Professional Education

  • Bachelor of Science, University of California Berkeley (2007)
  • Master of Public Health, University of California Berkeley (2011)
  • Doctor of Philosophy, University of California Berkeley (2016)

Stanford Advisors

All Publications

  • A Focused Review of Smartphone Diet-Tracking Apps: Usability, Functionality, Coherence With Behavior Change Theory, and Comparative Validity of Nutrient Intake and Energy Estimates. JMIR mHealth and uHealth Ferrara, G., Kim, J., Lin, S., Hua, J., Seto, E. 2019; 7 (5): e9232


    BACKGROUND: Smartphone diet-tracking apps may help individuals lose weight, manage chronic conditions, and understand dietary patterns; however, the usabilities and functionalities of these apps have not been well studied.OBJECTIVE: The aim of this study was to review the usability of current iPhone operating system (iOS) and Android diet-tracking apps, the degree to which app features align with behavior change constructs, and to assess variations between apps in nutrient coding.METHODS: The top 7 diet-tracking apps were identified from the iOS iTunes and Android Play online stores, downloaded and used over a 2-week period. Each app was independently scored by researchers using the System Usability Scale (SUS), and features were compared with the domains in an integrated behavior change theory framework: the Theoretical Domains Framework. An estimated 3-day food diary was completed using each app, and food items were entered into the United States Department of Agriculture (USDA) Food Composition Databases to evaluate their differences in nutrient data against the USDA reference.RESULTS: Of the apps that were reviewed, LifeSum had the highest average SUS score of 89.2, whereas MyDietCoach had the lowest SUS score of 46.7. Some variations in features were noted between Android and iOS versions of the same apps, mainly for MyDietCoach, which affected the SUS score. App features varied considerably, yet all of the apps had features consistent with Beliefs about Capabilities and thus have the potential to promote self-efficacy by helping individuals track their diet and progress toward goals. None of the apps allowed for tracking of emotional factors that may be associated with diet patterns. The presence of behavior change domain features tended to be weakly correlated with greater usability, with R2 ranging from 0 to .396. The exception to this was features related to the Reinforcement domain, which were correlated with less usability. Comparing the apps with the USDA reference for a 3-day diet, the average differences were 1.4% for calories, 1.0% for carbohydrates, 10.4% for protein, and -6.5% for fat.CONCLUSIONS: Almost all reviewed diet-tracking apps scored well with respect to usability, used a variety of behavior change constructs, and accurately coded calories and carbohydrates, allowing them to play a potential role in dietary intervention studies.

    View details for DOI 10.2196/mhealth.9232

    View details for PubMedID 31102369

  • Enhancing safe routes to school programs through community-engaged citizen science: two pilot investigations in lower density areas of Santa Clara County, California, USA. BMC public health Rodriguez, N. M., Arce, A., Kawaguchi, A., Hua, J., Broderick, B., Winter, S. J., King, A. C. 2019; 19 (1): 256


    BACKGROUND: While promoting active commuting to school can positively affect children's daily physical activity levels, effectively engaging community members to maximize program impact remains challenging. We evaluated the initial utility of adding a technology-enabled citizen science engagement model, called Our Voice, to a standard Safe Routes to School (SRTS) program to enhance program engagement activities and student travel mode behavior.METHODS: In Investigation 1, a prospective controlled comparison design was used to compare the initial year of the Santa Clara County Public Health Department's SRTS program, with and without the Our Voice engagement model added, in two elementary schools in Gilroy, California, USA. School parents served as Our Voice citizen scientists in the SRTS + Our Voice school. In Investigation 2, the feasibility of the combined SRTS + Our Voice methods was evaluated in a middle school in the same district using students, rather than adults, as citizen scientists. Standard SRTS program engagement measures and student travel mode tallies were collected at the beginning and end of the school year for each school.RESULTS: In the elementary school investigation (Investigation 1), the SRTS + Our Voice elementary school held twice as many first-year SRTS planning/encouragement events compared to the SRTS-Alone elementary school, and between-school changes in walking/biking to school rates favored the SRTS + Our Voice school (increases of 24.5% vs. 2.6%, P<.001). The Investigation 2 results supported the feasibility of using students to conduct SRTS + Our Voice in a middle school-age population.CONCLUSIONS: The findings from this first-generation study indicated that adding a technology-enabled citizen science process to a standard elementary school SRTS program was associated with higher levels of community engagement and walking/biking to school compared to SRTS alone. The approach was also found to be acceptable and feasible in a middle school setting.

