Measuring food availability and accessibility among adolescents: Moving beyond the neighbourhood boundary

A multi-dimensional access index: Exploring emergency food assistance in New York City

Access to resources and services needs to be considered from a multi-dimensional perspective to capture the complex landscape of human experience. The robust body of research exploring food access has multiple limitations that create an incomplete view of food access, like studies limited to only one mode of transit and inconsistent methods across studies which limit generalizability. This study proposes a framework to formulate a multi-dimensional access index that considers travel time, operating hours, and availability of transit infrastructure across space. We use food pantries in New York City as a case study since there are relatively few of them and they have limited opening hours. We propose an index that quantifies spatiotemporal access by different modes of transportation and takes operating hours of food pantries into account during a one week time period. We compare our results to two traditional access measures and demonstrate that our index provides a significantly different measure of access. We utilize this index to highlight areas of high need but low resources, which shows the importance of this tool to policy makers and service providers. We use our experience of developing this index to highlight the challenges with quantitative analysis of human experience. Our tool is reproducible through an open-access software, which allows researchers and policy-makers to utilize it with parameters that reflect their communities.

Associations between the neighbourhood food environment and food and drink purchasing in England during lockdown: A repeated cross-sectional analysis

INTRODUCTION

Evidence for the effect of neighbourhood food environment (NFE) exposures on diet in the UK is mixed, potentially due to exposure misclassification. This study used the first national COVID-19 lockdown in England as an opportunity to isolate the independent effects of the NFE exposure on food and drink purchasing, and assessed whether these varied by region.

METHODS

Transaction-level purchasing data for food and drink items for at-home (1,221 households) and out-of-home consumption (171 individuals) were available from the GB Kantar Fast Moving Consumer Goods Panel for London and the North of England. The study period included 23rd March to 10th May 2020 ('lockdown'), and the same period in 2019 for comparison. NFE exposures included food outlet density and proximity, and NFE composition within a 1 km network buffer around the home. Associations were estimated for both years separately, adjusted for individual and household characteristics, population density and area deprivation. Interaction terms between region and exposures were explored.

RESULTS

There were no consistent patterns of association between NFE exposures and food and drink purchasing in either time period. In 2019, there was some evidence for a 1.4% decrease in energy purchased from ultra-processed foods for each additional 500 m in the distance to the nearest OOH outlet (IR 0.986, 95% CI 0.977 to 0.995, p = 0.020). In 2020, there was some evidence for a 1.8% reduction in total take-home energy for each additional chain supermarket per km2 in the neighbourhood (IR 0.982, 95% CI 0.969, 0.995, p = 0.045). Region-specific effects were observed in 2019 only.

DISCUSSION

Findings suggest that the differences in exposure to the NFE may not explain differences in the patterns or healthiness of grocery purchasing. Observed pre-pandemic region-specific effects allude to the importance of geographical context when designing research and policy. Future research may assess associations for those who relied on their NFE during lockdown.

The Influence of the School Neighborhood Food Retail Environment on Unhealthy Food Purchasing Behaviors Among Adolescents: A Systematic Review

INTRODUCTION

Adolescents are often exposed to food retailers selling unhealthy food items during their lunch breaks and school commutes. This systematic review examines the influence of school neighborhood food retail environments on adolescent food purchasing.

METHODS

A systematic search of 6 databases. Observational studies published from January 2012 to December 2022 that measured food availability, accessibility, or exposure, measured food purchasing, and focused on adolescents (aged 10-19 years) were eligible for inclusion.

RESULTS

Twelve studies with 97 findings were included. Thirty-one findings indicated that a school neighborhood with a high density of unhealthy food retail, a school with unhealthy food retail nearby, or exposure to unhealthy food retail on the journey to/from school was associated with higher prevalence and frequency of unhealthy food purchases.

DISCUSSION

Adolescents' food purchasing behaviors may be meaningfully affected by their school neighborhood food retail environment; however, the included studies have many methodological shortcomings.

IMPLICATIONS FOR RESEARCH AND PRACTICE

Results identify the need for new studies that measure food purchasing, use comprehensive definitions of food retail environments, and adopt more rigorous methods to approximate exposure to food retail. More robust evidence would strengthen the rationale for policy or program interventions and potentially indicate specific targets for intervention.

Global positioning system-based food environment exposures, diet-related, and cardiometabolic health outcomes: a systematic review and research agenda

BACKGROUND

Geographic access to food may affect dietary choices and health outcomes, but the strength and direction of associations may depend on the operationalization of exposure measures. We aimed to systematically review the literature on up-to-date evidence on the association between food environment exposures based on Global Positioning System (GPS) and diet-related and cardiometabolic health outcomes.

METHODS

The databases PubMed, Embase.com, APA PsycInfo (via Ebsco), Cinahl (via Ebsco), the Web of Science Core Collection, Scopus, and the International Bibliography of the Social Sciences (via ProQuest) were searched from inception to October 31, 2022. We included studies that measured the activity space through GPS tracking data to identify exposure to food outlets and assessed associations with either diet-related or cardiometabolic health outcomes. Quality assessment was evaluated using the criteria from a modified version of the Newcastle-Ottawa Scale (NOS) for cross-sectional studies. We additionally used four items from a quality assessment tool to specifically assess the quality of GPS measurements.

RESULTS

Of 2949 studies retrieved, 14 studies fulfilled our inclusion criteria. They were heterogeneous and represent inconsistent evidence. Yet, three studies found associations between food outlets and food purchases, for example, more exposure to junk food outlets was associated with higher odds of junk food purchases. Two studies found associations between greater exposure to fast food outlets and higher fast food consumption and out of three studies that investigated food environment in relation to metabolic outcomes, two studies found that higher exposure to an unhealthy food environment was associated with higher odds of being overweight.

CONCLUSIONS

The current and limited evidence base does not provide strong evidence for consistent associations of GPS-based exposures of the food environment with diet-related and cardiometabolic health outcomes.

Systematic review of best practices for GPS data usage, processing, and linkage in health, exposure science and environmental context research

Global Positioning System (GPS) technology is increasingly used in health research to capture individual mobility and contextual and environmental exposures. However, the tools, techniques and decisions for using GPS data vary from study to study, making comparisons and reproducibility challenging.

