THESIS. Alison Lynn Webster, BS. The Ohio State University. Master s Examination Committee: Carolyn Gunther, PhD (Advisor) Julie Kennel, PhD, RD

Transcription

1 Knowledge, Attitudes, and Practices Regarding Dietary Sodium Intake, and Associations with Sodium Consumption and Blood Pressure in College Students THESIS Presented in Partial Fulfillment of the Requirements for the Degree Master of Science in the Graduate School of The Ohio State University By Alison Lynn Webster, BS Graduate Program in Human Nutrition The Ohio State University 2017 Master s Examination Committee: Carolyn Gunther, PhD (Advisor) Julie Kennel, PhD, RD Tonya Orchard, PhD, RD

2 Copyright by Alison Lynn Webster 2017

3 Abstract Background: A majority of college students consume excess sodium. Excessive sodium intake is associated with high blood pressure, a risk factor for cardiovascular disease and stroke. There is a need for behavioral interventions to reduce sodium intake in college students. The primary aim of the present study was to assess the knowledge, attitudes, and practices regarding dietary sodium in convenience samples of college students. A secondary aim was to characterize sodium intake and resting blood pressure in a small convenience sample of students, and subsequently explore associations with sodium knowledge, attitudes, and practices. Methods: Convenience samples of students from a Midwestern university (n=169) and a Pacific Island university (n=152) completed a previously-validated sodium questionnaire. The questionnaire assessed knowledge (27 items with 5 response options; 1 point maximum assigned for correct responses) with higher score representing higher knowledge, attitudes (4 items on 5-point Likert scale) with higher score representing more positive attitudes, and practices (7 items on 5-point Likert scale) with higher scores representing more positive practices. An additional sample of students from the ii

4 Midwestern university (n=35) completed the sodium questionnaire, one-day food records, and resting blood pressure measurements. Results: College students had low knowledge, poor attitudes, and poor practices regarding dietary sodium. In the smaller sample (n=35), mean sodium intake was 3,946 mg per day, and mean systolic and diastolic blood pressures were 116 and 70 mmhg, respectively. There were no significant correlations of sodium knowledge, attitudes, or practices with estimated sodium consumption or blood pressure. Additionally, there were no significant correlations between estimated sodium intake and blood pressure. Conclusions: Students demonstrated low knowledge, poor attitudes, and poor practices regarding dietary sodium, a high dietary sodium intake (more than 1,500 mg per day above the daily recommendation of 2,300 mg per day), and normal blood pressure measurements. In addition, there were no associations of behavioral determinants of sodium intake with dietary sodium intake or blood pressure. Results from this study demonstrate the need for sodium reduction interventions in college students. Future studies should assess additional personal factors and environmental determinants of sodium intake. Future research would also benefit from assessing the barriers to reducing sodium consumption in college student populations. iii

5 Dedication Your Love Will Light My Way Psalm 91:11 This thesis is dedicated in memory of my beloved sister and guardian angel, Pamela Lynn Webster. May your spirit and love continue to shine through in all that we do and guide us to where we are meant to be. iv

6 Acknowledgements First and foremost, a sincere thank you to my advisor, Dr. Carolyn Gunther, for her continuous support, encouragement, and push over the past four years. I appreciate that you always remind me to think critically and to never underestimate my own abilities. I also thank my research committee, Dr. Julie Kennel and Dr. Tonya Orchard, for their guidance, feedback, and inspiration throughout this entire project. I would like to extend further gratitude to Dr. Jinan Banna and Dr. Eunjung Lim at the University of Hawaii at Manoa for their support and collaboration on this research. An enormous thank you to my research lab and fellow graduate students for showing me unending love, guidance, and friendship throughout my entire graduate school career. This study would not have been possible without the team of undergraduate students who dedicated their time to this research. Additional thanks to Dr. Joshua Bomser for allowing our team to recruit participants from his undergraduate nutrition class. Lastly, I would like to thank my family, friends, and boyfriend for continuously cheering me on and lifting up my spirits throughout this entire journey. v

7 Vita June Aurora High School May B.S. Biochemistry, The Ohio State University 2015 to present Graduate Teaching Associate, The Ohio State University Field of Study Major Field: Human Nutrition vi

8 Table of Contents Abstract... ii Dedication... iv Acknowledgements... v Vita... vi Table of Contents... vii List of Tables... ix Chapter 1: Introduction... 1 Chapter 2: Literature Review... 4 Chapter 3: Assessing Knowledge, Attitudes, and Practices Regarding Dietary Sodium Intake in a Multi-State Cohort of College Students Chapter 4: Exploring Associations between Sodium Knowledge, Attitudes, and Practices, Sodium Consumption, and Blood Pressure in College Students Chapter 5: Epilogue References vii

9 Appendix A: Fall 2015 Sodium Questionnaire Appendix B: Fall 2016 Sodium Questionnaire Appendix C: Anthropometric and Biometric Data Collection Sheet viii