    View details for PubMedID 30823917

  • How Well Do Seniors Estimate Distance to Food? The Accuracy of Older Adults' Reported Proximity to Local Grocery Stores. Geriatrics (Basel, Switzerland) Chrisinger, B. W., King, A. C., Hua, J., Saelens, B. E., Frank, L. D., Conway, T. L., Cain, K. L., Sallis, J. F. 2019; 4 (1)


    (1) Background: Findings from observational studies of relations between neighborhood environments and health outcomes underscore the importance of both objective and perceived experiences of those environments. A clearer understanding of the factors associated with discrepancies between these two assessment approaches is needed to tailor public health interventions to specific populations. This study examined how individual and neighborhood characteristics affect perceptions of supermarket distance, particularly when perceptions do not match objective measures. (2) Methods: Participants were older adults (n = 880) participating in the Senior Neighborhood Quality of Life Study in the Seattle/King County, WA or Baltimore/Washington, DC regions. Two main analyses were conducted. The primary outcome for Analysis I was participants' geographic information systems (GIS)-based objective network distance to the closest supermarket. Generalized linear mixed models with block group-level random effects were used to assess associations between objective supermarket distance and individual/neighborhood characteristics. The primary outcome for Analysis II was a categorical "accuracy" variable, based on participants' perceived distance to the nearest supermarket/grocery store relative to the objective distance, assuming a walking speed of 1.0 m/s. Multivariate log-linear models fit neural networks were used to assess influential covariates. (3) Results: Several significant associations with objective distance to the nearest supermarket were observed, including a negative relationship with body mass index (BMI) (95% CI = -45.56, -0.23), having walked to the supermarket in the last 30 days (-174.86, -59.42), living in a high-walkability neighborhood, and residing in Seattle/King County (-707.69, -353.22). In terms of participants' distance accuracy, 29% were classified as accurate, 33.9% were "Underestimators", 24.0% "Overestimators", and 13.2% responded "Don't Know". Compared to Accurate participants, Overestimators were significantly less likely to have walked to the supermarket in the last 30 days, and lived objectively closer to a supermarket; Underestimators perceived significantly higher pedestrian safety and lived objectively further from a supermarket; and Don't Know were more likely to be women, older, not living independently, and not having recently walked to the supermarket. (4) Conclusions: Both modifiable and nonmodifiable factors influence the accuracy of older adults' perceptions of their proximity to the nearest supermarket. Recent experience in walking to the closest supermarket, along with personal safety, represent potentially modifiable perceived environmental factors that were related to older adults' accuracy of perceptions of their neighborhood food environment.

    View details for PubMedID 31023979

  • Maximizing the promise of citizen science to advance health and prevent disease. Preventive medicine King, A. C., Winter, S. J., Chrisinger, B. W., Hua, J., Banchoff, A. W. 2018

    View details for PubMedID 30593793

  • A Comprehensive Review of Arsenic Exposure and Risk from Rice and a Risk Assessment among a Cohort of Adolescents in Kunming, China. International journal of environmental research and public health Liao, N., Seto, E., Eskenazi, B., Wang, M., Li, Y., Hua, J. 2018; 15 (10)


    Inorganic arsenic (iAs) is carcinogenic and highly concentrated in rice. Dietary exposure to iAs is concerning among adolescents due to their developmental stage and iAs's long-latency effects. This paper aimed to assess iAs exposure from rice and related lifetime cancer risks (LCR) among adolescents in Kunming, China. A comprehensive literature review of iAs levels in rice and LCR in humans was also conducted. Average daily consumption of rice (ADC) was estimated from 267 adolescents (15⁻18 years). Rice samples obtained from 6 markets were analyzed for iAs concentration (AC). Estimated daily intake (EDI) of iAs was calculated using ADC, AC, and average body weight (BW). Lifetime Cancer Risk (LCR) was calculated using EDI and U.S. EPA derived iAs oral slope factor. The AC was 0.058 mg/kg and the average BW and ADC were 67.5 kg and 410 g/day for males and 55.5 kg and 337 g/day for females. The EDI and LCR were 3.52 * 10-4 mg/kg-BW/day and 5.28 * 10-4 for both males and females, with LCR 5 times above the U.S. LCR upper limit of 1.0 * 10-4. While the AC was below the Chinese maximum contaminant level of 0.2 mg/kg, study results indicated that Kunming adolescents may be at increased risk for iAs-related cancers.