OBJECTIVES

The objectives of this systematic review were to (1) identify best practices for GPS data collection and processing; (2) quantify reporting of best practices in published studies; and (3) discuss examples found in reviewed manuscripts that future researchers may employ for reporting GPS data usage, processing and linkage of GPS data in health studies.

DESIGN

A systematic review.

DATA SOURCES

Electronic databases searched (24 October 2023) were PubMed, Scopus and Web of Science (PROSPERO ID: CRD42022322166).

ELIGIBILITY CRITERIA

Included peer-reviewed studies published in English met at least one of the criteria: (1) protocols involving GPS for exposure/context and human health research purposes and containing empirical data; (2) linkage of GPS data to other data intended for research on contextual influences on health; (3) associations between GPS-measured mobility or exposures and health; (4) derived variable methods using GPS data in health research; or (5) comparison of GPS tracking with other methods (eg, travel diary).

DATA EXTRACTION AND SYNTHESIS

We examined 157 manuscripts for reporting of best practices including wear time, sampling frequency, data validity, noise/signal loss and data linkage to assess risk of bias.

RESULTS

We found that 6% of the studies did not disclose the GPS device model used, only 12.1% reported the per cent of GPS data lost by signal loss, only 15.7% reported the per cent of GPS data considered to be noise and only 68.2% reported the inclusion criteria for their data.

CONCLUSIONS

Our recommendations for reporting on GPS usage, processing and linkage may be transferrable to other geospatial devices, with the hope of promoting transparency and reproducibility in this research.

PROSPERO REGISTRATION NUMBER

CRD42022322166.

Influences of the community and consumer nutrition environment on the food purchases and dietary behaviors of adolescents: A systematic review

Adolescence is a period of increased autonomy over decision-making, including food choices, and increased exposure to influences outside the home, including the food environment. This review aims to synthesize the evidence for the influence of community nutrition environments, spatial access to food outlets, and consumer nutrition environments, environments inside food outlets, on adolescent food purchasing and dietary behaviors in high-income countries. Six databases were searched for articles published before January 2023. Results were synthesized using a vote-counting technique and effect direction plots that record the direction of the effect in relation to the anticipated relationship with health. Thirty-four observational and two intervention studies met the inclusion criteria. In the 13 studies assessing adolescent exposure to healthy community nutrition environments, results did not show clear associations with dietary and purchasing outcomes. Thirty studies assessed adolescents' exposure to unhealthy community nutrition environments with the majority (n = 17/30, 57%) reporting results showing that greater exposure to food outlets classified as unhealthy was associated with less healthy food purchases and dietary intakes. Inconsistent results were observed across the seven studies investigating associations with the consumer environment. Further research in these areas, including more high-quality intervention studies, may help to develop policy strategies to improve adolescents' dietary behaviors.

Selective Daily Mobility Bias in the Community Food Environment: Case Study of Greater Hartford, Connecticut

The community food environment has potential influences on community members' dietary health outcomes, such as obesity and Type II diabetes. However, most existing studies evaluating such health effects neglect human mobility. In food patrons' daily travels, certain locations may be preferred and patronized more frequently than others. This behavioral uncertainty, known as the selective daily mobility bias (SDMB), is less explored in community-food-environment research. In this paper, we aim to confirm the existence of the SDMB by systematically exploring the large-scale GPS-based restaurant-visit patterns in the Greater Harford region, Connecticut. Next, we explore the restaurant and neighborhood characteristics that are associated with the restaurant-visit patterns. Our primary results demonstrate that (1) most restaurant customers originate from areas outside of the census tract where the restaurant is located, and (2) restaurants located in socially vulnerable areas attract more customers in total, more customers from local areas, and more customers from other socially vulnerable areas. These results confirm the relevance of the SDMB to the community food environment, and suggest ways that the SDMB can be moderated by an uneven socio-economic landscape. The findings demonstrate the necessity of incorporating human-mobility data into the study of the community food environment.

Investigating how researcher-defined buffers and self-drawn neighbourhoods capture adolescent availability to physical activity facilities and greenspaces: An exploratory study

BACKGROUND

Modifying the environment is considered an effective population-level approach for increasing healthy behaviours, but associations remain ambiguous. This exploratory study aims to compare researcher-defined buffers and self-drawn neighbourhoods (SDN) to objectively measured availability of physical activity (PA) facilities and greenspaces in adolescents.

METHODS

Seven consecutive days of GPS data were collected in an adolescent sample of 14-18 year olds (n = 69). Using Points of Interest and greenspace data, availability of PA opportunities within activity spaces were determined. We compared 30 different definitions of researcher-defined neighbourhoods and SDNs to objectively measured availability.

RESULTS

Findings showed low agreement for all researcher-defined buffers in measuring the availability of PA facilities in activity spaces. However, results were less clear for greenspace. SDNs also demonstrate low agreement for capturing availability to the PA environment.

CONCLUSION

This exploratory study highlights the inadequacy of researcher-defined buffers and SDNs to define availability to environmental features.

An Analysis of Food Accessibility of Mountain Cities in China: A Case Study of Chongqing

Mountain cities are characterized by undulating terrain, complex road networks, and diverse road facilities, which makes accessing food more difficult than in cities with a flat terrain. This study proposes an enhanced two-step method based on the Baidu map service for the construction of supermarket–market–retail food sales architecture and for calculating food accessibility. The accessibility indices of seven major food categories (grains and oils, fruits, vegetables, seafood, meat, milk, and eggs) were calculated considering the principle of the fairest walking routes in Chongqing. The correlations between food accessibility and house price and house age in Chongqing were explored through local Moran’s analysis and geographically weighted regression. The correlations illustrated the fairness of the distribution of food accessibility in Chongqing among the poor and rich. The experiments showed generally well-developed food accessibility in the main urban areas of Chongqing. However, accessibility to fresh fruits and vegetables lagged in newly built urban areas.

Neighbourhood food typologies, fast food outlet visitation and snack food purchasing among adolescents in Melbourne, Australia

OBJECTIVE

Despite the increased attention on neighbourhood food environments and dietary behaviours, studies focusing on adolescents are limited. This study aims to characterise typologies of food environments surrounding adolescents and their associations with fast food outlet visitation and snack food purchasing to/from school.

