Metabolomics focuses on the study of metabolic changes occurring in varioussystems and utilizes quantitative and semi-quantitative measurements of multiple metabolites in parallel. Mass spectrometry (MS) is the most ubiquitous platform in this field, as it provides superior sensitivity regarding measurements of complex metabolic profiles in biological systems. When combined with MS, multivariate statistics and advanced machine learning algorithms provide myriad opportunities for bioinformatics insights beyond simple univariate data comparisons. In this dissertation, the application of MS-based metabolomics is introduced with an emphasis on biomarker discovery for human disease detection. To advance disease diagnosis using MS-based metabolomics, numerous statistical techniques have been implemented in this research including principal component analysis, factor analysis, partial least squares-discriminant analysis (PLS-DA), orthogonal PLS-DA, random forest, receiver operating characteristic analysis, as well as functional pathway/enzyme enrichment analyses. These approaches are highly useful for improving classification sensitivity and specificity related to disease-induced biological variation and can help identify useful biomarkers and potential therapeutic targets. It is also shown that MS-based metabolomics can distinguish between clinical and prodromal disease as well as similar diseases with related symptoms, which may assist in clinical staging and differential diagnosis, respectively. Additionally, MS-based metabolomics is shown to be promising for the early and accurate detection of diseases, thereby improving patient outcomes, and advancing clinical care. Herein, the application of MS methods and chemometric statistics to the diagnosis of breast cancer, coccidioidomycosis (Valley fever), and senile dementia (Alzheimer's disease) are presented and discussed. In addition to presenting original research, previous efforts in biomarker discovery will be synthesized and appraised. A Comment will be offered regarding the state of the science, specifically addressing the inefficient model of repetitive biomarker discovery and the need for increased translational efforts necessary to consolidate metabolomics findings and formalize purported metabolic markers as laboratory developed tests. Various factors impeding the translational throughput of metabolomics findings will be carefully considered with respect to study design, statistical analysis, and regulation of biomedical diagnostics. Importantly, this dissertation will offer critical insights to advance metabolomics from a scientific field to a practical one including targeted detection, enhanced quantitation, and direct-to-consumer considerations.

Background: Sugars form advanced glycation end products (AGEs) throughnatural metabolism and interactions with proteins, lipids, and nucleic acids, which accumulate in tissues and have been implicated in the etiology of chronic diseases. Due to the increased consumption of fructose and its high ability to form AGEs, a further understanding of this association is important to clarify the role of sugars in disease. The objective was to explore the association between usual fructose intake and serum levels of AGEs, as measured by carboxymethyl-lysine (CML) and methylglyoxal derivative (MG-H1), in healthy adults. Methods: This is a secondary analysis of a 15-d controlled feeding study (n=100) with participants consuming their usual diet conducted in the Phoenix metropolitan area. To assess participants’ usual diet, they were asked to complete two 7-d food diaries, which were then used to create custom 15-d menu plans administered during the feeding period. Forty participants were selected based on their 15-d mean total fructose intake for this analysis [top and bottom 20% of the sample distribution (median, IQR); high fructose (HF) n= 20, 72.6 (66.1-90.4) g/day, low fructose (LF) n= 20, 28.8 (22.7-32.2) g/day. Fasting serum collected five weeks after the feeding period were analyzed for CML and MG-H1, two well-established AGEs, using ELISA kits. A database of 549 common foods with known CML amounts was used to calculate exogenous CML intake based on daily food intake data. A general linear model was fitted to investigate the difference in serum CML and MG-H1 between LF and HF groups while adjusting for age, gender, BMI, and exogenous CML intake. Results: Participants in the HF group had significantly higher serum CML and lower MG-H1 levels compared to participants in the LF group (p=0.013 and p=0.002, respectively). This difference remained statistically significant after adjusting for covariates. Conclusions: The findings suggest that endogenous CML formation may be an explanation for the significantly higher serum CML levels in the HF compared to the LF group. This is significant in further understanding mechanisms of fructose intake and disease etiology and could have implications for at-risk populations consuming a high fructose diet.

