Abstract
Background
The National School Lunch Program (NSLP) provides >30 million meals to children daily; however, the specific nutrient composition of NSLP-selected and consumed meals for students from lower income and racial/ethnic minoritized backgrounds is unknown.
Aims
To quantify the nutrients in school lunch selection and consumption among students participating in the NSLP and compare these values to nutrient recommendations.
Method
Students (1st–5th graders; 98.6% from racial/ethnic minoritized backgrounds; 92.5% NSLP participation) from six Title I elementary schools serving universal free meals participated. Digital images of students’ lunch meal selection and consumption were obtained (n = 1,102 image pairs). Plate waste analyses quantified portions consumed. Nutrient composition of students’ lunch selection and consumption were calculated and compared with the 2010 Healthy Hunger-Free Kids Act and 2009 Institute of Medicine recommendations.
Results
Most lunches selected (59%–97%) met recommendations for all nutrients except for total calories (23%), vitamin C (46%), and dietary fiber (48%). Based on lunch consumption, most students’ lunches met recommendations for sodium (98%), protein (55%), calories from fat (82%), and saturated fat (89%); however, few met recommendations for total calories (5%), calcium (8%), iron (11%), vitamin A (18%), vitamin C (16%), and fiber (7%).
Discussion
Meals selected met most nutrient recommendations for the majority of children; yet overall consumption patterns reflect suboptimal nutrient intake.
Conclusion
Meals served under the NSLP policy mandates align with recommended nutrient patterns, highlighting the importance of maintaining these standards. Strategies to optimize children’s intake of nutrient-rich portions of these meals are needed to optimize policy impact.
Keywords
Nutritional inequities are observed among children from lower income and racial/ethnic minoritized backgrounds (Hiza et al., 2013). Overall, these children consume fewer fruits and vegetables and more sodium, refined grains, added sugar, and saturated fats, compared with children from other sociodemographic backgrounds (Thomson et al., 2019). These suboptimal dietary patterns, resulting from systemic issues including racism and oppression (Satia, 2009), can yield key nutrient deficiencies such as low calcium, potassium, fiber, magnesium, and vitamin E (Suitor & Gleason, 2002).
Federally assisted meal programs, including the National School Lunch Program (NSLP), are essential to improving the diet quality of systematically oppressed populations (Satia, 2009). The NSLP provides a substantial portion of daily energy intake to >30 million children daily (U.S. Department of Agriculture, Food and Nutrition Services, 2019c) and, in 2009, the Institute of Medicine (IOM) recommended new meal standards to improve the nutritional quality of school-provided meals (Institute of Medicine, Committee on Nutrition Standards for National School Lunch and School Breakfast Programs, & Food and Nutrition Board, 2010). In 2012, the Healthy Hunger-Free Kids Act (HHFKA) enacted these changes (HHFKA, 2010) by establishing calorie, sodium, and saturated fat limits; setting fruit, vegetable, and whole grains requirements; and eliminating high-fat milk (U.S. Department of Agriculture, Food and Nutrition Services, 2012). These changes seem to have improved the overall nutritional quality of school-provided meals (Bergman et al., 2014; Cohen et al., 2014; Welker et al., 2016); yet further evidence is needed to quantify their impact on the actual nutrient composition of selected and consumed school meals.
To date, most researchers have examined children’s dietary intake by quantifying their overall diet quality and consumption of general food groups (e.g., fruits and vegetables), rather than of specific nutrients (e.g., vitamins and minerals, Cohen et al., 2014; Cullen & Chen, 2017; Kinderknecht et al., 2020). One prior study (Smith & Cunningham-Sabo, 2014) examined specific nutrient intake of children during school lunch. These findings—collected prior to implementation of the HHFKA—suggested that children met some nutrient intake recommendations (e.g., percentage of energy from fat and saturated fat, and calcium), and fell short of others (e.g., Vitamins A and C, and fiber). An examination of the specific nutrient composition in school lunches under the current NSLP guidelines is needed to provide a more current, comprehensive assessment of the dietary quality these meals provide. Furthermore, a detailed assessment of both nutrient selection and consumption is needed so that food policy makers can evaluate if: (1) the current NSLP guidelines offer foods and beverages with adequate nutrients compared to national recommendations, and (2) the extent to which children consume these selected foods and beverages.