DESIGN

The number of food outlets (supermarket; green grocers; butcher/seafood/deli; bakeries; convenience stores; fast food/takeaways; café and restaurants) within a 1 km buffer from home was determined using a Geographic Information System. Adolescents' self-reported frequency of fast food outlet visitation and snack food purchasing to/from school. Latent Profile Analysis was conducted to identify typologies of the food environment. Cross-sectional multilevel logistic regression analyses were conducted to examine the relationships between food typologies, fast food outlet visitations and snack food purchasing to/from school.

SETTING

Melbourne, Australia.

PARTICIPANTS

Totally, 410 adolescents (mean age= 15·5 (sd = 1·5) years).

RESULTS

Four distinct typologies of food outlets were identified: (1) limited variety/low number; (2) some variety/low number; (3) high variety/medium number and (4) high variety/high number. Adolescents living in Typologies 1 and 2 had three times higher odds of visiting fast food outlets ≥1 per week (Typology 1: OR = 3·71, 95 % CI 1·23, 11·19; Typology 2: OR = 3·65, 95 % CI 1·21, 10·99) than those living in Typology 4. No evidence of association was found between typologies of the food environments and snack food purchasing behaviour to/from school among adolescents.

CONCLUSION

Local government could emphasise an overall balance of food outlets when designing neighbourhoods to reduce propensity for fast food outlet visitation among adolescents.

Measuring Cluster-Based Spatial Access to Shopping Stores under Real-Time Travel Time

Shopping stores are an important part of retail facilities and indispensable public facilities in a city. They are not only concentrated in shopping malls, but also distributed independently throughout the city, and often agglomerated in space. This paper attempts to measure the rationality of the spatial layout of all shopping stores in the city. Residents will visit multiple shopping stores in one trip to meet their demands. Based on this characteristic, this paper studies shopping store clusters and proposes a cluster two-step floating catchment area (C-2SFCA) method to analyze the accessibility differences of shopping stores in urban areas. Using the case of Beijing within the Fifth Ring Road, this paper implements the C-2SFCA method in a study unit of traffic analysis zones (TAZ) considering three transport modes (car, public transport, walking) with the support of real-time travel time collected from an internet map. The results show that spatial accessibility differed greatly under different transport modes and also had an uneven distribution pattern. Among these three results, the spatial variation of public transport accessibility was the highest. The results can provide references for urban planners in facility configuration and decision-making.

Consumers' Perceptions of Healthy Food Availability in Online Food Delivery Applications (OFD Apps) and Its Association With Food Choices Among Public University Students in Malaysia

This retrospective cross-sectional study was conducted to study consumers' perceptions of healthy food availability in online food delivery applications (OFD apps) among public university students in Malaysia and its association with their food choices. A total of 290 subjects aged 19–29 years old were recruited from 20 public universities in Malaysia via snowball sampling. Data was collected through an online questionnaire which consisted of socio-demographic status, use of OFD apps (most frequently used brand, usage frequency, food choice, and expenditure per transaction), factors affecting food choice in OFD apps, consumers' perceptions of healthy food availability in OFD apps and recommendation for improvements. The most frequently used apps among the subjects was Food Panda (46.6%), however, majority of the subjects in this study (41.4%) rarely used OFD apps. Also, most of the subjects ordered unhealthy food (77.6%) and spent up to RM15–RM19 for each transaction (43.1%). There was no significant difference between the use of OFD apps and gender (p > 0.05). Among the five food choice motives, “price and convenience” motive was the most influencing food choice factor in OFD apps. Majority of the subjects (76.9%) had a negative perception of healthy food availability (variety, price, and quality of healthy food) in OFD apps. No significant association was found between consumers' perceptions of healthy food availability in OFD apps and their food choices made in OFD apps among the subjects in this study (p > 0.05). Also, majority (85.9%) responded they are keen to purchase healthy foods through OFD apps if they are given an option. However, most Malaysian public university students perceived that there were not much variety of healthy food, of good quality and affordable price, available in OFD apps. This finding suggests that the online food environment in Malaysia are perceived as unhealthy. Future studies can explore the online food environment particularly its impact on community health and well-being. Public health professionals and policymakers need to address the online food environment issues as part of the obesogenic food environment in Malaysia especially when OFD is one of the most convenient service in this country.

Density of Fast Food Outlets around Educational Facilities in Riyadh, Saudi Arabia: Geospatial Analysis

BACKGROUND

Childhood obesity remains a public health issue globally. The latest estimate from the World Health Organization showed that over 340 million children and adolescents aged 5-19 were overweight or obese in 2016.

OBJECTIVE

Our study aimed to assess the density of fast food outlets around educational facilities in Riyadh, Saudi Arabia.

METHODS

We employed geospatial and quantitative analyses using data on fast food outlets (from surveys conducted between November 2019 and May 2020) and educational facilities in Riyadh city. Data analyses conducted using ArcMap 10.6 and Stata 15 compared the density within 500 m and 500-1000 m from the facilities.

RESULTS

We found a high density of fast food outlets around educational facilities. Nearly 80% of fast food were within twelve-minute walking or five-minute driving distances from schools, and nearly 70% of all educational facilities had at least one fast food outlet within the buffer. We also found the densities were high within both the areas closer and the areas farther away from educational facilities. In addition, the density was significantly higher around private schools compared to government schools, and the density around girls-only schools and both-gender schools was higher than that around boys-only schools.

CONCLUSION

There is a high density of fast food outlets around educational facilities in Saudi Arabia. Effective policies are needed to help reduce potential exposure to fast food among young people in Saudi Arabia and other countries with similar settings.

Associations between specific components of executive control and eating behaviors in adolescence: A study using objective and subjective measures

A growing literature suggests that executive control (EC; also known as "executive functioning" or "EF") in adolescence may play an important role in the development of key health behaviors, including eating behaviors. However, existing literature has significant limitations in the conceptualization and measurement of EC. The current study aims to address these limitations by employing a multidimensional approach to conceptualizing and measuring adolescent EC, including both objective and subjective measures covering multiple components of EC, and examining links with specific eating behaviors. A community sample of adolescents (N = 208; mean age = 14.5 years) completed a battery of performance-based neuropsychological tasks assessing specific components of EC (i.e., working memory, inhibitory control, flexible shifting), a norm-referenced questionnaire covering problems with specific components of EC in daily life, and a measure assessing key eating behaviors (i.e., uncontrolled eating, emotional eating, cognitive restraint). Objectively-measured adolescent working memory was significantly and uniquely associated with cognitive restraint, with stronger working memory associated with less cognitive restraint. No other associations between performance-based EC tasks and eating behaviors were found. In contrast, using subjective reports of EC, problems with inhibitory control were associated with greater uncontrolled eating, and problems with flexible shifting were associated with greater emotional eating. The results suggest links between specific aspects of EC and specific eating behaviors in adolescence, as well as the potential importance of context for understanding the role of EC in eating behavior. Given evidence that EC is modifiable, the findings have potential implications for novel interventions addressing eating behaviors by targeting EC.