    View details for PubMedID 30297612

  • Acceptability of smartphone-based assessments of physical activity and diet among a cohort of adolescents in Kunming, China Hua, J., Eom, S., Li, Y., Wang, M., Seto, E. HUMAN KINETICS PUBL INC. 2018: S244
  • Building activity-promoting environments that support health across the lifecourse through global citizen science research King, A., Banchoff, A., Winter, S., Hua, J., Dueaas, O., Dagan, A., Aguilar-Farias, N., Stathi, A. HUMAN KINETICS PUBL INC. 2018: S88
  • Models of Individual Dietary Behavior Based on Smartphone Data: The Influence of Routine, Physical Activity, Emotion, and Food Environment. PloS one Seto, E., Hua, J., Wu, L., Shia, V., Eom, S., Wang, M., Li, Y. 2016; 11 (4): e0153085


    Smartphone applications (apps) facilitate the collection of data on multiple aspects of behavior that are useful for characterizing baseline patterns and for monitoring progress in interventions aimed at promoting healthier lifestyles. Individual-based models can be used to examine whether behavior, such as diet, corresponds to certain typological patterns. The objectives of this paper are to demonstrate individual-based modeling methods relevant to a person's eating behavior, and the value of such approach compared to typical regression models.Using a mobile app, 2 weeks of physical activity and ecological momentary assessment (EMA) data, and 6 days of diet data were collected from 12 university students recruited from a university in Kunming, a rapidly developing city in southwest China. Phone GPS data were collected for the entire 2-week period, from which exposure to various food environments along each subject's activity space was determined. Physical activity was measured using phone accelerometry. Mobile phone EMA was used to assess self-reported emotion/feelings. The portion size of meals and food groups was determined from voice-annotated videos of meals. Individual-based regression models were used to characterize subjects as following one of 4 diet typologies: those with a routine portion sizes determined by time of day, those with portion sizes that balance physical activity (energy balance), those with portion sizes influenced by emotion, and those with portion sizes associated with food environments.Ample compliance with the phone-based behavioral assessment was observed for all participants. Across all individuals, 868 consumed food items were recorded, with fruits, grains and dairy foods dominating the portion sizes. On average, 218 hours of accelerometry and 35 EMA responses were recorded for each participant. For some subjects, the routine model was able to explain up to 47% of the variation in portion sizes, and the energy balance model was able to explain over 88% of the variation in portion sizes. Across all our subjects, the food environment was an important predictor of eating patterns. Generally, grouping all subjects into a pooled model performed worse than modeling each individual separately.A typological modeling approach was useful in understanding individual dietary behaviors in our cohort. This approach may be applicable to the study of other human behaviors, particularly those that collect repeated measures on individuals, and those involving smartphone-based behavioral measurement.

    View details for DOI 10.1371/journal.pone.0153085

    View details for PubMedID 27049852

    View details for PubMedCentralID PMC4822823

  • Acceptability and feasibility of smartphone-assisted 24 h recalls in the Chinese population. Public health nutrition Zang, J., Song, J., Wang, Z., Yao, C., Ma, J., Huang, C., Zhu, Z., Smith, L. P., Du, S., Hua, J., Seto, E., Popkin, B. M., Zou, S. 2015; 18 (18): 3272–77