Prior research in this area has been conducted in predominantly European American samples (Kinderknecht et al., 2020; Smith & Cunningham-Sabo, 2014). It is unknown if similar nutrient intake patterns are observed in lower-income, racial/ethnic minoritized children who receive universal free meals. It is crucial to include children from diverse racial and ethnic backgrounds in this research, as they rely on school-provided meals for a significant portion of their nutrient intake (Mirtcheva & Powell, 2009). Furthermore, efforts aimed at increasing children’s fruit and vegetable consumption during school lunch can help all children obtain essential nutrients, and particularly those most reliant on school meals. School salad bars are widely promoted as a strategy for increasing children’s nutrient consumption by offering greater variety and choice (Centers for Disease Control and Prevention, 2018; Harris et al., 2012; U.S. Department of Agriculture, Food and Nutrition Services, 2019d). Despite their widespread promotion, there are mixed findings regarding the influence of school salad bars on children’s fruit and vegetable consumption (M. A. Adams et al., 2015; Bean et al., 2018a; Bean et al., 2020; Slusser et al., 2007), suggesting that use of this approach to enhance diet quality in school-age children warrants further investigation.
This secondary analysis utilizes data from a study that examined children’s fruit and vegetable consumption in Title I schools (half of which had salad bars) serving universal free meals (Bean et al., 2020). Current study aims were to: (1) quantify children’s nutrient selection and consumption from their school lunch meal, and (2) determine the percentage of children who meet the HHFKA and IOM recommended intakes for each nutrient. In addition, as an exploratory aim, we examined the association between school salad bar presence and children’s nutrient intake.
Method
Study Design and Setting
This cross-sectional study was conducted in six Title I elementary schools from a single district in central Virginia. All students were eligible for free meals under the Community Eligibility Provision of the HHFKA (U.S. Department of Agriculture, Food and Nutrition Services, 2019a). Within this district, three schools with salad bars were randomly selected to participate and were matched with three schools without salad bars (i.e., control schools). Matching was based on percentage of racial/ethnic minoritized student enrollment (i.e., ≥85% or <85% African American/Latin American) and factors related to the lunchroom environment assessed in a prior study (Bean et al., 2019; see Bean et al. [2020] for complete study methods).
Participants
This district comprised mostly racial/ethnic minoritized students (>90% African American or Latin American) and >90% participated in the NSLP. First through fifth-grade students (~6–12 years of age) in enrolled schools who selected a reimbursable meal on the day of data collection were eligible to participate. NSLP participation ranged 85.6% to 99.8% across schools, and total attendance was N = 2,103 for all schools combined on the day of data collection.
Procedures
Consent Process
Parents were provided a letter detailing study procedures, and an opt-out consent option was provided. On the day of data collection, teachers read a script to the students prior to lunch detailing the study procedures; students could also opt-out if they chose. Prior to entering the lunchroom, a sticker was placed on those children’s shirts who opted out (<5% of eligible children), and the research staff did not approach them during data collection. All study procedures were approved by The Virginia Commonwealth University institutional review board.
Digital Images of School Lunch Meals
Children’s dietary intake during school lunch was obtained on a single day for each of the six schools. Data were collected on the same day for schools within a matched pair to ensure the same menu items were served at both schools. Rating days were chosen to be a typical weekday with a routine school lunch menu. Digital imagery plate waste methods were used to quantify all foods and beverages that children consumed at lunch (Bean et al., 2018b; Taylor et al., 2014; Williamson et al., 2003). These methods have been validated in school and lab-based settings with similar populations (Bean et al., 2018b; Smith & Cunningham-Sabo, 2014; Swanson, 2008; Taylor et al., 2014; Williamson et al., 2003).
Prior to data collection, cafeteria assessors were trained to follow a standardized protocol consistent with previous studies (Bean et al., 2018a; Cohen et al., 2013). Training included repeated practice taking digital images of mock lunch trays, from ~1-foot distance at ~45° angle using iPads (Apple, Cupertino, CA). Cafeteria assessors were taught strategies to minimize the disruption of lunchroom flow while maximizing the amount and quality of data collected. Research team leaders observed each assessor during training and ensured adequate skill development before data collection.