An activity space approach to understanding how food access is associated with dietary intake and BMI among urban, low-income African American women

Inconclusive evidence for how food environments affect health may result from an emphasis on residential neighborhood-based measures of exposure. We used an activity space approach to examine whether 1) measures of food access and 2) associations with diet and BMI differ between residential and activity space food environments among low-income African American women in Atlanta, Georgia (n = 199). Although residential and activity space environments differed across all dimensions of food access, being located farther away from 'unhealthy' outlets was associated with lower BMI in both environments. Future research should move beyond asking whether residential and activity space environments differ, toward examining if, how, and under what conditions these differences impact the estimation of health effects.

Evaluating Spatial Accessibility to General Hospitals with Navigation and Social Media Location Data: A Case Study in Nanjing

Spatial accessibility to general hospitals is an important indicator of the convenience and ability of residents to obtain medical services. Therefore, developing a model for measuring accessibility to general hospitals by multiple transportation modes is necessary. In this study, considering that the increase in travel time will reduce the attractiveness of general hospitals, we used the Two-Step Floating Catchment Area with the Gaussian attenuation function, in which the supply was presented by capacity of hospitals (i.e., number of beds), and the demand was presented by population in each grid derived with social media data mapping real-time locations of active users. The Gaussian Two-Step Floating Catchment Area (Ga2SFCA) simulates the attenuation tendency of the general hospital service capabilities over transit time. To obtain a highly precise understanding of accessibility to hospitals, transit time on Baidu Maps' navigation service was used as the impedance condition, and the study area was divided into 1 square kilometer grids as the basic unit of research. Taking Nanjing city as a case study, it is found that the accessibility distribution shape changes from a multi-centered circular pattern to a multi-peak distribution, as the time threshold increases. By comparing the accessibility among 11 districts varying from main urban area to suburbs, the accessibility to general hospitals in Nanjing is significantly regionally unbalanced in both travel modes. By calculating and mapping the Modal Accessibility Gap (MAG) of the two travel modes, different modes of transportation resulted in different general hospital accessibility distributions. Generally, private car is superior in access to general hospitals to public transit in most areas. In the central area, public traffic may not contribute to the access to medical services as much as we thought, rather it plays a role in areas far from hospitals along metro lines and bus routes.

SmokingOpp: Detecting the Smoking 'Opportunity' Context Using Mobile Sensors

Context plays a key role in impulsive adverse behaviors such as fights, suicide attempts, binge-drinking, and smoking lapse. Several contexts dissuade such behaviors, but some may trigger adverse impulsive behaviors. We define these latter contexts as 'opportunity' contexts, as their passive detection from sensors can be used to deliver context-sensitive interventions. In this paper, we define the general concept of 'opportunity' contexts and apply it to the case of smoking cessation. We operationalize the smoking 'opportunity' context, using self-reported smoking allowance and cigarette availability. We show its clinical utility by establishing its association with smoking occurrences using Granger causality. Next, we mine several informative features from GPS traces, including the novel location context of smoking spots, to develop the SmokingOpp model for automatically detecting the smoking 'opportunity' context. Finally, we train and evaluate the SmokingOpp model using 15 million GPS points and 3,432 self-reports from 90 newly abstinent smokers in a smoking cessation study.

Is accessibility in the eye of the beholder? Social inequalities in spatial accessibility to health-related resources in Montréal, Canada

Neighbourhood resources are often considered to be spatially accessible to people when they are located close to their place of residence, a perspective which overlooks individuals' unique lived experience of their neighbourhood and how they define it. Drawing on the relational approach to place and on Sen's capability approach, we explore spatial accessibility to health-related resources, and the social gradient therein, in light of people's place experiences. Using data from 1101 young adults from Montreal (Canada) who participated in the Interdisciplinary Study of Inequalities in Smoking (ISIS), we compare the social gradients in the presence of health-related resources located (i) within uniform areas (defined as circular buffers and road-network buffers) around participants' place of residence; and (ii) within participants' self-defined neighbourhoods. Social inequalities in accessibility to a diversity of health-related resources (grocery stores, fruit and vegetable stores, eating and drinking places, recreational sports centres, civic, social, and fraternal organizations, bike paths, parks, social services, libraries, dental offices, physician offices) were more pronounced in self-defined neighbourhoods than in uniform buffer areas. Neglecting the variability in people's place experiences may distort the assessment of social inequalities in accessibility, and ultimately, of neighbourhood effects on health inequalities.

Mobile Sensing in Environmental Health and Neighborhood Research

Public health research has witnessed a rapid development in the use of location, environmental, behavioral, and biophysical sensors that provide high-resolution objective time-stamped data. This burgeoning field is stimulated by the development of novel multisensor devices that collect data for an increasing number of channels and algorithms that predict relevant dimensions from one or several data channels. Global positioning system (GPS) tracking, which enables geographic momentary assessment, permits researchers to assess multiplace personal exposure areas and the algorithm-based identification of trips and places visited, eventually validated and complemented using a GPS-based mobility survey. These methods open a new space-time perspective that considers the full dynamic of residential and nonresidential momentary exposures; spatially and temporally disaggregates the behavioral and health outcomes, thus replacing them in their immediate environmental context; investigates complex time sequences; explores the interplay among individual, environmental, and situational predictors; performs life-segment analyses considering infraindividual statistical units using case-crossover models; and derives recommendations for just-in-time interventions.