Background: Understanding determinants of high consumption of sugar-sweetened beverages (SSBs), a highly prevalent obesogenic behavior, will help build effective customized public health interventions.

Objective: Our aim was to identify child and parent lifestyle and household demographic factors predictive of high SSB consumption frequency in children from low-income, ethnically diverse communities that may help inform public health interventions.

Design: We used a cross-sectional telephone household survey.

Participants/setting: Participants were 717 boys and 686 girls aged 3 to 18 years old from the New Jersey Childhood Obesity Study living in five low-income cities (Camden, New Brunswick, Newark, Trenton, and Vineland). The adult most knowledgeable about household food shopping completed a questionnaire over the telephone inquiring about their and their child's dietary and physical activity habits, and household-, parent-, and child-level demographics.

Main outcome measures: Child's SSB consumption frequency was measured.

Statistical analysis performed: Multivariate ordered logit models were designed to investigate a variety of variables hypothesized to affect the frequency of SSB consumption. Exploratory stratified analyses by race, sex, and age were also conducted.

Results: Eight percent of our study participants never consumed SSBs, 45% consumed SSBs at least once per day, and 23% consumed twice or more per day. SSB consumption was higher among children 12 to 18 years vs 3 to 5 years (P<0.0001), of non-Hispanic black vs non-Hispanic white race/ethnicity (P=0.010), who were moderate fast food consumers vs never consumers (P=0.003), and those whose parents were high vs low SSB consumers (P<0.0001). Living in a non-English-speaking household (P=0.030), having a parent with a college or higher education vs less than high school (P=0.003), and having breakfast 6 to 7 days/wk vs never to 2 days/wk or less were associated with lower SSB consumption (P=0.001).

Conclusions: We identified a number of household-, parent-, and child-level predictors of SSB consumption, which varied by race, sex, and age, useful for building customized interventions targeting certain behaviors in ethnically diverse, low-income children.

Background

The United States Department of Agriculture’s Supplemental Nutrition Assistance Program (SNAP) is the country’s largest nutrition assistance program for low-income populations. Although SNAP has been shown to reduce food insecurity, research findings on the diet quality of program participants are inconsistent.

Objective

This study evaluated whether the community food environment is a potential moderator of the association between SNAP participation and eating behaviors.

Design

This cross-sectional study used participant data from a telephone survey of 2,211 households in four cities in New Jersey. Data were collected from two cross-sectional panels from 2009 to 2010 and 2014. Food outlet data were purchased from commercial sources and classified as supermarkets, small grocery stores, convenience stores, or limited service restaurants.

Participants/setting

Analysis is limited to 983 respondents (588 SNAP participants) with household incomes below 130% of the federal poverty level.

Main outcome measures

Eating behaviors were assessed as frequency of consumption of fruit, vegetables, salad, and sugar-sweetened beverages.

Statistical analyses performed

Interaction and stratified analyses using gamma regression determined the differences in the association between SNAP participation and eating behaviors by the presence or absence of food outlets adjusted for covariates.

Results

SNAP participation was associated with a higher frequency of consuming sugar-sweetened beverages (P<0.05) when respondents lived within ¼ to ½ mile of a small grocery store, supermarket, and limited service restaurant. SNAP participants who did not live close to a convenience store reported a lower frequency of sugar-sweetened beverage consumption (P=0.01), and those living more than ½ mile away from a supermarket reported a lower frequency of fruit consumption (P=0.03).

Conclusions

The findings from this study suggest that the community food environment may play a role in moderating the association between SNAP participation and eating behaviors. Although SNAP participation is associated with some unhealthy behaviors, this association may only hold true when respondents live in certain food environments.

Background

Participation in the Special Supplemental Nutrition Assistance Program for Women, Infants, and Children (WIC) among 0- to 5-year-old children is associated with healthier diets. Extension of dietary benefits to older, age-ineligible children (5-18 years old) residing in WIC households has not been fully investigated.