On the day of data collection, cafeteria assessors placed a label on each student’s tray as she/he/they exited the lunch line. Labels included a unique number, student’s grade, and were color-coded by the child’s sex. Before students sat down at their lunch table, cafeteria assessors took a digital image of their lunch tray (i.e., preconsumption image). After lunch, students left their tray with any uneaten foods and beverages on the table. Cafeteria assessors approached each tray and adjusted any visual obstructions (e.g., napkins, silverware) that covered leftover foods. Remaining beverages were poured into clear plastic measuring cups so the volumes could be seen and quantified. A second, postconsumption image was then taken using the same procedures.
Reference Portions for Foods and Beverages Offered
All schools followed the Offer Versus Serve model (U.S. Department of Agriculture, Food and Nutrition Services, 2012), allowing students to select their foods and beverages within NSLP guidelines (choosing at least 3 of the 5 NSLP meal components, with one being a fruit or vegetable). Schools within each matched pair offered the same menu items, with the exception that a salad bar was present at only one school within each pair. A detailed list of offered foods can be found elsewhere (Bean et al., 2020). Beverages included 100% fruit juice, strawberry and chocolate sugar-sweetened fat-free milk, and low-fat/fat-free white milk. Reference portions were obtained for all foods and beverages offered at each school. For preportioned items, research staff purchased, weighed, and photographed three portions of each item using a calibrated scale (Ozeri Pronto Digital Food Scale [Model ZK14-S; Ozeri Kitchen]). The average weight was used as the reference portion for that particular item. For self-serve items from the salad bar, reference portions for each item were created in ¼ cup increments by the lab dietitians (Bean et al., 2018b), and then weighed, averaged, and photographed. The school dietitian provided product information for all foods and beverages served, which were entered into the Nutrition Data Systems for Research software (Nutrition Coordinating Center, 2018) to obtain nutrient information on reference portions for each item.
Plate Waste Ratings of Digital Images
A separate team of undergraduate student researchers served as laboratory raters and were trained to evaluate images of lunch trays in order to quantify plate waste. These raters were not involved in data collection and were masked to study hypotheses. Raters underwent extensive training on visual assessment of foods and beverages captured in the digital images using methods validated in previous studies (Bean et al., 2018a; Bean et al., 2018b; Taylor et al., 2014). Interrater reliabilities were assessed and deemed strong (0.84–0.94; McHugh, 2012) after training.
Preconsumption images were matched with corresponding postconsumption images. Laboratory raters viewed the preconsumption and postconsumption image side-by-side, and recorded which foods and beverages were selected in the preconsumption image. For self-serve items, raters recorded the amount selected to the nearest ¼ cup. Raters then recorded the percentage of left of each item that remained as plate waste in the postconsumption image, in 20% increments using reference images and visual pie charts for assistance (Smith & Cunningham-Sabo, 2014; Williamson et al., 2003). The percentage of each food or beverage missing was assumed to have been consumed. Items that were not rated included foods where appropriate evidence of the expected remains (e.g., apple core) was missing from the postconsumption image, as these items could have been shared or discarded during lunch. Furthermore, supplementary foods not served in the schools (e.g., candy) were not rated, as they were unable to be weighed and measured in advanced to obtain starting portions. For quality control, 20% of ratable images were chosen at random to be double rated, in a counterbalanced manner across raters. Interclass correlations were reevaluated and remained excellent (0.81–0.90).
Nutrient Selection and Consumption
Nutrient selection and consumption values were calculated for each lunch meal using Nutrition Data Systems for Research nutritional information and plate waste ratings. Selection values were based on students’ full lunch meal of all selected items, whereas consumption values were based on the portions consumed. The amount of each nutrient selected and consumed for all items in the lunch meal was calculated for total calories (kcal), calories from fat (%), calories from saturated fat (%), protein (g), calcium (mg), iron (mg), vitamin A (RE), vitamin C (mg), fiber (g), and sodium (mg). Next, the percentage of students who met the HHFKA (U.S. Department of Agriculture, Food and Nutrition Services, 2012) recommendations for calories, % calories from saturated fat, and sodium was determined based on students’ lunch selection and consumption values for each nutrient. There were no HHFKA reference values for the remaining nutrients (% calories from fat, protein, calcium, iron, vitamin A, vitamin C, and dietary fiber), thus IOM recommendations (IOM, Committee on Nutrition Standards for National School Lunch and School Breakfast Programs, & Food and Nutrition Board, 2010) were used as reference values for these nutrients, consistent with methods previously applied (Smith & Cunningham-Sabo, 2014).
