level through the use of system-level and environmental change strategies.17 This funding allowed the DPH to accelerate its sodium-reduction effort (the Los Angeles County Sodium Reduction Initiative) by adding staff support and technical assistance resources to an existing departmental healthy food procurement initiative; the initiative is described elsewhere in this journal supplement.18 The LAUSD school meal program was among the institutional settings that were targeted by this sodium-reduction effort. For this particular program objective, the DPH in collaboration with the LAUSD was successful in introducing and incorporating a number of sodium-reduction strategies into the LAUSD-FSB menu planning process. The strategy-focused approaches that were introduced and implemented included the following: (1) sodium limits as part of the school district's comprehensive nutrition policy, menu planning (eg, taste tests with students and parents), and food procurement (eg, working with vendors to procure lower-sodium foods); (2) environmental modifications such as signage at point-of-selection or health education materials to promote consumption of more fruits and vegetables; and (3) an awareness campaign (I'm In) to prepare students and parents for forthcoming changes to the menu (Table 1).
In this article, we discuss the evaluation of menu changes made to the LAUSD school meal program, comparing the mean sodium levels by meal categories for school years (SY) 2010-2011 (pre-menu change) and 2011-2012 (post-menu change). Of particular interest is whether the incorporation of sodium limits in the new school meal program menu for 2011-2012 resulted in actual lowering of the mean sodium content for the meals served by the LAUSD-FSB and whether the changes in the sodium content met the sodium targets recommended by the Institute of Medicine (IOM); these targets were later adopted (post-menu change) by the USDA's Final Rule for school meals on January 26, 2012.2,3 The article concludes by discussing the implications of these changes to other school districts in Los Angeles County and nationally for districts interested in taking similar action.
Methods
The USDA NSLP and the SBP require reporting from all participating school districts for compliance purposes.19 In the LAUSD, interval reporting is based on analyses of nutritional content of the NSLP and SBP menus and monitoring of food production by meal categories: elementary (K-5) breakfast and lunch and secondary (6-12) breakfast and lunch. The OneSource Point-of-Service software (Horizon Software International, Duluth, Georgia) was used to analyze all 4 menus for nutritional content. OneSource uses the USDA database as the source for food nutrient data. The software is continually updated to provide necessary data as required by the USDA NSLP. The menu items were entered into the Point-of-Service system and analyzed for total fat, saturated fat, trans fat, food energy (kilocalories), carbohydrates, cholesterol, dietary fiber, protein, iron, calcium, sodium, and vitamins A and C; this article presents data for sodium only. Through a data-sharing arrangement with the LAUSD-FSB, the DPH gained access to these nutritional analysis data for the months of October 2010 and October 2011, which corresponded to the pre- and post-menu change periods that were selected for analysis. The DPH also gained access to the food production records (up to a total of 9 months per school year); the food production records provided information on leftovers and patterns of food selection among students by food categories (eg, entrees, sides, dairy products, condiments). Both data sets (nutritional analysis and food production records) were rigorously cleaned and processed iteratively by the DPH prior to the analysis.
Comparative analysis
The mean sodium levels before and after the new menu changes were estimated by analyzing the food offerings outlined in the menus. The corresponding nutritional analysis data and food production records were extracted from the data files for October 2010 and October 2011. The month of October was selected for this comparative analysis because it offered a reasonable time window of at least 6 weeks from the start of the school year to allow for all menu changes to be fully implemented. A length of 12 months between pre-menu change (SY 2010-2011) and post-menu change (SY 2011-2012) was selected to account for operational factors (eg, procurement costs that might affect the number and type of entrees/sides produced and offered; seasonal variability, such as quality and quantity of fruits and vegetables offered; and attrition [eg, elimination of flavored milk during the school year]). For SY 2010-2011, 4 different meal categories were offered at the LAUSD: elementary breakfast, elementary lunch, secondary breakfast, and secondary lunch. For SY 2011-2012, the breakfast categories were consolidated into one category because meal offerings were the same for both elementary and secondary breakfasts. In general, the choice of offerings for elementary breakfast and lunch (meal categories) was served to students in grades K-5 whereas secondary breakfast and lunch (meal categories) were served to students in grades 6 to 12. In some schools, the grade levels were mixed (eg, K-12, continuation schools, special education); these schools were excluded after sensitivity analyses revealed no difference in mean estimates when these schools were included versus excluded from the analysis. Schools that had missing data were also excluded from the analysis. In SY 2010-2011, the LAUSD comprised 916 schools; this number increased to 938 schools in SY 2011-2012. After applying the aforementioned exclusion criteria, final sample sizes for the comparative analysis were as follows: n = 683 for SY 2010-2011 and n = 728 for SY 2011-2012. These numbers reflect the availability of the data for the school site and the completeness of food production records to weight the data. Characteristics of the schools, including enrollment for SY 2010-2011 and SY 2011-2012, are given in Table 2.
