UMD Theses and Dissertations
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Item COMPARISON OF ACRYLAMIDE EXPOSURE BIOMARKERS IN CHILDREN AND ADOLESCENTS USING NATIONAL HEALTH AND NUTRITION EXAMINATION SURVEY (NHANES) 2003-04 AND 2015-16(2024) Vallejo, Jessica Vasquez; Turner, Paul C; Kadry, Abdel; Maryland Institute for Applied Environmental Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Acrylamide (AA) is an important industrial chemical of occupational concern due to its neurotoxicity and probable carcinogenicity; it is also a tobacco burning product and thus contributes to health concerns in smokers. More recently it was discovered to be thermally generated in the cooking of starch-rich foods, creating a potentially wider public health concern. Children and adolescents are a particularly vulnerable group because they consume more acrylamide-rich foods compared to adults. In addition, they are still going through important developmental stages. This study examines AA and its metabolite glycidamide (GA) using hemoglobin adduct biomarkers (HbAA and HbGA respectively) from the U.S. children (6-11) and adolescents’ (12-19) National Health and Nutrition Examination Survey’s 2003-04 (n=2814) and the 2015-16 (n=697). The study investigated changes in exposure over time and examined the contribution of potential modifiers including smoking status, race/ethnicity, poverty-to-income ratio, sex, and age. All HbAA and HbGA are reported as pmoL adduct per gram Hb (pmol/G Hb).Overall, HbAA biomarkers significantly (p<0.0001) declined from 2003-04, GMs (95% CI) (57.9 [55.7, 60.1] pmol/G Hb) versus (42.8 [41.4, 44.2] pmol/G Hb) in 2015-16 for all ages, with similar reductions observed in the individual children and the adolescent groups. Smokers had a higher burden of HbAA biomarkers than non-smokers, and with a significant reduction in numbers of smokers from 2003-04 to 2015-16, this likely contributes to the reduction in overall exposure. When non-smokers only were examined, a significant (p<0.0001) decrease in HbAA was still observed, from 2003-04 GMs (95% CI) (53.4 [52.0, 54.9] pmol/G Hb) versus (41.2 [40.2, 42.2] pmol/G Hb) in 2015-16, suggesting an additional contribution of changes in AA levels in food or frequency of high-risk food consumption. Similar statistically significant reductions were seen for both children and adolescent groups separately. HbGA is a marker of AA biotransformation to GA, which is a more mutagenic metabolite of AA. The ratio is of HbAA:HbGA is a phenotypic marker of mutagenic risk. In non-smokers, there was a significant (p=0.001) difference in the HbAA:HbGA ratio in children GMs (95% CI) (0.8 [0.8, 0.8] pmol/G Hb) at 2003-04 and (0.9 [0.9, 1.0] pmol/G Hb) at 2015-16 versus adolescents (1.0 [1.0, 1.1] pmol/G Hb) at 2003-04 and (1.1 [1.0, 1.2] pmol/G Hb) at 2015-16, respectively, suggesting children may be at greater risk to the mutational effects of AA exposure compared to adolescents. In multivariate regression analysis of non-smokers only, age and race significantly contributed to the HbAA biomarker levels, with higher HbAA in younger age groups and in non-Hispanic black participants, highlighting a disparity in exposure pattern. Overall, AA exposure seems to have reduced from 2003-04 to 2015-16; the reduction is driven by both changes in smoking but also diet. The young and non-Hispanic black participants remain at highest risk of exposure and potential health effects from exposure to AA.Item EXAMINATION OF THE ASSOCIATIONS BETWEEN SELECTED PERFLUOROALKYL SUBSTANCES AND THEIR ISOMERS WITH BODY WEIGHT IN ADOLESCENTS USING NHANES 2013-2018(2023) Snyder, Jessica A; Payne-Sturges, Devon; Maryland Institute for Applied Environmental Health; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)0ABSTRACT Title of thesis: EXAMINATION OF THE ASSOCIATIONS BETWEEN SELECTED PERFLUOROALKYL SUBSTANCES AND THEIR ISOMERS WITH BODY WEIGHT IN ADOLESCENTS USING NHANES 2013-2018 Jessica Snyder, Master of Science, 2023 Thesis Directed by: Professor Devon Payne-Sturges Maryland Institute for Applied Environmental Health Perfluoroalkyl substances (PFAS), a class of environmentally persistent chemicals, are suspected of having obesogenic properties, with studies thus far being inconclusive. Few past studies of PFAS toxicity have distinguished between isomer types of each PFAS group during analysis, however. In this thesis, data for non-smoking 14-19 year-olds from three cycles of the National Health and Nutrition Examination Survey was analyzed to identify potential associations in adolescents between bodyweight and two major families of PFAS: perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) and to additionally determine if differentiating between linear and branched isomeric groups of two major PFAS families could better elucidate any associations found. In unadjusted models, weighted linear regression of body mass index (BMI) and serum concentrations of branched, linear, and total PFAS isomer groups, all returned positive associations ranging from β (95% confidence interval) of 4.06 (3.44, 4.68) for total PFOS to 12.33 (10.39,14.28) for linear PFOA. When models were adjusted for sex, age, race/ethnic origin and income level, however, only a negative association between BMI and branched PFOS (bPFOS) was