Objective

Examine the association between household WIC participation and dietary behaviors of age-ineligible children.

Design

Cross-sectional secondary analysis of data collected from 2 independent panels (2009-2010 and 2014) of the New Jersey Child Health Study, using household surveys. Questions derived from national surveys assessed consumption frequency of specific foods among 5- to 18-year-old children.

Participants/setting

The analytic sample included 616 age-ineligible children from households with incomes below 200% of the federal poverty level, 398 of whom were from WIC-participating households.

Main outcome measures

Eating behaviors were measured as frequency of daily consumption of fruit, vegetables, 100% juice, sugar-sweetened beverages, and sweet and salty snacks.

Statistical analysis

Multivariable negative binomial models examined the association between eating behaviors and household WIC participation status adjusting for child’s age, sex, and race; mother’s education; city of residence; household size; and panel. Results are expressed as incidence rate ratios (IRRs).

Results

Household WIC participation was not associated with dietary behaviors among age-ineligible children (5-18 years old) in the overall sample. However, healthier dietary patterns were observed for specific demographic groups. Compared with age-ineligible children in non-WIC households, age-ineligible children in WIC households had (1) a higher frequency of vegetable consumption among 12- to 18-year-old children (IRR = 1.29; 95% confidence interval [CI] 1.05-1.58; P = .015); (2) a marginally significant higher frequency of 100% juice consumption among females (IRR = 1.27; 95% CI 1.00-1.62; P = .053); and (3) a lower frequency of sugar-sweetened beverages consumption among Hispanic children (IRR = 0.61; 95% CI 0.43-0.86; P = .004).

Conclusions

Household WIC participation may positively influence dietary behaviors of age-ineligible children, suggesting a possible WIC spillover effect. Revisions to WIC package composition should consider the possible dietary implications for all children in the household.

Urinary sucrose and fructose has been suggested as a predictive biomarker of total sugars intake based on research involving UK adults. The purpose of this study was to determine the association between total sugars consumption and 24-hour urinary sucrose and fructose (24uSF) in US adult population and to investigate the effect of physical activity on this association. Fifty seven free-living healthy subjects 20 to 68 years old, participated in a 15-day highly controlled feeding study, consuming their habitual diet, provided by the research metabolic kitchen. Dietary sugars were estimated using Nutrition Data System for Research (NDSR). Subjects collected eight 24-hour urine samples measured for urinary sucrose and fructose. Physical activity was assessed daily using a validated 15-day log that inquired about 38 physical activities across six domains; home activities, transportation, occupation, conditioning, sports and leisure. The mean total sugars intake and added sugars intake of the sample was 112.2 (33.1) g/day and 65.8 (29.0) g/day (9.7%EI), respectively. Significant moderate positive correlation was found between 15-d mean total sugars intake and 8-day mean 24uSF (r = 0.56, p < 0.001). Similarly, added sugars were moderately correlated with 24uSF (r = 0.56, p < 0.001), while no correlation was found between naturally-occurring sugars and 24uSF (r = 0.070, p < 0.001). In a linear multiple regression, total and added sugars each explained 30% of variability in 24uSF (Adjusted R2, p value; total sugars: 0.297, 0.001; added sugars: 0.301, p < 0.001). Physical activity had no effect on the association between dietary and urinary sugars in neither the correlation nor the linear regression analysis. 24uSF can be used as a biomarker for total and added sugars consumption in US adults, although its predictability was weaker compared to findings involving UK adults. No evidence was found showing that physical activity levels affect the association between 24uSF and total sugars intake in US adults. More detailed investigation through future feeding studies including subjects with wide range of sugars intake and of different ethnic/racial backgrounds are needed to better understand the characteristics of the biomarker and its uses.