A Mentor-Led Text-Messaging Intervention Increases Intake of Fruits and Vegetables and Goal Setting for Healthier Dietary Consumption among Rural Adolescents in Kentucky and North Carolina, 2017

Introduction—Text-messaging interventions hold promise for successful weight loss interventions. However, there is limited research on text-messaging interventions to improve dietary intake among rural adolescents, who are at greater risk for obesity and related risk factors. The goal of this study was to test an eight-week, mentor-led text-messaging intervention among 14–16-year-old rural adolescents: the “Go Big and Bring It Home” Project to improve fruit and vegetable and healthy beverage intake. Methods and Materials—Eight rural high schools in eastern Kentucky and eastern North Carolina participated (n = 4 were randomized as intervention schools and n = 4 were randomized as control schools). Adolescents were recruited to participate in the eight-week text-messaging intervention. The text messages were primarily affective messages, and included a weekly challenge related to consuming fruits, vegetables, or healthy/low-calorie beverages. Undergraduate nutrition students sent text messages on Tuesday and Saturday every week over the eight-week period via the “Group Me” mobile application. Delayed controls received no information or text messages during the eight-week intervention. Fruit and vegetable intake was measured with the National Cancer Institute Fruit and Vegetable screener and beverage intake was assessed using the Beverage Questionnaire-10 (BEVQ-10). Intention-to-treat analyses were conducted among all those that completed the baseline and post-intervention survey (n = 277 intervention students and n = 134 delayed control students). All linear regression models were adjusted for race and were clustered on school to control for intraclass correlation. Results—In adjusted analyses, there was a statistically significant positive intervention effect on the primary outcome of fruit and vegetable servings/day with a mean difference between intervention and control participants of 1.28 servings/day (95% Confidence Interval 1.11, 1.48). There was no intervention effect on beverage intake. There was a statistically significant increase in the odds of goal setting for healthier dietary behaviors among intervention participants relative to controls. Conclusion—An eight-week text-messaging intervention led to increases in self-reported fruit and vegetable intake and improvements in goal setting for healthier dietary behaviors. Due to the use of undergraduate students to deliver the messages, and use of an existing web application, this text-messaging intervention can be sustained in underserved, rural environments. Thus there is potential for significant reach and public health impact to improve dietary patterns.

Comparing the Data Quality of Global Positioning System Devices and Mobile Phones for Assessing Relationships Between Place, Mobility, and Health: Field Study

Background

Mobile devices are increasingly used to collect location-based information from individuals about their physical activities, dietary intake, environmental exposures, and mental well-being. Such research, which typically uses wearable devices or mobile phones to track location, benefits from the growing availability of fine-grained data regarding human mobility. However, little is known about the comparative geospatial accuracy of such devices.

Objective

In this study, we compared the data quality of location information collected from two mobile devices that determine location in different ways—a global positioning system (GPS) watch and a mobile phone with Google’s Location History feature enabled.

Methods

A total of 21 chronically ill participants carried both devices, which generated digital traces of locations, for 28 days. A mobile phone–based brief ecological momentary assessment (EMA) survey asked participants to manually report their location at 4 random times throughout each day. Participants also took part in qualitative interviews and completed surveys twice during the study period in which they reviewed recent mobile phone and watch trace data to compare the devices’ trace data with their memory of their activities on those days. Trace data from the devices were compared on the basis of (1) missing data days, (2) reasons for missing data, (3) distance between the route data collected for matching day and the associated EMA survey locations, and (4) activity space total area and density surfaces.

Results

The watch resulted in a much higher proportion of missing data days (P<.001), with missing data explained by technical differences between the devices as well as participant behaviors. The mobile phone was significantly more accurate in detecting home locations (P=.004) and marginally more accurate (P=.07) for all types of locations combined. The watch data resulted in a smaller activity space area and more accurately recorded outdoor travel and recreation.

Conclusions

The most suitable mobile device for location-based health research depends on the particular study objectives. Furthermore, data generated from mobile devices, such as GPS phones and smartwatches, require careful analysis to ensure quality and completeness. Studies that seek precise measurement of outdoor activity and travel, such as measuring outdoor physical activity or exposure to localized environmental hazards, would benefit from the use of GPS devices. Conversely, studies that aim to account for time within buildings at home or work, or those that document visits to particular places (such as supermarkets, medical facilities, or fast food restaurants), would benefit from the greater precision demonstrated by the mobile phone in recording indoor activities.

Food environments and dietary intakes among adults: does the type of spatial exposure measurement matter? A systematic review

BACKGROUND

The relationships between food environments and dietary intake have been assessed via a range of methodologically diverse measures of spatial exposure to food outlets, resulting in a largely inconclusive body of evidence, limiting informed policy intervention.

OBJECTIVE

This systematic review aims to evaluate the influence of methodological choice on study outcomes by examining the within-study effect of availability (e.g., counts) versus accessibility (e.g., proximity) spatial exposure measures on associations with diet.

METHODS

(PROSPERO registration: CRD42018085250). PubMed, Web of Science, Scopus and ScienceDirect databases were searched for empirical studies from 1980 to 2017, in the English language, involving adults and reporting on the statistical association between a dietary outcome and spatial exposure measures of both availability and accessibility. Studies were appraised using an eight-point quality criteria with a narrative synthesis of results.

RESULTS

A total of 205 associations and 44 relationships (i.e., multiple measures of spatial exposure relating to a particular food outlet type and dietary outcome) were extracted from 14 eligible articles. Comparative measures were dominated by counts (availability) and proximity (accessibility). Few studies compared more complex measures and all counts were derived from place-based measures of exposure. Sixteen of the 44 relationships had a significant effect involving an availability measure whilst only 8 had a significant effect from an accessibility measure. The largest effect sizes in relationships were mostly for availability measures. After stratification by scale, availability measure had the greatest effect size in 139 of the 176 pairwise comparisons. Of the 33% (68/205) of associations that reached significance, 53/68 (78%) were from availability measures. There was no relationship between study quality and reported study outcomes.

CONCLUSIONS

The limited evidence suggests that availability measures may produce significant and greater effect sizes than accessibility measures. However, both availability and accessibility measures may be important concepts of spatial exposure depending on the food outlet type and dietary outcome examined. More studies reporting on multi-method effects are required to differentiate findings by the type of spatial exposure assessment and build an evidence base regarding the appropriateness and robustness of measures under different circumstances.