Statistical Analyses
A total of 1,326 image pairs were matched and rated. Of these, n = 171 (12.9%) were excluded due to the presence of supplementary foods not offered in the school meal, and n = 53 (4.0%) were excluded due to the selection of an entrée not offered at both schools within a matched school pair (e.g., leftovers from a prior day) given the potential impact on nutrient availability. Thus, n = 1,102 image pairs (83.1%) were included in these analyses. Means and standard deviations were calculated for students’ selection and consumption of each nutrient for the overall sample. Each student’s selection and consumption values for all nutrients were then compared with the HHFKA and IOM intake recommendations. The percentage of students who met each recommendation was calculated for the overall sample.
To evaluate differences in whether nutritional guidelines were met for each nutrient by school salad bar status, multilevel mixed models were first applied. The unit of analysis was an individual lunch tray. A significant interaction between Level 2 fixed effects of salad bar status and matched school pair (independent variables) prohibited interpretation of the effects of salad bar status. Therefore, we applied logistic regression models, stratified by matched school pair, post hoc, to explore the association between school salad bar status (independent variable) and meeting the respective nutrient guideline (yes/no; dependent variable) for selection and consumption of each nutrient, respectively. Child sex and grade were included in all models as covariates. False Discovery Rate (Benjamini & Hochberg, 1995) was applied to correct for multiple testing; corrected p values (indicated as q values) <.05 were considered significant. Analyses were conducted using SAS version 9.4 (SAS Institute, Cary, NC).
Results
Nutrient Intake
Students’ average lunch selection and consumption values for each nutrient are shown in Table 1. The HHFKA and IOM nutrient intake recommendations are also provided for reference. Students’ average lunch selection for each nutrient met the intake recommendations for all nutrients, with the exception of dietary fiber, for which students’ average lunch selection (8.1 g ± 2.7 g) was below the intake recommendation (>8.5 g). Students’ average lunch consumption for each nutrient met intake recommendations for the percentage of calories from fat, percentage of calories from saturated fat, protein, and sodium. In contrast, students’ average lunch consumption did not meet nutrient intake recommendations for total calories, calcium, iron, vitamins A and C, and dietary fiber.
Mean ± SD of Nutrients in Student’s School Lunch, Based on All Items Selected and Consumed, in Title 1 Elementary Schools With Universal Free Meals.
Note. Values based on n = 1,102 student lunch meals.
Nutrient intake recommendation from the Healthy Hunger-Free Kids Act. bNutrient intake recommendation from the 2009 Institute of Medicine. *Indicates if nutrient selection or consumption values met the school meal guidelines.
Comparison With Nutrient Guidelines
The percentage of students meeting the HHFKA and IOM nutrient intake recommendations based on their lunch selection and consumption values is shown in Figure 1. The majority of students selected a meal that met the recommendations for most nutrients, including calories from fat (95%), calories from saturated fat (96%), protein (97%), calcium (61%), iron (64%), vitamin A (59%), and sodium (78%). In contrast, fewer than half of students selected a lunch meal that met the recommendations for calories (23%), vitamin C (46%), and dietary fiber (48%). Based on lunch consumption, most students met recommendations for sodium (98%), protein (55%), calories from fat (82%), and calories from saturated fat (89%). Yet, considerably fewer met the recommendations based on their consumption total calories (5%), calcium (8%), iron (11%), vitamin A (18%), vitamin C (16%), and dietary fiber (7%). Of note, the sodium HHFKA guidelines were to consume less than 1230 mg, thus students could have not met these guidelines based on their school lunch selection (by selecting a meal with >1230 mg), and then met these guidelines based on their school lunch consumption (by consuming <1230 mg), if they did not consume their full lunch meal.
Students (%) who met nutrient intake recommendations from the Healthy Hunger-Free Kids Act (for calories, calories from saturated fat, and sodium) and the 2009 Institute of Medicine guidelines (for calories from fat, protein, calcium, iron, vitamins A and C, and dietary fiber), based on their school lunch meal in Title 1 elementary schools serving universal free meals.