found, with β= -1.24 (-2.10, -0.39). Unadjusted weighted logistic regression models of both overweight and obese status resulted in positive associations between obesity and both branched PFOS and total PFOS with odds ratios (95% confidence intervals) of 0.45 (0.27, 0.74) and 0.86 (0.75, 0.99) respectively. After adjusting for potential confounders, the only statistically significant relationship was between branched bPFOS and obesity, with a 56% decrease in the odds of obesity for every unit increase in serum concentration of bPFOS [β =-1.06, adjusted odds ratio= 0.44 (0.26,0.76)]. There was no significant difference between the sexes in any results. The apparent protective effect that bPFOS has against obesity and elevated BMI, notable as a health outcome association in itself, also illustrates that isomeric differentiation is important in studying PFAS, as nPFOS had no statistically significant 1 association by itself while ΣPFOS, used by many studies, did. Thus, the lack of differentiation could mask which PFAS type contributes to any associations discovered.Item Flavonoids, Cardiovascular Disease, and Diabetes(2019) Gahche, Jaime; Sahyoun, Nadine R; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Background: Flavonoids have been shown to have anti-inflammatory, antioxidant, and vasodilatory properties; mechanisms that may lead to cardio-protective benefits. Results from observational studies assessing the associations between flavonoid intake and cardiovascular disease (CVD) and type 2 diabetes mellitus have been largely equivocal. Earlier studies were limited due to lack of complete flavonoid composition databases. With the development of more complete databases, total flavonoid intake can be more accurately estimated, but the associations between them and CVD and diabetes have not been assessed in a nationally representative sample of the U.S. population. Aims: The objective of this study was to assess the relationship between dietary intake of flavonoids and risk of: 1) CVD outcomes, and 2) diabetes. Methods: Baseline data from the Third National Health and Nutrition Examination Survey (NHANES III) were collected from participants in 1988-1994 and linked with administrative records to identify CVD and diabetes outcomes. The National Death Index was used for mortality and CMS Medicare Claims and Medicare enrollment data to identify initial events. Flavonoid intake was assessed with up to four 24-hour dietary recalls and the USDA’s flavonoid databases were used to assign flavonoid values to reported food and beverage consumption. Usual intakes of flavonoids and flavonoid sub-classes were estimated using the NCI method. Hazard ratios and 95% confidence intervals were estimated using Cox proportional hazards regression modeling. Results: In this nationally representative sample of adults, from a 1988-1994 constructed cohort and followed passively for over 20 years, significant inverse associations between total flavonoids or sub-classes and CVD outcomes or diabetes were not evident. However, there was a marginal association between flavanones and CVD mortality, for males only (HR =0.93, 95 % CI 0.87, 1.00, p-value<0.04). Conclusions: In this population-based sample of individuals, associations between intakes of flavonoid and CVD mortality (with the exception of flavanone intake for men only), CVD morbidity or diabetes were not evident after 20 years of follow-up. This may be due to their low levels of usual intake, to errors in measurement of flavonoid intake, or misclassification over time of flavonoid intakes, or relatively small sample sizes.Item ASSOCIATIONS OF HEALTH MARKERS, PERCEPTIONS, AND LIFESTYLE BEHAVIORS WITH DIET QUALITY INDICES AND TYPE 2 DIABETES STATUS IN U.S. ADULTS(2018) Al-Ibrahim, Afnan Abdul Hamid; Jackson, Robert T; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)There is growing evidence that adherence to healthful dietary patterns reduces the risk of type 2 diabetes (T2DM). The Healthy Eating Index 2010 (HEI-2010) and the Alternate Healthy Eating Index 2010 (AHEI-2010) are recognized as assessment tools for measuring dietary quality. This research had three main objectives: 1) Determine whether the AHEI-2010 provides a more accurate assessment of dietary quality than the HEI-2010 in relation to diabetes status; 2) Examine the relationship between diabetes status and discrepancies between perceived diet quality (PDQ) and measured diet quality (MDQ) (using total HEI-2010 and AHEI-2010 scores, respectively); 3) Examine the relationships between selected lifestyle behaviors independently, and in combination with other lifestyle behaviors, and dietary quality (using total HEI-2010 and AHEI-2010 scores) by diabetes status. Data from the National Health and Nutrition Examination Survey (NHANES) 2007-2010 were used to analyze participants age 20 years and older (n = 4097). Overall, the total HEI-2010 and AHEI-2010 scores for the sample indicate that U.S. adults need dietary improvement (mean total HEI-2010 score = 47.3 ± 0.4; mean total AHEI-2010 score = 38.2 ± 0.4). Diabetics had higher total HEI-2010 and AHEI-2010 scores compared to prediabetics and non diabetics, but did not have better health markers. Results indicate no predictive value of total HEI-2010 and AHEI-2010 scores (OR = 