Using Individual GPS Trajectories to Explore Foodscape Exposure: A Case Study in Beijing Metropolitan Area

With the growing interest in studying the characteristics of people’s access to the food environment and its influence upon individual health, there has been a focus on assessing individual food exposure based on GPS trajectories. However, existing studies have largely focused on the overall activity space using short-period trajectories, which ignores the complexity of human movements and the heterogeneity of the spaces that are experienced by the individual over daily life schedules. In this study, we propose a novel framework to extract the exposure areas consisting of the localized activity spaces around daily life centers and non-motorized commuting routes from long-term GPS trajectories. The newly proposed framework is individual-specific and can incorporate the internal heterogeneity of individual activities (spatial extent, stay duration, and timing) in different places as well as the dynamics of the context. A pilot study of the GeoLife dataset suggests that there are significant variations in the magnitude as well as the composition of the food environment in different parts of the individual exposure area, and residential environment is not representative of the overall foodscape exposure.

User acceptance of location-tracking technologies in health research: Implications for study design and data quality

Research regarding place and health has undergone a revolution due to the availability of consumer-focused location-tracking devices that reveal fine-grained details of human mobility. Such research requires that participants accept such devices enough to use them in their daily lives. There is a need for a theoretically grounded understanding of acceptance of different location-tracking technology options, and its research implications. Guided by an extended Unified Theory of Acceptance and Use of Technology (UTAUT), we conducted a 28-day field study comparing 21 chronically ill people's acceptance of two leading, consumer-focused location-tracking technologies deployed for research purposes: (1) a location-enabled smartphone, and (2) a GPS watch/activity tracker. Participants used both, and completed two surveys and qualitative interviews. Findings revealed that all participants exerted effort to facilitate data capture, such as by incorporating devices into daily routines and developing workarounds to keep devices functioning. Nevertheless, the smartphone was perceived to be significantly easier and posed fewer usability challenges for participants than the watch. Older participants found the watch significantly more difficult to use. For both devices, effort expectancy was significantly associated with future willingness to participate in research although prosocial motivations overcame some concerns. Social influence, performance expectancy and use behavior were significantly associated with intentions to use the devices in participants' personal lives. Data gathered via the smartphone was significantly more complete than data gathered via the watch, primarily due to usability challenges. To make longer-term participation in location tracking research a reality, and to achieve complete data capture, researchers must minimize the effort involved in participation; this requires usable devices. For long-term location-tracking studies using similar devices, findings indicate that only smartphone-based tracking is up to the challenge.

Opportunities and Challenges for Environmental Exposure Assessment in Population-Based Studies

A growing number and increasing diversity of factors are available for epidemiological studies. These measures provide new avenues for discovery and prevention, yet they also raise many challenges for adoption in epidemiological investigations. Here, we evaluate 1) designs to investigate diseases that consider heterogeneous and multidimensional indicators of exposure and behavior, 2) the implementation of numerous methods to capture indicators of exposure, and 3) the analytical methods required for discovery and validation. We find that case-control studies have provided insights into genetic susceptibility but are insufficient for characterizing complex effects of environmental factors on disease development. Prospective and two-phase designs are required but must balance extended data collection with follow-up of study participants. We discuss innovations in assessments including the microbiome; mass spectrometry and metabolomics; behavioral assessment; dietary, physical activity, and occupational exposure assessment; air pollution monitoring; and global positioning and individual sensors. We claim the the availability of extensive correlated data raises new challenges in disentangling specific exposures that influence cancer risk from among extensive and often correlated exposures. In conclusion, new high-dimensional exposure assessments offer many new opportunities for environmental assessment in cancer development. Cancer Epidemiol Biomarkers Prev; 26(9); 1370-80. ©2017 AACR.

You are where you live: Methodological challenges to measuring children's exposure to hazards

Many of the challenges that affect children living in poverty are directly related to the neighborhoods in which they live. Places that inhibit healthy living and those that expose children to environmental pollution tend to more heavily affect children in poverty. This environmental injustice is a natural concern of the fields of urban planning, geography, and children's health. Yet many decisions that affect opportunities for healthy living are made without a full understanding of how neighborhood context influences such opportunities. In this brief, we paint inequalities in child health outcomes as a spatial problem, review some of the geospatial tools used by urban planners and geographers, discuss common reasons for misclassification or misrepresentation of spatially explicit problems, and propose more suitable methods for measuring opportunities and exposures germane to the field of child poverty. Throughout, we emphasize the need for evidence-driven, spatially grounded responses to child poverty issues with a spatial dimension.

Using Agent-Based Models to Develop Public Policy about Food Behaviours: Future Directions and Recommendations

Most adults are overweight or obese in many western countries. Several population-level interventions on the physical, economical, political, or sociocultural environment have thus attempted to achieve a healthier weight. These interventions have involved different weight-related behaviours, such as food behaviours. Agent-based models (ABMs) have the potential to help policymakers evaluate food behaviour interventions from a systems perspective. However, fully realizing this potential involves a complex procedure starting with obtaining and analyzing data to populate the model and eventually identifying more efficient cross-sectoral policies. Current procedures for ABMs of food behaviours are mostly rooted in one technique, often ignore the food environment beyond home and work, and underutilize rich datasets. In this paper, we address some of these limitations to better support policymakers through two contributions. First, via a scoping review, we highlight readily available datasets and techniques to deal with these limitations independently. Second, we propose a three steps' process to tackle all limitations together and discuss its use to develop future models for food behaviours. We acknowledge that this integrated process is a leap forward in ABMs. However, this long-term objective is well-worth addressing as it can generate robust findings to effectively inform the design of food behaviour interventions.

Where do people purchase food? A novel approach to investigating food purchasing locations

Background

Studies exploring associations between food environments and food purchasing behaviours have been limited by the absence of data on where food purchases occur. Determining where food purchases occur relative to home and how these locations differ by individual, neighbourhood and trip characteristics is an important step to better understanding the association between food environments and food behaviours.

Methods

Conducted in Melbourne, Australia, this study recruited participants within sixteen neighbourhoods that were selected based on their socioeconomic characteristics and proximity to supermarkets. The survey material contained a short questionnaire on individual and household characteristics and a food purchasing diary. Participants were asked to record details related to all food purchases made over a 2-week period including food store address. Fifty-six participants recorded a total of 952 food purchases of which 893 were considered valid for analysis. Households and food purchase locations were geocoded and the network distance between these calculated. Linear mixed models were used to determine associations between individual, neighbourhood, and trip characteristics and distance to each food purchase location from home. Additional analysis was conducted limiting the outcome to: (a) purchase made when home was the prior origin (n. 484); and (b) purchases made within supermarkets (n. 317).

