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Research Project: Epidemiology of Childhood Diet and Obesity

Location: Children's Nutrition Research Center

2022 Annual Report


Objectives
Objective 1: The National Health and Nutrition Examination Survey (NHANES) (2001-2014 and later releases) will be used to identify diet-related risk factors for obesity, and other health outcomes in children, adolescents, and adults specifically: Objective 1A: Identify eating patterns in children, adolescents and adults by gender and ethnicity, Objective 1B: Examine the association between eating patterns and obesity and related health risk factors, Objective 1C: Examine the impact of individual foods, nutrients, and food-specific patterns on obesity and health outcomes in children, adolescents, and adults. Objective 1D: Identify the impact of eating patterns on dietary intake, nutrient adequacy, and diet quality. Objective 2: Examine the rural-urban differences in and associations between food security status, food availability, participation in Federal nutrition assistance programs, dietary intake, and obesity among children across the different age groups, i.e., 2-5 years, 6-11 years, 12-15 years and 16-18 years old. Subobjective 2A: Examine the rural-urban differences in food security status (FSS) of children across the various age groups. Subobjective 2B: Determine the association of FSS with food availability and participation in federal nutrition assistance programs (FNAP) among children, based on rural-urban residence. Subobjective 2C: Determine the association of FSS with dietary intake and diet quality among children, based on rural-urban residence. Subobjective 2D: Determine the association between FSS and weight status of children, based on rural-urban residence. Objective 3: Determine the relationship between children’s physical activity, diet, sedentary behavior, and sleep, on summer weight gain in children and the impact of parenting on these behaviors using data from the Early Childhood Longitudinal Kindergarten 2011 Cohort, the Family Life, Activity, Sun, Health, and Eating study and others as appropriate. Subobjective 3A: Conduct a systematic review and meta-analysis of interventions for obesity prevention and treatment among school-age children targeting the summer months when children are not in school, and assessing their impact on BMI, PA, diet, sedentary behavior, and sleep. Subobjective 3B: Determine the number and types of distinct categorical body mass index (BMI) percentile trajectories in a longitudinal early childhood cohort and examine whether children's physical activity (PA), diet, sedentary behavior, sleep timing, child care arrangements, and medication usage predict developmental trajectory membership in order to inform obesity prevention interventions. Subobjective 3C: Examine the relationship between adolescents' BMI, physical activity, sedentary behavior, sleep and diet during in-school and out-of-school times and the impact of parenting practices on these behaviors.


Approach
Today, an estimated 16% of US children and adolescents are overweight and 17% are obese, and the prevalence continues to rise. Obesity is the result of energy imbalance, and dietary behaviors associated with overweight need to be examined. The long-term objective of this project is to better understand eating patterns, impact of food security status, rural/urban differences, and seasonal differences in weight-related behaviors that influence obesity and other health risk factors in children, adolescents, and adults. Few attempts have been made to identify broader eating patterns and their association with weight status and other chronic disease risk factors. This project aims to identify eating patterns--in terms of food sources, food group consumption, and nutrient intake--that may be associated with obesity and other health risk factors in children, adolescents, and adults using extant datasets. Also, food insecurity is related to poor dietary behaviors that can lead to net positive energy balance and obesity. Thus, we aim to assess the impact of food security status on dietary intake and quality, food availability, participation in federal food assistance programs, and weight status based on rural/urban residence. Finally, we will examine other behavioral predictors of children’s weight gain (i.e., sleep, physical activity, sedentary behavior) using the school-summer paradigm. Together this research will facilitate a better understanding of how to behaviorally target interventions to prevent obesity during childhood.