Nutritional content data: Estimating mean sodium level per meal, by meal category
The nutritional content of the SY 2010-2011 and SY 2011-2012 menus was determined using the nutritional composition records for each menu item provided by the LAUSD; these data were ascertained using the nutritional analysis software described earlier to analyze information contained in menu recipes. Each meal in each meal category was offered as an assortment or a combination of entrees, at least one side, a milk option, and condiments related to the entree choice. To account for variation in student selection of entrees (eg, meat vs vegetable options), weights were determined using the food production records provided by the LAUSD and were applied to the mean estimates of sodium levels for each of the entrees offered in the menus. The number of entrees selected was calculated by subtracting the leftovers from the total food offered for each day. This number was used to determine the fraction of the total number of entrees served out of the total number of entrees made that day for students. Although the menu would often repeat itself throughout the month, nutritional content varied according to the daily popularity of each of the entrees. For example, the Cafe LA Coffee Cake was served on several occasions for breakfast in October 2010; however, the amount of sodium this item contributed to the daily nutritional content varied depending on how many students selected it compared with the other entree available. On any given day, for all meal categories, there were at least 2 entree options to choose from for both breakfast and lunch. The mean sodium levels for each meal were estimated on the basis of a formulaic series of calculations. These calculations took into account the mean estimates for entrees weighted by student selection pattern (as described earlier); the absolute or mean estimates for sides (sometimes only one side is offered during the meal period); the mean estimates for the choice of milk; and the mean estimates for condiments added (see equations A and B). The final estimates were based on averaging daily meal offering estimates over the month. Confidence intervals (95% CIs) were calculated for each mean estimate and used to assess whether a significant change was present in sodium content due to the new menu changes. Mean sodium levels were then compared against the IOM and USDA standards outlined in the final rule for school meals.2
The following formulas (equations A and B) for estimating mean sodium level per meal, based on the number of choices offered during the meal period, were used:
Data analysis and institutional review board considerations
All calculations were performed using Statistical Analysis Software (version 9.3; SAS Institute, Cary, North Carolina). Prior to the analysis, all data sets, data management protocols, and estimation procedures were reviewed and approved by the Los Angeles County DPH's institutional review board. Since nutritional analysis data and food production records contained no individual identifying information, they were considered exempt by the institutional review board.
Results
From SY 2010-2011 (pre-menu change) to SY 2011-2012 (post-menu change), the mean unweighted sodium levels per meal for elementary and secondary breakfast decreased by 33.8% and 53.5%, respectively. Post-menu change, the mean unweighted sodium levels per meal for elementary and secondary breakfast were both 494.3 mg (95% CI, 424.0-564.6), which met the IOM and USDA 2014-2015 elementary breakfast target and the 2022-2023 secondary breakfast target (Table 3). For secondary lunch, the mean unweighted sodium level per meal was 1089.8 mg (95% CI, 962.1-1217.6) post-menu change, a decrease of 4.2% from SY 2010-2011. For elementary lunch, however, the mean unweighted sodium level per meal increased by 10.2%.