Differences for Schools With Versus Without a Salad Bar
The percentage of students whose lunch met nutrient intake requirements for selection and consumption values based on the presence of a school salad bar, by school, is shown in Table 2. No consistent associations between salad bar status and meeting recommended guidelines were found. For some matched school pairs, differences were found between schools with a salad bar and schools without a salad bar; however, for other pairs, there were no significant differences between schools.
Percentage of Students Who Met Nutrient Intake Guidelines Based on School Lunch Selection and Consumption and Results (OR [95% CI] q-value) From Logistic Regression Models Evaluating the Association Between Salad Bar Status and Students Meeting Nutrient Selection and Consumption Guidelines (Referent Group = Control). Results Displayed by Matched Title 1 Elementary Schools Serving Universal Free Meals.
Note. Values based on n = 1,102 total student lunch meals. Significance based on q-values from False Discovery Rate correction for multiple testing. Student sex and grade were included in all models as covariates. NE = not estimable.
Discussion
This study provides a detailed description of children’s nutrient selection and consumption during a school lunch meal among predominantly African American and Latin American students attending Title I elementary schools serving universal free meals. Key findings indicate that a majority of students selected foods and beverages for their lunch meal that met most HHFKA and IOM nutrient recommendations; therefore, the meals provided met their intended nutrient goals under this policy mandate. However, based on the portions that students consumed, many did not meet certain nutrient intake recommendations, suggesting that additional strategies to increase students’ consumption of more nutrient dense portions of their meal are needed. Although some nutrient intakes differed based on the presence of a school salad bar, these findings were mixed, and no overarching conclusions can be made.
It is particularly important for students participating in the NSLP to receive adequate nutrients during school-provided meals, given that these meals constitute a large portion of their daily energy intake and these children often have fewer opportunities to consume healthy nutrients outside of the school setting (Mirtcheva & Powell, 2009). The majority of students selected a lunch meal that met most nutrient recommendations, except for dietary fiber, vitamin C, and total calories, suggesting that students have the opportunity to meet most nutrient needs in their lunch meal. However, further efforts could be made to increase the amount of vitamin C (e.g., citrus fruits, tomatoes, and potatoes) and fiber (e.g., beans, whole grains, and berries) offered.
These results should be considered within the current food policy climate in which legislation to roll back the more stringent NSLP guidelines has been enacted, with additional changes looming (U.S. Department of Agriculture, Food and Nutrition Services, 2020). These rollbacks raise significant concern regarding potential reductions in the nutritional quality of school meals for the most vulnerable children (U.S. Department of Agriculture, Food and Nutrition Services, 2018; U.S. Department of Agriculture, Food and Nutrition Services, 2020). For example, the U.S. Department of Agriculture rolled back the NSLP guidelines regarding whole-grain requirements in 2018 (U.S. Department of Agriculture, Food and Nutrition Services, 2018), which is concerning given that lunches selected in the current study were assessed prior to these rollbacks under the more stringent guidelines and did not meet IOM guidelines for fiber. Perhaps rather than additional rollbacks to healthy meal standards, policy and programmatic efforts should, instead, focus on strategies to optimize children’s intake of nutrient dense foods within the NSLP to reduce nutritional inequities.
Current results also indicate that only a minority of students met the nutrient intake recommendations for total calories, calcium, iron, vitamin A, vitamin C, and dietary fiber consumed at lunch, even though adequate amounts for many of these nutrients were selected. These findings build on prior work examining fruit and vegetable (Bean et al., 2020; Mazzeo et al., 2017) and added sugar consumption (E. L. Adams et al., 2020) during school lunch and highlight the need for strategies to increase children’s consumption of the nutrient-rich components from their selected lunch meal. Providing an adequate duration of time for the school lunch period, offering recess prior to lunch, developing tasteful and appealing recipes, and training lunchroom supervisors to encourage positive, calm eating environments have all been shown to improve children’s diet quality and consumption during lunch (Centers for Disease Control and Prevention, 2019; Gross et al., 2019; U.S. Department of Agriculture, Food and Nutrition Services, 2019b). Future research would benefit from examining which types of foods and beverages children tend to waste, in order to develop more targeted approaches for increasing consumption of specific nutrient-rich foods during school lunch. Furthermore, supplementary foods brought from home, which are often more palatable calorie-dense foods and beverages (Hubbard et al., 2014), likely compete with the nutrient-rich meals provided by the NSLP; thus, policies limiting the types and amounts of supplementary foods brought from home might improve the consumption of nutrient-dense foods served in the school lunch meal.