Objective: The Special Supplemental Nutrition Program for Women, Infants and Children (WIC) is a federally-funded program that provides supplemental food packages, nutrition education, and healthcare referrals to low-income women, infants, and children under 5, who are at the highest nutritional risk. This study explores if household WIC participation is associated with healthier dietary behaviors among age-ineligible children (5-18-years-old) in WIC households. Consumption frequency of fruits, vegetables, 100% juice, sugar-sweetened beverages (SSBs), and energy-dense snacks (sweet and salty snacks) among children from WIC and income-qualifying non-WIC households were compared.

Methods: Data were obtained from two cross-sectional panels (2009-10 and 2014) of the New Jersey Child Health Study conducted in four low-income New Jersey cities. Questions from previously validated surveys assessed consumption frequency of fruits, vegetables, SSBs, and sweet and salty snacks. Analyses were confined to 570 children between 5-18 yrs; of which 365 (5-11 yrs: 237, 12-18 yrs: 128) resided in WIC participating households and 205 (5-11 yrs: 138, 12-18 yrs: 67) in income-qualifying non-WIC households. Over half of the sample was African American and 43% were Hispanic. Multivariable analyses were conducted to compute incidence rate ratios (IRRs) using negative binomial regression to compare the differences in eating behaviors of children in WIC vs. Non-WIC households

Results: Household WIC participation was associated with a slightly higher frequency of vegetable consumption among 12-18-year-old children (IRR= 1.25, p=.05); differences were significant among older males (12-18-years-old) (p=.006), and not in females.

Frequency of 100% juice consumption was significantly higher among younger females (5-11-years-old) in WIC households who consumed juice about 44% more frequently (p=.02) compared to similar age girls in non-WIC households. Hispanic children in WIC households reported a lower frequency of SSBs consumption (p=.01); this association was only true among males (p=.02).

Conclusions: Household WIC participation is associated with healthier dietary behaviors among age-ineligible children living in the households, suggesting a positive spillover effect of the program. Proposed changes to WIC packages are likely to have dietary implications not only for WIC participants but also for non-participating children residing in WIC households,

Background: Higher intake of carbohydrates in the evening and later eating times has been associated with higher total energy intake (TEI)1-3 and higher risk of being overweight or obese.1,4 Though existing evidence indicates a link between added sugars intake and increased body mass index (BMI), the effect of daily patterns of added sugars intake on TEI and BMI is unknown. Research on added sugars has relied on self-report dietary assessments with limited days of dietary data, resulting in unreliable estimates. The purpose of this thesis was to describe patterns of added sugars consumption, and to investigate the relationship between dietary sugars, eating patterns, TEI, and BMI using 15-days of dietary data from a feeding study. Methods: 40 participants age 18 to 70 years completed a 15-d highly controlled feeding study which imitated their normal diet, while recording meal times. Meals and snacks were coded based on participant identified, time-of-day, and meal content specific criteria. All consumed foods and beverages were carefully weighed and entered into the Nutrition Data System for Research (NDSR) for analysis. Pearson correlation, independent t-test, one-way repeated measures analysis of variance (ANOVA) with post hoc tests, and multiple linear regressions were used to investigate the association between patterns of added sugars and energy intake, as well as eating frequency (EF), with TEI and BMI. Results: 15-d median added sugars intake was 9.7% of total calories. The highest contribution to added sugars intake (% of g/d) came from snacks (44%) in women and from afternoon (39%) consumption in men. The highest contribution to TEI came from dinner (30%) and afternoon (34%) consumption in women, and from lunch (31%) or dinner (30%) and afternoon (35%) consumption in men. Total eating occasion (EO) frequency had a negative association with TEI (r = -0.31) and no association with % energy from added sugars. In multivariate regression models, besides sex, % energy from beverages only (Adjusted R2 = 0.41) and % added sugars from dinner (Adjusted R2 = 0.39) were significant predictors of TEI, while none of the variables were associated with BMI. Conclusion: Changing one’s pattern of eating, (EF and % energy from beverages only and % added sugars from dinner), may reduce TEI, potentially reducing BMI.