    To examine the acceptability and feasibility of using smartphone technology to assess beverage intake and evaluate whether the feasibility of smartphone use is greater among key sub-populations.An acceptability and feasibility study of recording the video dietary record, the acceptability of the ecological momentary assessment (EMA), wearing smartphones and whether the videos helped participants recall intake after a cross-over validation study.Rural and urban area in Shanghai, China.Healthy adults (n 110) aged 20-40 years old.Most participants reported that the phone was acceptable in most aspects, including that videos were easy to use (70%), helped with recalls (77%), EMA reminders helped them record intake (75%) and apps were easy to understand (85%). However, 49% of the participants reported that they had trouble remembering to take videos of the beverages before consumption or 46% felt embarrassed taking videos in front of others. Moreover, 72% reported that the EMA reminders affected their consumption. When assessing overall acceptability of using smartphones, 72% of the participants were favourable responders. There were no statistically significant differences in overall acceptability for overweight v. normal-weight participants or for rural v. urban residents. However, we did find that the overall acceptability was higher for males (81%) than females (61%, P=0·017).Our study did not find smartphone technology helped with dietary assessments in a Chinese population. However, simpler approaches, such as using photographs instead of videos, may be more feasible for enhancing 24 h dietary recalls.

    View details for DOI 10.1017/S1368980015000907

    View details for PubMedID 25857612

    View details for PubMedCentralID PMC4600407

  • The Kunming CalFit study: modeling dietary behavioral patterns using smartphone data. Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference Seto, E., Hua, J., Wu, L., Bestick, A., Shia, V., Eom, S., Han, J., Wang, M., Li, Y. 2014; 2014: 6884–87


    Human behavioral interventions aimed at improving health can benefit from objective wearable sensor data and mathematical models. Smartphone-based sensing is particularly practical for monitoring behavioral patterns because smartphones are fairly common, are carried by individuals throughout their daily lives, offer a variety of sensing modalities, and can facilitate various forms of user feedback for intervention studies. We describe our findings from a smartphone-based study, in which an Android-based application we developed called CalFit was used to collect information related to young adults' dietary behaviors. In addition to monitoring dietary patterns, we were interested in understanding contextual factors related to when and where an individual eats, as well as how their dietary intake relates to physical activity (which creates energy demand) and psychosocial stress. 12 participants were asked to use CalFit to record videos of their meals over two 1-week periods, which were translated into nutrient intake by trained dietitians. During this same period, triaxial accelerometry was used to assess each subject's energy expenditure, and GPS was used to record time-location patterns. Ecological momentary assessment was also used to prompt subjects to respond to questions on their phone about their psychological state. The GPS data were processed through a web service we developed called Foodscoremap that is based on the Google Places API to characterize food environments that subjects were exposed to, which may explain and influence dietary patterns. Furthermore, we describe a modeling framework that incorporates all of these information to dynamically infer behavioral patterns that may be used for future intervention studies.

    View details for DOI 10.1109/EMBC.2014.6945210

    View details for PubMedID 25571578

  • Development and validity of a 3-day smartphone assisted 24-hour recall to assess beverage consumption in a Chinese population: a randomized cross-over study. Asia Pacific journal of clinical nutrition Smith, L. P., Hua, J., Seto, E., Du, S., Zang, J., Zou, S., Popkin, B. M., Mendez, M. A. 2014; 23 (4): 678–90


    This paper addresses the need for diet assessment methods that capture the rapidly changing beverage consumption patterns in China. The objective of this study was to develop a 3-day smartphone-assisted 24-hour recall to improve the quantification of beverage intake amongst young Chinese adults (n=110) and validate, in a small subset (n=34), the extent to which the written record and smartphone-assisted recalls adequately estimated total fluid intake, using 24-hour urine samples. The smartphone-assisted method showed improved validity compared with the written record-assisted method, when comparing reported total fluid intake to total urine volume. However, participants reported consuming fewer beverages on the smartphone-assisted method compared with the written record-assisted method, primarily due to decreased consumption of traditional zero-energy beverages (i.e. water, tea) in the smartphone-assisted method. It is unclear why participants reported fewer beverages in the smartphone-assisted method than the written record -assisted method. One possibility is that participants found the smartphone method too cumbersome, and responded by decreasing beverage intake. These results suggest that smartphone-assisted 24-hour recalls perform comparably but do not appear to substantially improve beverage quantification compared with the current written record-based approach. In addition, we piloted a beverage screener to identify consumers of episodically consumed SSBs. As expected, a substantially higher proportion of consumers reported consuming SSBs on the beverage screener compared with either recall type, suggesting that a beverage screener may be useful in characterizing consumption of episodically consumed beverages in China's dynamic food and beverage landscape.