Progress Report
Objective 1D was addressed to identify the impact of eating patterns (i.e. individual foods) on dietary intake, nutrient intake and diet quality. The 2020 Dietary Guidelines Advisory Committee recognized calcium, potassium, vitamin D, and dietary fiber as nutrients of public health concern because low intakes were associated with adverse health outcomes. To help address the low intake of nutrients of public health concern, the 2020 Dietary Guidelines for Americans recommend 2.5 servings of dairy products for children 4-8 years of age and three servings for those 9-18 years of age. Flavored milk is a viable option for getting closer to meeting the recommended intakes of dairy products and selected nutrients. It is critical to understand the nutritional contribution of flavored milk in the diets of children in light of the new added sugars recommendation balanced with its positive contribution to the nutrients of public health concern. The objective of this study was to examine the nutritional contribution of flavored milk in the diets of children with an emphasis on total milk consumption, added sugars, and the shortfall nutrients of public health concern. Intake data from children 2 to 18 years participating in the NHANES 2001-2018 was used in the analyses. Data showed that consumers of flavored milk had higher total energy intake, total sugar intake and total added sugars compared to non-consumers. Intake of added sugars was higher among consumers of flavored milk compared to non-consumers, but consumers of flavored milk consumed approximately 1-cup equivalent more total milk compared to non-consumers. The increased milk consumption among consumers of flavored milk may in part explain the significantly higher intakes of vitamins A, D and B-12, riboflavin, calcium, potassium, magnesium and phosphorus than non-consumers. Based on data from this observational study, flavored milk contributes nutrients of public health concern in the diets of children. Objectives 2A, 2B and 2C aimed to assess the rural-urban differences in food security status and assess its association with food availability and participation in federal nutrition assistance programs among the different age groups of children. However, the data on rural-urban residence from NHANES are not freely available and are considered restricted use data. We did however receive approval from the Center for Disease Control and Prevention (CDC), National Center for Health Statistics (NCHS) Research Data Center (RDC) last year to access restricted data on rural-urban residence. We have now completed the data analysis in the RDC. The tables from the analyses have been submitted to the RDC for review/approval for this information to be used in publications (per NCHS-RDC regulations, the findings cannot be disclosed prior to obtaining the final approval). Subsequent to the approval, we will begin drafting manuscripts for submission. In the interim, we had previously received approval from the USDA, ARS to conduct two ancillary studies related to the COVID-19 pandemic. Our first study assessed the impact of COVID-19 on the overall operations of emergency food assistance organizations such as community food pantries. For this qualitative study, we recruited 18 food pantries in the Houston Metro Area and conducted staff interviews. These interviews inquired about their operations during the pandemic and any alterations thereof; including food procurement and distribution, safety measures taken, clientele served, assistance received/obtained, etc. We generated a publication from this study and have a second paper currently in preparation. Overall, our findings indicate that the food pantries developed diverse ways to cope with the increased demands of the pandemic. There were major changes that occurred in their operations including food procurement and distribution processes, safety measures undertaken, number of staff and volunteers, the clientele that was served (number and demographics) as well as in the funding/assistance they received. Our study also illustrated that there are several susceptibilities we must further research and seek to alter to effectively manage the next national food insecurity crisis. The second study is an online survey to assess the impact of COVID-19 on food access and food security in the state of Texas. The online survey was rolled out in May 2021 and closed May 2022. Currently, we are in the process of cleaning the data and subsequently the data will be analyzed. Objective 3 aimed to examine determinants of changes in standardize body mass index (BMI) during the school year and summer and the effectiveness of interventions to prevent accelerated summer weight gain. Researchers completed a systematic review and meta-analysis of interventions for obesity prevention and treatment among school-age children targeting the summer months when children are not in school, and assessing the interventions' impact on children's BMI, physical activity (PA), diet, sedentary behavior, and sleep. A total of 44 studies were identified for inclusion in the systematic review. Most identified studies targeted PA and diet. The majority of studies lacked rigor for inclusion in analyses. A total of five prevention interventions were meta-analyzed and we found that there was no evidence that the prevention interventions were associated with changes in children's BMI. There was no evidence that summertime obesity interventions targeting PA and dietary intake are effective in the prevention or treatment of obesity in children. We also conducted a re-examination of a dataset in which we followed a kindergarten cohort through the 5 years of elementary school to examine seasonality in children's height and weight gain separately and the contribution of seasonality in height and weight to patterns previously observed in standardized BMI. In addition, it has been hypothesized that the school year and summer environment results in changes in children's behaviors that affect their exposure to the light dark cycle causing potential circadian disruption during summer. Measuring changes in circadian physiology is extremely labor intensive and must be achieved under lab-based conditions, making it prohibitive to assess in larger samples. However, mathematical modeling approaches offer potential promise to be able to predict circadian parameters from wearable data. As a first step toward being able to analyze circadian parameters from wearable devices, we conducted a validation study using a secondary analysis of an existing dataset in which we compared the prediction of children's circadian phase using a physiologically informed mathematical model of circadian entrainment to the gold standard dim light melatonin onset measured in the lab. We found that the mathematical model could estimate children's circadian phase within 31 minutes of their measured dim light melatonin onset and provided more accurate estimates than sleep timing as assessed by wrist worn accelerometers. Finally using an existing nationally representative dataset called the Early Childhood Longitudinal Study (ECLS) in which evidence of accelerated summer weight gain has been previously observed, we have been investigating whether we can observe similar BMI trajectory groups like those identified in our local kindergarten cohort of 7,500+ children. Using the ECLS dataset, we have identified four BMI trajectory groups. While this is one fewer than we previously observed in our local sample, the overall pattern was very similar. Currently, we are working on a latent profile analysis of weight related behaviors. In the next year we will examine the association between the behavioral profiles and the BMI trajectory groups.