Background: Twenty-four hour urinary sucrose and fructose (24uSF) has been developed as a dietary biomarker for total sugars intake. Collection of 24-h urine is associated with high costs and heavy participant burden, while collection of spot urine samples can be easily implemented in research protocols. The aim of this thesis is to investigate the utility of uSF biomarker measured in spot urine. Methods: 15 participants age 22 to 49 years completed a 15-day feeding study in which they consumed their usual diet under controlled conditions, and recorded the time each meal was consumed. Two nonconsecutive 24-hour urines, where each urine void was collected in a separate container, were collected. Four timed voids (morning, afternoon, evening, and next day) were identified based on time of void and meal time. Urine samples were measured for sucrose, fructose and creatinine. Variability of uSF excretion was assessed by coefficient of variation (%CV) and variance ratios. Pearson correlation coefficient and multiple linear regression were used to investigate the association between uSF in each timed void and corresponding 24uSF excretion. Results: The two-day mean uSF was 50.6 mg (SD=29.5) for the 24-h urine, and ranged from 4.5 to 7.5 mg/void for the timed voids. The afternoon void uSF had the lowest within-subject variability (49.1%), and lowest within- to between-subject variance ratio (0.2). The morning and afternoon void uSF had the strongest correlation with 24-h uSF for both mg/void (r=0.80 and r=0.72) and mg/creatinine (r=0.72 and r=0.67), respectively. Finally, the afternoon void uSF along with other covariates had the strongest predictive ability of 24-h uSF excretion (mg/void) (Adjusted R2= 0.69; p=0.002), whereas the morning void had the strongest predictive ability of 24-h uSF excretion (mg/g creatinine) (adjusted R2= 0.58; p=0.008). Conclusions: The afternoon void uSF had the most favorable reproducibility estimates, strong correlation with 24uSF excretion, and explained greatest proportion of the variability in 24uSF. USF in mg/void may be better to use than uSF in mg/g creatinine as a biomarker in spot urine. These findings need to be confirmed in a larger study, and in a study population with a wide range of sugars intake.

Fruit and vegetable consumption among school children falls short of current recommendations. The development of Public-Private Partnerships (PPP), which combine the resources of government entities with the resources of private entities, such as businesses or not-for-profit agencies, has been suggested as an effective approach to address a number of public health concerns, including inadequate fruit and vegetable consumption. The United States Department of Agriculture's (USDA) Fresh Fruit and Vegetable Program (FFVP) provides fruits and vegetables as snacks at least twice per week in low-income elementary schools. In addition to increasing fruit and vegetable consumption behaviors at school, children participating in the FFVP have been found to make more requests for fruits and vegetables in grocery stores and at home, suggesting the impact of the program extends beyond school settings. The purpose of this multicase study was to describe key stakeholders' perceptions about creating PPPs between schools and nearby retailers to cross-promote fruits and vegetables in low-income communities, using the FFVP. Semi-structured interviews were conducted with participants from three cases groups: grocery store/produce managers (n=10), district FFVP personnel (n=5) and school FFVP personnel (n=12). Data were analyzed using a directed content analysis approach using constructs from the Health Belief Model, including benefits, barriers, strategies, and motivation. While findings varied by case group, key benefits of creating a PPP included the potential to increase store sales, to enhance public relations with the community, and to extend the impact of the FFVP to settings outside of schools. Barriers included offering expensive produce through the FFVP, time/labor-associated costs, and needing approval from authorities and supervisors. Strategies for developing a PPP included using seasonal produce and having clear instructions for teachers and staff. Stakeholders reported being motivated to create a PPP by the potential to improve health outcomes in children and by wanting to help the community. Both objective and subjective measures were suggested to measure the success of such a partnership. Finally, the educational component of the USDA's Supplemental Nutrition Assistance Program (SNAP-Ed) has the potential to serve as a catalyst for organizing a PPP between FFVP-participating schools and nearby grocery stores.