1.00, p > 0.05) in relation to diabetes status. In addition, the associations between diabetes status and discrepancy scores (for both HEI-2010 and AHEI-2010) were not significant after adjusting for perceived health status (p > 0.05). However, there were significant associations between individual lifestyle behaviors and total HEI-2010 and AHEI-2010 scores by diabetes status (p < 0.05). In addition, the combined Lifestyle Behaviors score was a significant predictor of total HEI-2010 and AHEI-2010 scores (p < 0.05) by diabetes status. In conclusion, these findings suggest that dietary quality, measured with HEI-2010 or AHEI-2010 is associated with health markers, perceptions, and lifestyle behaviors, all of which can influence the development of T2DM. Findings of this research have implications for developing more successful strategies to improve compliance with dietary guidelines and evidence-based recommendations for disease management and prevention.Item INVESTIGATING THE ASSOCIATION OF PHTHALATE EXPOSURES AND ADVERSE REPRODUCTIVE HEALTH OUTCOMES IN A REPRESENTATIVE SAMPLE OF U.S. WOMEN(2017) Bibb, Katrina Alexandra; Alcala, Lesliam Q; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Phthalates are endocrine disrupting chemicals present in a large variety of consumer goods. There is supporting evidence from animal studies that exposure to phthalates affect the female reproductive system by disrupting the epigenome and folliculogenesis/oogenesis. Although women of reproductive age experience higher phthalate exposures versus males due to frequent use of cosmetics and personal care products (PCP), studies investigating reproductive health effects of these chemicals are scarce. In this study, a nationally representative sample was used to investigate the association between exposure to phthalates (primarily in PCPs and cosmetics) and subfertility in women aged 18-44. We observed significantly higher phthalate levels among minority women and positive associations between DBP exposure and subfertility in regressions when adjusted for important covariates This is the first study to use such a sample of women to study the effects of phthalates on subfertility. More epidemiological studies are needed to investigate phthalate levels among minorities.Item ASSOCIATION OF SERUM VITAMIN D AND KEY CO-NUTRIENTS IN RELATION TO HYPERTENSION: A CROSS-SECTIONAL STUDY BASED ON NHANES DATA(2016) Barainca, Pamela; Carter-Pokras, Olivia; Epidemiology and Biostatistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Observational studies demonstrate strong associations between deficient serum vitamin D (25(OH)D) levels and cardiovascular disease. To further examine the association between vitamin D and hypertension (HTN), data from the 2003-2006 National Health and Nutrition Examination Survey were analyzed to assess whether the association between vitamin D and HTN varies by sufficiency of key co-nutrients necessary for metabolic vitamin D reactions to occur. Logistic regression results demonstrate independent effect modification by calcium, magnesium, and vitamin A on the association between vitamin D and HTN. Among non-pregnant adults with adequate renal function, those with low levels of calcium, magnesium, and vitamin D levels had 1.75 times the odds of HTN compared to those with sufficient vitamin D levels (p = <0.0001). Additionally, participants with low levels of calcium, magnesium, vitamin A, and vitamin D had 5.43 times the odds of HTN compared to those with vitamin D sufficiency (p = 0.0103).Item Associations between Urinary Phthalates and Metabolic Syndrome in NHANES 2005-2010(2015) Haque, Mefruz Salwa; Dallal, Cher M; Epidemiology and Biostatistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Phthalates, commonly used to make plastics more durable, are a group of endocrine disrupting chemicals (EDC), with potential for adverse metabolic consequences. Associations between exposure to 13 phthalate metabolites and the prevalence of metabolic syndrome (MetS) were examined among 5,409 U.S adults ≥ 18 years of age, who participated in the National Health and Nutrition Examination Survey from 2005-2010. MetS was assessed using clinical and questionnaire data. Odds Ratio (OR) and 95% Confidence Intervals (CI) adjusting for age, creatinine and key confounders, were estimated with multivariable logistic regression. Positive associations were observed between individual phthalate metabolites and MetS: (MCOP OR=1.31, 95% CI=1.40, 1.64, p-trend<.01; MCPP OR=1.39, 95% CI=1.09, 1.77, p-trend=0.01). In gender stratified analyses, findings with MCOPP and MCPP were restricted to women only. Phthalate metabolites may increase the prevalence of MetS; however, further studies are needed to better understand the role of EDCs in the development of MetS.Item Folate intake and biomarkers and risk of chronic disease(2014) Hu, Jing; Sahyoun, Nadine R; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Background: Folate status of the U.S. population significantly improved after folic acid fortification of enriched cereal-grain products in 1998. Recent evidence suggests that the increased folate levels may have impacts on the risk of chronic disease. The kidneys are known to be highly involved in folate metabolism. Reduced renal function may affect