Results

Food purchases occurred a median distance of 3.6 km (IQR 1.8, 7.2) from participants’ homes. This distance was similar when home was reported as the origin (median 3.4 km; IQR 1.6, 6.4) whilst it was shorter for purchases made within supermarkets (median 2.8 km; IQR 1.6, 5.6). For all purchases, the reported food purchase location was further from home amongst the youngest age group (compared to the oldest age group), when workplace was the origin of the food purchase trip (compared to home), and on weekends (compared to weekdays). Differences were also observed by neighbourhood characteristics.

Conclusions

This study has demonstrated that many food purchases occur outside what is traditionally considered the residential neighbourhood food environment. To better understand the role of food environments on food purchasing behaviours, further work is needed to develop more appropriate food environment exposure measures.

Electronic supplementary material

The online version of this article (doi:10.1186/s12942-017-0082-z) contains supplementary material, which is available to authorized users.

Measures of the food environment: A systematic review of the field, 2007-2015

BACKGROUND

Many studies have examined the relationship between the food environment and health-related outcomes, but fewer consider the integrity of measures used to assess the food environment. The present review builds on and makes comparisons with a previous review examining food environment measures and expands the previous review to include a more in depth examination of reliability and validity of measures and study designs employed.

METHODS

We conducted a systematic review of studies measuring the food environment published between 2007 and 2015. We identified these articles through: PubMed, Embase, Web of Science, PsycINFO, and Global Health databases; tables of contents of relevant journals; and the National Cancer Institute's Measures of the Food Environment website. This search yielded 11,928 citations. We retained and abstracted data from 432 studies.

RESULTS

The most common methodology used to study the food environment was geographic analysis (65% of articles) and the domination of this methodology has persisted since the last review. Only 25.9% of studies in this review reported the reliability of measures and 28.2% reported validity, but this was an improvement as compared to the earlier review. Very few of the studies reported construct validity. Studies reporting measures of the school or worksite environment have decreased since the previous review. Only 13.9% of the studies used a longitudinal design.

CONCLUSIONS

To strengthen research examining the relationship between the food environment and population health, there is a need for robust and psychometrically-sound measures and more sophisticated study designs.

Between exposure, access and use: Reconsidering foodscape influences on dietary behaviours

Good accessibility to both healthy and unhealthy food outlets is a greater reality than food deserts. Yet, there is a lack of conceptual insights on the contextual factors that push individuals to opt for healthy or unhealthy food outlets when both options are accessible. Our comprehension of foodscape influences on dietary behaviours would benefit from a better understanding of the decision-making process for food outlet choices. In this paper, we build on the fundamental position that outlet choices are conditioned by how much outlets' attributes accommodate individuals' constraints and preferences. We further argue that food outlets continuously experienced within individuals' daily-path help people re-evaluate food acquisition possibilities, push them to form intentions, and shape their preferences for the choices they will subsequently make. Doing so, we suggest differentiating access, defined as the potential for the foodscape to be used at the time when individuals decide to do so, from exposure, which acts as a constant catalyst for knowledge, intention, preferences and routine tendency. We conclude with implications for future research, and discuss consequences for public policy.

How can GPS technology help us better understand exposure to the food environment? A systematic review

Purpose

Global Positioning Systems (GPS) are increasingly being used to objectively assess movement patterns of people related to health behaviours. However research detailing their application to the food environment is scarce. This systematic review examines the application of GPS in studies of exposure to food environments and their potential influences on health.

Methods

Based on an initial scoping exercise, published articles to be included in the systematic review were identified from four electronic databases and reference lists and were appraised and analysed, the final cut-off date for inclusion being January 2015. Included studies used GPS to identify location of individuals in relation to food outlets and link that to health or diet outcomes. They were appraised against a set of quality criteria.

Results

Six studies met the inclusion criteria, which were appraised to be of moderate quality. Newer studies had a higher quality score. Associations between observed mobility patterns in the food environment and diet related outcomes were equivocal. Findings agreed that traditional food exposure measures overestimate the importance of the home food environment.

Conclusions

The use of GPS to measure exposure to the food environment is still in its infancy yet holds much potential. There are considerable variations and challenges in developing and standardising the methods used to assess exposure.

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Since 2011 just 6 studies have been published employing GPS to quantify exposure to food environments.

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The studies were generally only of moderate quality.

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There were significant variations and challenges in the methods and techniques used.

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GIS neighbourhoods may not well represent food environment exposures based on GPS data.

Obesity, diet quality, physical activity, and the built environment: the need for behavioral pathways

BACKGROUND

The built environment (BE) is said to influence local obesity rates. Few studies have explored causal pathways between home-neighborhood BE variables and health outcomes such as obesity. Such pathways are likely to involve both physical activity and diet.

METHODS

The Seattle Obesity Study (SOS II) was a longitudinal cohort of 440 adult residents of King Co, WA. Home addresses were geocoded. Home-neighborhood BE measures were framed as counts and densities of food sources and physical activity locations. Tax parcel property values were obtained from County tax assessor. Healthy Eating Index (HEI 2010) scores were constructed using data from food frequency questionnaires. Physical activity (PA) was obtained by self-report. Weights and heights were measured at baseline and following 12 months' exposure. Multivariable regressions examined the associations among BE measures at baseline, health behaviors (HEI-2010 and physical activity) at baseline, and health outcome both cross-sectionally and longitudinally.

RESULTS

None of the conventional neighborhood BE metrics were associated either with diet quality, or with meeting PA guidelines. Only higher property values did predict better diets and more physical activity. Better diets and more physical activity were associated with lower obesity prevalence at baseline and 12 mo, but did not predict weight change.

CONCLUSION

Any links between the BE and health outcomes critically depend on establishing appropriate behavioral pathways. In this study, home-centric BE measures, were not related to physical activity or to diet. Further studies will need to consider a broader range of BE attributes that may be related to diets and health.

Population-Level Measures to Predict Obesity Burden in Public Schools: Looking Upstream for Midstream Actions

PURPOSE

To estimate school-level obesity burden, as reflected in prevalence of obesity, based on the characteristics of students' socioeconomic and geographic environments.