The current study included a racial/ethnic minoritized sample receiving universal free meals. A similar study was conducted in 2010, prior to the implementation of the HHFKA; this prior sample included mostly European American, elementary school students, where 35% to 64% were eligible for free or reduced-price meals (Smith & Cunningham-Sabo, 2014). Compared with this prior study, fewer students in the current investigation met nutrient intake recommendations. This disparity is concerning, as the current study’s sample is at greater risk for chronic diseases, including obesity (Caprio et al., 2008). These findings reinforce the need for additional efforts to increase children’s consumption of key nutrients selected in their lunch meal, particularly in similar populations of lower income African American and Latin American children participating in the NSLP.
Similar to prior reports, this study found no clear pattern between the presence of a salad bar and consumption of key nutrients (M. A. Adams et al., 2015; Bean et al., 2018a; Bean et al., 2020; Slusser et al., 2007). Although schools were matched based on factors related to their lunchroom environment, additional (unmeasured) environmental factors appeared to be more salient, and should be included in future research (e.g., noise, crowding, and interactions with school lunchroom monitors) to examine their potential influence on children’s dietary consumption patterns. Given the substantial promotion and funding to support school salad bars (Centers for Disease Control and Prevention, 2018; Chef Ann Foundation, 2020; U.S. Department of Agriculture, Food and Nutrition Services, 2019d), it is crucial to continue examining their impact on children’s dietary intake and identify ways to optimize their use.
Limitations of this study include the inability to quantify items that were spilled or shared among students during school lunch, which could have led to a misestimation of nutrient intake. Data collection also occurred in a single school district and might not generalize to other populations. Furthermore, nutrient intake and selection were quantified on a single day at each school and might have led to a misestimation of children who met certain NSLP guidelines that were intended for an average across a full week (e.g., total calories in lunch meal). The inclusion of racially and ethnically diverse students at greatest risk for chronic diseases and high NSLP participation are notable strengths. Moreover, this study is strengthened by the quantification of a variety of nutrients that are understudied within school food policy research, and the use of rigorous digital imagery methods that are minimally intrusive and able to be used within a natural setting.
This study has a number of important implications for school food policies. Specifically, it appears that, overall, the quality of foods and beverages offered met the guidelines for many children and nutrients. These data suggest that current NSLP guidelines are generally effective at offering sufficient nutrients to children during their school lunch meal. Future policy and programmatic efforts are needed to increase children’s consumption of nutrient-rich foods and beverages offered. It is concerning that since the implementation of the HHFKA, some NSLP guidelines have already been rolled back, as these data suggest that children were not consuming adequate nutrients from their school lunch meal prior to these rollbacks. As such, future rollbacks to NSLP nutritional guidelines are strongly discouraged (Buscemi et al., 2015), as these would likely result in lower consumption of key nutrients. Furthermore, districts might consider policies such as restricting or prohibiting supplementary foods brought from home, as these are often more energy-dense, nutrient-poor foods that compete with the meals provided by the NSLP. Future research should examine if supplementary foods brought from home are limiting children’s consumption of the lunch items provided by schools.
In conclusion, this study contributes to the growing evidence regarding the nutritional quality of school meals offered and consumed in the NSLP. These findings can be used to advocate for maintaining the current nutritional guidelines while implementing future policies addressing the school environment and behavioral strategies to optimize children’s consumption of key nutrients and meet their nutritional needs.
Footnotes
Acknowledgements
We acknowledge the Greater Richmond Fit4Kids, cafeteria assessors and raters, participating students, and Food and Nutrition Services staff for their tremendous contributions to this work.
Author Contributions
MKB and ELA formulated the research question. MKB, HAR, LMT, and SEM designed the study. MKB and SEM implemented the study procedures. LMT analyzed the data. ELA and MKB drafted the initial version of the manuscript. All authors reviewed and contributed substantially to subsequent drafts of the manuscript and approved the final version as submitted.
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the National Institutes of Health (R03HD088985 awarded to MKB and 2T32CA093423 for ELA postdoctoral effort). Additional support was provided from CTSA award UL1TR002649 from the National Center for Advancing Translational Science awarded to Virginia Commonwealth University and the Children’s Hospital Foundation. These funding agencies had no role in the design, analysis or writing of this article.