Results were not as notable once student food selection patterns (weighted data) and condiments were considered in the analysis. After weighting, elementary breakfast mean sodium level per meal (including cond-iments) decreased by only 13.3% (mean difference = 79.5 mg) as opposed to the 33.8% decrease (mean difference = 252.5 mg) observed for the unweighted data. Similarly, the mean sodium level per meal for secondary lunch (including condiments) increased with weighting, diminishing the magnitude of the difference seen between SY 2010-2011 and SY 2011-2012 (Table 3).
Discussion
With the support of the LAUSD Board of Education and early engagement of students, parents, and community stakeholders, the LAUSD-FSB in partnership with the DPH successfully changed the food offerings of the school meal program for SY 2011-2012. In concert with the Los Angeles County Sodium Reduction Initiative, the DPH was able to strategically integrate sodium reduction (eg, sodium limits and other environmental modifications such as promotion of fruits and vegetables, which are low-sodium food options) into the broader, more comprehensive agenda on health, which was adopted by the LAUSD-FSB in its menu planning for SY 2011-2012. The present findings reflect these efforts and highlight the favorable changes that took place during the SRCP experience in the LAUSD.
Indeed, the present comparative analysis indicates that mean unweighted sodium levels for 3 of 4 meal categories decreased post-menu change, suggesting that applying sodium limits to school meals is a plausible intervention for large, urban school districts such as the LAUSD, which serves about 650 000 meals per day. The addition of weighting procedures to account for student selection pattern in the mean sodium estimates (per meal) was both innovative (not previously done with regularity for this type of analysis) and necessary to draw more realistic conclusions about this strategy's impact, as individual student choices play a critical role in determining the strength of system-level and environmental change interventions.11,14 The weighted results, for example, likely reflected variations in the student selection of entrees (eg, the students consistently chose more meat options than vegetable options). Similarly, condiments played a role and affected the magnitude of the decline in sodium averages. Condiments can add in excess of 44.3 to 317.9 mg of sodium to each meal (see footnotes in Table 3). Finally, the differences observed between the menus for SY 2010-2011 and SY 2011-2012 should be interpreted conservatively, ideally within the context of LAUSD's conversion from a nutrient-based menu planning process to one that is based on food categories (food-based) (Table 1). This conversion was undertaken in response to the new USDA Final Rule and likely contributed to the further lowering of mean sodium levels by the addition of more fruits and vegetables offered in the SY 2011-2012 menu.
Limitations
Results from the present analysis are subject to several limitations. First, the nutritional analysis data from the LAUSD were compiled using nutritional software that analyzed information from menu recipes. While this is generally considered an acceptable, high-quality alternative to laboratory nutrient analysis (gold standard), possible data entry and software user errors may have occurred and lessened the internal validity of the method.20 Second, cleaning, managing, and analyzing food production records was labor- and resource-intensive since these records are not collected for the sole purpose of evaluation. The records were also subject to a variety of coding errors. For example, schools sometimes coded an entree using the incorrect recipe ID or they mislabeled the meal category (eg, elementary breakfast rather than secondary lunch). Unlike entrees and sides, recordings of condiments quantity were frequently inconsistent in these records. Third, there was a small difference in the number of schools from SY 2010-2011 to SY 2011-2012 (difference = 45 schools) included in the analysis for each of the 2 years, which reflects the availability of food production records for each school. However, the results were not significantly influenced by this difference. Finally, missing data were commonly encountered during data analysis. This, however, was expected, as real-world data files are generally not as complete or rigorously cleaned as data collected for the sole purpose of research.
CONCLUSIONS
The use of strategy-focused menu planning as a mechanism to reduce sodium in school meals appeared to be promising, demonstrating favorable declines in mean sodium levels for at least 3 of 4 meal categories in the LAUSD. Student food selection patterns and condiments use, however, appeared to affect the strength of the intervention. More research and evaluation are clearly warranted to study these and other complex food selection behaviors and menu change interventions in public schools. Findings and lessons learned from this analysis provide real-world context and data that have utility for informing menu planning in other school districts interested in taking similar action as the LAUSD.
REFERENCES