DESIGN

Secondary analysis of cross-sectional data.

SETTING

Public schools (N = 504) from 43 of 67 counties in Pennsylvania.

PARTICIPANTS

Kindergarten through grade 12 students (N = 255 949).

MEASURES

School-level obesity prevalence for the year 2014 was calculated from state-mandated student body mass index (BMI) measurements. Eighteen aggregate variables, characterizing schools and counties, were retrieved from federal data sources.

ANALYSIS

Three classification variables-excess weight (BMI ≥ 85th percentile), obesity (BMI ≥ 95th percentile), and severe obesity (BMI > 35% or 120% of 95th percentile)-each with 3 groups of schools (low-, average-, and high-prevalence) were created for discriminant function analysis, based on state mean and standard deviation of school distribution. Analysis tested each classification model to reveal school- and county-level dimensions on which school groups differed from each other.

RESULTS

Discriminant functions for obesity, which contained school enrollment, percentage of students receiving free/reduced-price lunch, percentage of black/Hispanic students, school location (suburban/other), percentage of county adults with postsecondary education, and percentage of county adults with obesity, yielded 67.86% correct classification (highest accuracy), compared to 34.23% schools classified by chance alone.

CONCLUSION

In the absence of mandated student BMI screenings, the model developed in this study can be used to identify schools most likely to have high obesity burden and, thereafter, determine dissemination of enhanced resources for the implementation of proven prevention policies and programs.

Self-regulation interventions to reduce consumption of sugar-sweetened beverages in adolescents

This study evaluated the efficacy of self-regulation interventions through the use of drink-specific implementation intentions and drink-specific Go/No-Go training tasks as compensatory strategies to modify inhibitory control to reduce intake of sugar-sweetened beverages (SSB). In a between-subjects randomized manipulation of implementation intentions and Go/No-Go training to learn to inhibit sugary drink consumption, 168 adolescents reporting inhibitory control problems over sugary drinks and foods were recruited from high schools in southern California to participate. Analysis of covariance overall test of effects revealed no significant differences between the groups regarding calories consumed, calories from SSBs, grams of sugar consumed from drinks, or the number of unhealthy drinks chosen. However, subsequent contrasts revealed SSB implementation intentions significantly reduced SSB consumption following intervention while controlling for inhibitory control failure and general SSB consumption during observation in a lab setting that provided SSBs and healthy drinks, as well as healthy and unhealthy snacks. Specifically, during post-intervention observation, participants in the sugar-sweetened beverage implementation intentions (SSB-II) conditions consumed significantly fewer calories overall, fewer calories from drinks, and fewer grams of sugar. No effects were found for the drink-specific Go/No-Go training on SSB or calorie consumption. However, participants in SSB-II with an added SSB Go/No-Go training made fewer unhealthy drink choices than those in the other conditions. Implementation intentions may aid individuals with inhibitory (executive control) difficulties by intervening on pre-potent behavioral tendencies, like SSB consumption.

Using GPS and activity tracking to reveal the influence of adolescents' food environment exposure on junk food purchasing

OBJECTIVES

This study examines the influence of adolescents' exposure to unhealthy food outlets on junk food purchasing during trips between home and school, with particular attention to how exposure and purchasing differ according to child's biological sex, mode of transportation, and direction to or from school.

METHODS

Between 2010 and 2013, students (n = 654) aged 9-13 years from 25 schools in London and Middlesex County, ON, completed a socio-demographic survey and an activity diary (to identify food purchases), and were observed via a global positioning system for 2 weeks (to track routes for trips to/from school). Spatial data on routes and purchase data were integrated with a validated food outlet database in a geographic information system, and exposure was measured as the minutes a child spent within 50 m of an unhealthy food outlet (i.e., fast food restaurants, variety stores). For trips involving junk food exposure (n = 4588), multilevel logistic regression was used to assess the relationship between exposure and purchasing.

RESULTS

Multilevel analyses indicated that adolescents' duration of exposure to unhealthy food outlets between home and school had a significant effect on the likelihood of junk food purchasing. This relationship remained significant when the data were stratified by sex (female/male), trip direction (to/from school) and travel mode (active/car), with the exception of adolescents who travelled by bus.

CONCLUSION

Policies and programs that mitigate the concentration of unhealthy food outlets close to schools are critical for encouraging healthy eating behaviours among children and reducing diet-related health issues such as obesity.

"Socioeconomic inequalities in children's accessibility to food retailing: Examining the roles of mobility and time"

Childhood overweight and obesity rates in Canada are at concerning levels, more apparently so for individuals of lower socioeconomic status (SES). Accessibility to food establishments likely influences patterns of food consumption, a contributor to body weight. Previous work has found that households living in lower income neighbourhoods tend to have greater geographical accessibility to unhealthy food establishments and lower accessibility to healthy food stores. This study contributes to the literature on neighbourhood inequalities in accessibility to healthy foods by explicitly focusing on children, an understudied population, and by incorporating mobility and time into metrics of accessibility. Accessibility to both healthy and unhealthy food retailing is measured within children's activity spaces using Road Network and Activity Location Buffering methods. Weekday vs. weekend accessibility to food establishments is then compared. The results suggest that children attending lower SES schools had almost two times the density of fast food establishments and marginally higher supermarket densities in their activity spaces. Children attending higher SES schools also had much larger activity spaces. All children had higher supermarket densities during weekdays than on weekend days.

Comparing children's GPS tracks with geospatial proxies for exposure to junk food

Various geospatial techniques have been employed to estimate children's exposure to environmental cardiometabolic risk factors, including junk food. But many studies uncritically rely on exposure proxies which differ greatly from actual exposure. Misrepresentation of exposure by researchers could lead to poor decisions and ineffective policymaking. This study conducts a GIS-based analysis of GPS tracks--'activity spaces'--and 21 proxies for activity spaces (e.g. buffers, container approaches) for a sample of 526 children (ages 9-14) in London, Ontario, Canada. These measures are combined with a validated food environment database (including fast food and convenience stores) to create a series of junk food exposure estimates and quantify the errors resulting from use of different proxy methods. Results indicate that exposure proxies consistently underestimate exposure to junk foods by as much as 68%. This underestimation is important to policy development because children are exposed to more junk food than estimated using typical methods.