10 List of Tables Table 1. Demographics of OSU and UH Participants 32 Table 2. Mean Total Construct Scores by University 37 Table 3. Percentages of High and Low Construct Scores by University.. 38 Table 4. Individual Knowledge Items Compared Across University.. 39 Table 5. Individual Attitude Items Compared Across University. 41 Table 6. Individual Practice Items Compared Across University. 42 Table 7. Additional Items Compared Across University Table 8. Individual Knowledge Items Compared Across Sex at OSU 47 Table 9. Individual Attitude Items Compared Across Sex at OSU.. 49 Table 10. Individual Practice Items Compared Across Sex at OSU 50 Table 11. Additional Items Compared Across Sex at OSU.. 51 Table 12. Individual Knowledge Items Compared Across Race at OSU. 52 Table 13. Individual Attitude Items Compared Across Race at OSU 54 Table 14. Individual Practice Items Compared Across Race at OSU 55 Table 15. Additional Items Compared Across Race at OSU.. 56 Table 16. Individual Knowledge Items Compared Across Sex at UH.. 57 ix

11 Table 17. Individual Attitude Items Compared Across Sex at UH. 59 Table 18. Individual Practice Items Compared Across Sex at UH. 60 Table 19. Additional Items Compared Across Sex at UH 61 Table 20. Individual Knowledge Items Compared Across Race at UH.. 62 Table 21. Individual Attitude Items Compared Across Race at UH Table 22. Individual Practice Items Compared Across Race at UH Table 23. Additional Items Compared Across Race at UH Table 24. Demographics of OSU Human Nutrition Course Participants. 83 Table 25. Mean Estimated Intakes, Biometrics, and Anthropometrics across Sex in OSU Human Nutrition Course Participants. 86 Table 26. Mean Total Construct Scores for OSU Human Nutrition Course Participants Table 27. Individual Knowledge Item Scores for OSU Human Nutrition Course Participants 88 Table 28. Individual Attitude Item Scores for OSU Human Nutrition Course Participants 90 Table 29. Individual Practice Item Scores for OSU Human Nutrition Course Participants Table 30. Additional Item Scores for OSU Human Nutrition Course Participants.. 92 Table 31. Pearson Correlations among Main Outcome Variables x

12 Chapter 1: Introduction The Dietary Guidelines for Americans recommends that persons 14 years old consume less than 2,300 mg of dietary sodium per day [1]. According to the National Health and Nutrition Examination Survey (NHANES) data from , 89% of adults (aged 19 years old) exceed the 2,300 mg of sodium per day recommendation, with a mean daily sodium intake of 3,552 mg of sodium [2]. Among the adult population surveyed, the subgroup of persons aged years old report the highest estimated mean daily sodium intake of 3,744 mg of sodium, with 92.1% of the group consuming beyond the 2,300 mg of sodium per day recommendation [3]. Overconsumption of sodium is strongly associated with hypertension, a known risk factor for cardiovascular disease and stroke [4]. Cardiovascular disease is the leading cause of death in both men and women, and uncontrolled hypertension accounts for nearly $964 million in direct medical costs each year [5]. Substantial evidence suggests that a nationwide reduction in sodium intake would provide major public health benefits linked to hypertension, including lower incidences of cardiovascular disease and mortality [6]. Therefore, the nation s excessive intake of dietary sodium has been marked a major public health concern and efforts have been directed towards 1

13 developing and implementing strategies aimed at reducing dietary sodium intake [7]. Nutrition knowledge and beliefs are positively related to diet quality. Individuals with poor nutrition knowledge and beliefs are more likely to consume a lower quality diet, which includes a higher sodium intake [8-9]. In order to develop effective strategies to reduce sodium intake, there is a need to evaluate the knowledge, attitudes, and practices regarding dietary sodium with validated survey tools, particularly in populations at risk for excessive sodium consumption. College students are one particular population at risk for overconsumption of dietary sodium as they transition into a period of newfound independence [10-12]. Studies suggest that college students, typically ages years old, follow poor dietary practices, including the overconsumption of dietary sodium [13]. Data from the Young Adult Health Risk Screening Initiative indicate that male college students and female college students have an estimated mean daily sodium intake of 4,335 mg of sodium and 3,004 mg of sodium, respectively [14]. Dietary habits established in young adulthood are known to transcend into later adulthood [15-16], and well-informed efforts to reduce sodium intake in college students are needed. To our knowledge, no effort has been made to assess the cognitive, affective and behavioral determinants of sodium intake using validated tools in the nutritionally atrisk population of college students. Additionally, associations among the determinants of sodium intake with estimated sodium consumption and resting blood pressure have not been determined in college student populations. The purpose of this research 2