folate metabolism and play a role in the associations between folate and chronic disease. Objectives: The purpose of this study was to review key events regulating folate homeostasis along folate metabolic pathway. In addition, we examined the associations between folate intake and biomarker levels and the incidence of cancer, stroke and cardiovascular disease (CVD) and between folate biomarker levels and renal function among older adults in post-fortification years. Design: The Key Events Dose-Response Framework was used to review key steps of folate metabolism. Data of adult participants of the National Health and Nutrition Examination Survey 1999-2002 were used as the baseline data. Incidence of cancer, stroke and CVD were obtained from the linked Medicare and mortality files. The associations between folate intake and biomarker levels and incidence of cancer, stroke and CVD, and the associations between estimated glomerular filtration rate (eGFR) and folate biomarkers, serum unmetabolized folic acid (UMFA) and plasma homocysteine levels were assessed using Cox proportional hazards regression models and multivariable regression models, respectively. Results: The saturation of dihydrofolate reductase in the liver is the determining point regulating the release of UMFA in circulation. Lower red blood cell (RBC) folate levels and intake of dietary folate equivalents were associated with a higher cancer incidence. Lower RBC folate and serum folate levels were associated with a higher stroke incidence. No significant associations between folate and CVD were observed. In addition, reduced renal function was associated with higher RBC folate and plasma homocysteine levels among men and women, and higher prevalence of UMFA in blood among women. Conclusion: High intake of folate may disturb folate metabolism by overwhelming folate regulation mechanisms. Folate may play a protective role against cancer and stroke even at high levels in post-fortification years. Reduced renal function may be implicated in the increased blood folate concentrations.Item Associations among food insecurity, dietary sodium and potassium intake levels, and hypertension: a cross-sectional study based on NHANES 2007-2010 data(2014) Nothwehr, Ann; Carter-Pokras, Olivia; Epidemiology and Biostatistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Background: Food insecure persons may have diet patterns that include excessive sodium and inadequate potassium. These patterns contribute to greater risks of hypertension. Objective: Evaluate levels of association among food insecurity, dietary sodium and potassium intake levels and hypertension among NHANES 2007-2010 adult participants. Methods: Compared mean usual sodium and potassium intakes as well as mean usual sodium-potassium ratios for food secure and food insecure subpopulations. Developed regression models to predict intake levels and hypertension risk. Results: Mean usual sodium intake is not significantly different for food secure and food insecure participants. Mean usual potassium intake is significantly lower and mean usual sodium-potassium ratio is significantly higher for the food insecure subgroup. Controlling for age and household size, food insecure persons are 43% more likely to be hypertensive than food secure persons. Conclusion: Public health measures to decrease cardiovascular disease risk should include interventions designed for this vulnerable subpopulation.Item Appropriate Waist Circumference Cutoff Values for the Diagnosis of Metabolic Syndrome in Mexican American Adults(2009) Sarafrazi, Neda; Jackson, Robert T; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Metabolic syndrome increases the risk of cardiovascular disease and diabetes. The International Diabetes Federation (IDF) recently proposed new criteria for the diagnosis of metabolic syndrome, which requires the presence of central obesity as measured by ethnic specific waist circumference (WC) cutoff values. Currently, no specific WC thresholds for diagnosis of central obesity in Hispanics are available. The objectives were to determine the appropriate gender specific WC thresholds for diagnosis of central obesity in Mexican American adults and to estimate the prevalence of metabolic syndrome using IDF definition with and without the modified WC in this population. Data from 3265 Mexican American adults aged 20-80 years who participated in the National Health and Nutrition Examination Survey 1999-2006 were used. The prevalence of metabolic syndrome was compared using IDF criteria with and without the modified waist circumference. Receiver operating characteristic curve analysis suggested that yielding at least 80% sensitivity, the WC value of 90 cm in both genders was more appropriate in predicting the presence of two or more metabolic syndrome risk factors in this population. Based on this cutoff, there was 34% reduction in the prevalence of central obesity in women (82.5% to 54.2%). The age adjusted prevalence of metabolic syndrome decreased from 58.4 to 48.2%. The metabolic syndrome was more common among Mexican American men than women (55.8% in men versus 37.8% in women, P =0.0003). Our findings provided a practical guidance in the assessment and screening of central obesity and metabolic syndrome in Mexican Americans.