    View details for DOI 10.6133/apjcn.2014.23.4.10

    View details for PubMedID 25516327

    View details for PubMedCentralID PMC4270062

  • Development and evaluation of a food environment survey in three urban environments of Kunming, China. BMC public health Hua, J., Seto, E., Li, Y., Wang, M. C. 2014; 14: 235


    Given the rapid pace of urbanization and Westernization and the increasing prevalence of obesity, there is a need for research to better understand the influence of the built environment on overweight and obesity in world's developing regions. Culturally-specific food environment survey instruments are important tools for studying changing food availability and pricing. Here, we present findings from an effort to develop and evaluate food environment survey instruments for use in a rapidly developing city in southwest China.We developed two survey instruments (for stores and restaurants), each designed to be completed within 10 minutes. Two pairs of researchers surveyed a pre-selected 1-km stretch of street in each of three socio-demographically different neighborhoods to assess inter-rater reliability. Construct validity was assessed by comparing the food environments of the neighborhoods to cross-sectional height and weight data obtained on 575 adolescents in the corresponding regions of the city.273 food establishments (163 restaurants and 110 stores) were surveyed. Sit-down, take-out, and fast food restaurants accounted for 40%, 21% and 19% of all restaurants surveyed. Tobacco and alcohol shops, convenience stores and supermarkets accounted for 25%, 12% and 11%, respectively, of all stores surveyed. We found a high percentage of agreement between teams (>75%) for all categorical variables with moderate kappa scores (0.4-0.6), and no statistically significant differences between teams for any of the continuous variables. More developed inner city neighborhoods had a higher number of fast food restaurants and convenience stores than surrounding neighborhoods. Adolescents who lived in the more developed inner neighborhoods also had a higher percentage of overweight, indicating well-founded construct validity. Depending on the cutoff used, 19% to 36% of male and 10% to 22% of female 16-year old adolescents were found to be overweight.The prevalence of overweight Chinese adolescents, and the food environments they are exposed to, deserve immediate attention. To our knowledge, these are the first food environment surveys developed specifically to assess changing food availability, accessibility, and pricing in China. These instruments may be useful in future systematic longitudinal assessments of the changing food environment and its health impact in China.

    View details for DOI 10.1186/1471-2458-14-235

    View details for PubMedID 24602326

    View details for PubMedCentralID PMC4016521

  • No evidence of an association between transient HIV viremia ("Blips") and lower adherence to the antiretroviral medication regimen. The Journal of infectious diseases Miller, L. G., Golin, C. E., Liu, H., Hays, R. D., Hua, J., Wenger, N. S., Kaplan, A. H. 2004; 189 (8): 1487–96


    Transient human immunodeficiency virus (HIV) viremia, a common phenomenon among patients taking antiretroviral therapy, is often attributed to lapses in adherence to the medication regimen. We investigated this relationship in a prospective observational cohort of 128 patients initiating a new regimen.A case of transient viremia was defined as an HIV RNA level of 40-1000 copies/mL ("blip") sandwiched between 2 months of HIV RNA levels <40 copies/mL ("pre" and "post"). Adherence was most often measured with a composite adherence score (CAS), which is primarily based on electronically measured adherence. Case subjects' adherence and dose-timing was compared with (1) that of other patients (control subjects), who had undetectable virus loads for 3 consecutive months, and (2) that during periods of sustained undetectable virus loads among the case subjects themselves, if available.Among the 28 case subjects, mean CAS-measured adherence did not decrease before transient viremia; adherence during the pre, blip, and post periods were 86%, 84%, and 80%, respectively. Control subjects had lower adherence levels during the corresponding 3 months (77%, 79%, and 75%, respectively; P = .046). Among the 19 patients able to serve as their own controls, CAS-measured adherence was higher during the period of transient viremia than during control periods (P = .01). Similar relationships were found when comparing only electronically measured adherence on a week-wise basis. There were no significant differences in dose-timing error between case subjects and control subjects.We found no evidence that transient HIV viremia is associated with decreases in adherence or differences in dose-timing. Other etiologies for transient viremia should be evaluated.

    View details for DOI 10.1086/382895

    View details for PubMedID 15073687