Accomplishments
1. Flavored milk is not a bad beverage choice. To help address the low intake of nutrients of public health concern, the 2020 Dietary Guidelines for Americans recommend 2.5 servings of dairy products for 4-8 years old children and 3 servings for 9-18 years old. Researchers at the Children's Nutrition Research Center in Houston, Texas, conducted a secondary data analysis to examine the nutritional contribution of flavored milk in the diets of children. The most notable results showed that consumers of flavored milk had higher intakes of total energy, total sugars, and total added sugars compared to non-consumers; however, the amount of added sugars contributed by flavored milk was minimal. Consumers of flavored milk consumed more total milk (approximately one cup more) than non-consumers and had significantly higher intakes of fiber, vitamins D, A and B-12, riboflavin, calcium, potassium, magnesium and phosphorus than non-consumers. Based on data from this study, flavored milk is not a bad beverage choice because the nutritional benefits of flavored milk far outweigh the added sugar content.

2. COVID-19 tremendously impacted Emergency Food Assistance Organizations' operations. With fewer volunteers and less person-to-person contact as well as a surge of Americans newly facing food insecurity during the COVID-19 pandemic, there was a tremendous shift in need and how the Emergency Food Assistance Organizations (EFAOs) operate. Researchers at the Children's Nutrition Research Center in Houston, Texas, conducted a study with the EFAOs that included food pantries and human service centers to assess the impact of COVID-19 on the EFAO’s overall operations. Our findings indicated that four major categories of change occurred due to COVID-19: new safety measures, changes in food distribution processes, changes in volunteerism and staffing, and changes in the amounts of food distributed. Our study helped identify and understand the tremendous social and economic challenges/changes incurred by the EFAOs in their operations (food procurement and distribution) to ensure food access to food insecure households, especially those with children. These findings can help inform policy makers and should be addressed to manage future emergency food insecurity crisis more effectively.

3. Participation in SNAP in addition to school meals does not improve diet quality among school aged children. Low-income households or individuals often rely on federal and community food and nutrition assistance programs to meet their dietary needs, and it is not unusual for eligible households to participate in more than one program. Two of the largest federal nutrition assistance programs administered by the Food and Nutrition Service of the USDA are the Supplemental Nutrition Assistance Program (SNAP, formerly the Food Stamp Program) and the School Meal Programs including National School Lunch Program (NSLP) and School Breakfast Program (SBP). Researchers at the Children's Nutrition Research Center in Houston, Texas, conducted a study to investigate the relationship between participation in school meals only and school meals plus SNAP combined and diet quality among a nationally representative sample of US children ages 5–18 years old. Results indicate that participation in school meals plus SNAP was not associated with higher overall diet quality compared to eligible non-participants or school meals only participants. More research is warranted to better understand the complex interplay between nutrition assistance program participation and diet quality for children from low-income families.

4. Children increase their height at a faster rate during school, but weight increases in a more consistent manner. Children have been shown to increase their body mass index (BMI) at a faster rate during summer compared to the school year, yet the extent to which height and weight gain follow this same pattern is unclear. Researchers at the Children's Nutrition Research Center in Houston, Texas, conducted a reanalysis of a dataset with measurement data for over 7,500 children during their five years of elementary school. We observed that children increased their height at a faster rate during the school year by about 0.05 cm per month compared to the summer, while weight gain remained more consistent. Because BMI is a value derived from the mass and height of an individual, the slower rate of height gain during summer combined with steady increases in weight contributed to the observed pattern of accelerated summer weight gain. Because rates of obesity increase during elementary school and weight increases in a consistent manner, these results suggest that children would benefit from obesity prevention efforts during both the school year and summer.

5. There is little evidence that summertime obesity prevention interventions are effective. Children increase their body mass index (BMI) at a faster rate during summer compared to the school year suggesting a need for intervention, yet little is known about the effectiveness of existing interventions aimed at the prevention and treatment of obesity during summer. Researchers at the Children's Nutrition Research Center in Houston, Texas, conducted a systematic review and identified 45 interventions designed to either prevent accelerated summer weight gain or help reduce BMI during summer among children who have an unhealthy weight status. Our research uncovered that many studies lacked the scientiifc rigor to be included in our meta-analysis. Our findings suggest that overall, many studies were ineffective at improving children's BMI during the summer. Researchers should improve their design (more frequent measures) and reporting of findings to aid in future meta-analyses and additional work is needed to determine how interventions can better impact children's weight status during summer.

6. Mathematical modeling can be used to accurately predict children's circadian phase. Measuring changes in circadian physiology in children is extremely labor- and time-intensive as children must undergo a lab protocol in which hourly saliva samples are collected 7 hours before bedtime and ending an hour past their bedtime under dim light conditions. To address this problem, researchers at the Children's Nutrition Research Center in Houston, Texas, leveraged mathematical modeling approaches in the prediction of circadian parameters using wearable data collection devices. In a study comparison of circadian phase as assessed in the lab and using wearable data collection devices processed through a mathematical model, we found that the mathematical model was able to predict circadian phase within 31 minutes of the lab assessed circadian phase. This represents a significant improvement in the ability to predict circadian phase using wearable data collection devices as similar studies in adults report prediction errors of an hour or more. Our innovation may lead to the development of personalized smart phone/wearable interventions to promote healthier sleep and circadian rhythms in children and the potential application of such interventions in the prevention of accelerated summer weight gain.