14 project was to first use a validated questionnaire to assess the knowledge, attitudes, and practices regarding dietary sodium intake in college students; Secondly, to characterize sodium intake and blood pressure in college students and subsequently explore if associations exist between sodium knowledge, attitudes, and practices, estimated sodium consumption, and resting blood pressure. We hypothesized that college students would have low knowledge, poor attitudes, and poor practices regarding dietary sodium. The specific aims of this study were to: 1) Determine the knowledge, attitudes, and practices regarding dietary sodium in a college student population utilizing a validated sodium survey tool. 2) Characterize sodium intake and resting blood pressure in a college student population, and subsequently explore associations with sodium knowledge, attitudes, and practices. 3

15 Chapter 2: Literature Review Relationships among Hypertension, Cardiovascular Disease, and Stroke Blood pressure values are considered normal when measurements are 120/80 mmhg. High blood pressure, also known as hypertension, is defined as a systolic blood pressure measurement of 140 mmhg and/or a diastolic blood pressure measurement of 90 mmhg [17]. The Framingham Heart Study, a major break through study in the understanding of cardiovascular disease risk factors using a large cohort of healthy adults (n=4,469), first revealed that hypertensive individuals had a 4-fold increase in probability of developing coronary heart disease compared to normotensives [18-19]. Later, results from the same study revealed that hypertensive individuals had a 5-fold increase in probability of experiencing a stroke compared to normotensives [19-20]. Since then, the results of prospective cohort studies have supported the link between hypertension and the incidence of cardiovascular disease and stroke [21]. Today, hypertension accounts for approximately 47% of ischemic heart disease events and approximately 54% of all strokes across the globe [22]. 4

16 Prevalence of Hypertension among College Students There have been mixed results regarding the prevalence of hypertension among college student populations. A study conducted in college students at Alexandria University (n=600) found that 6% of students had mild high blood pressure ( mmhg systolic blood pressure, mmhg diastolic blood pressure), and 1% of students had moderate high blood pressure ( mmhg systolic blood pressure, mmhg diastolic blood pressure) [23]. Similarly, a coronary heart disease (CHD) risk-screening study measured blood pressure values in male and female students (n=122) attending an east coast university. Systolic blood pressures ranged from mmhg, with an average systolic blood pressure of 122 mmhg. Diastolic blood pressures ranged from mmhg, with an average diastolic blood pressure of 76 mmhg. Over 10% of participants had systolic blood pressure values 140 mmhg and nearly 12% of participants had diastolic blood pressure values 90 mmhg [24]. Conversely, results from the University of New Hampshire s Young Adult Health Risk Screening Initiative revealed troubling data with a much higher prevalence of hypertension among college students. Blood pressure measurements were collected from a sample of male (n=484) and female (n=1,217) students between the ages of years old. Alarmingly, 83% of males and 29% of females had a systolic blood pressure 120 mmhg. Additionally, 43% of males and 33% of females had a diastolic blood pressure 80 mmhg. In total, 47% of students had a systolic blood pressure 120 mmhg, and 39% of students had a diastolic blood pressure 80 mmhg [14]. The prevalence of 5

17 high blood pressure in college students is a public health concern. Multiple studies have have found that young adults with high blood pressure are predisposed to experiencing hypertension as middle-aged adults [25-26]. Strategies and interventions may be needed to reduce and prevent hypertension in college students and reduce the risk for adverse cardiovascular health outcomes later in life. The Relationship between Sodium Intake and Hypertension The relationship between excessive sodium consumption and high blood pressure has become widely known and accepted. The INTERSALT study was a worldwide, cross-sectional epidemiological study assessing the relationship between 24-hour sodium excretion and blood pressure in men and women (n=10,079) between the ages of years old from 32 different countries. Results indicated a significant, positive and independent linear relationship between 24-hour sodium excretion and systolic blood pressure (p-value<0.05) [27]. Findings from the same study using a crosspopulation sample (n=52) indicated that 24-hour sodium excretion was significantly associated with the slope of systolic and diastolic blood pressure with increasing age (pvalue<0.001) [28]. Results of the INTERSALT study confirmed the results of several previously conducted cross-sectional studies that revealed a positive linear association between dietary sodium intake and blood pressure across populations [29-30]. Since the INTERSALT study, numerous observational, epidemiological, and randomized clinical trials have supported the positive relationship between excessive 6

18 sodium intake and high blood pressure [31-34]. Multiple human trials have shown that decreasing dietary sodium intake causes a decrease in blood pressure. For example, the Dietary Approaches to Stop Hypertension (DASH) study was conducted in healthy adults (n=412), and compared the effects of a typical high-sodium, western diet and a lowsodium DASH diet on blood pressure measurements. Results indicated that the DASH diet with a low-sodium level was associated with a significantly lower systolic blood pressure than the typical western diet [35]. The underlying mechanism of excessive sodium intake and high blood pressure remains a topic of study today. It is well understood that sodium retention can cause an expansion of extracellular volume and consequently increase cardiac output [36]. Additionally, studies have confirmed that high sodium concentrations cause a dysfunction in the renin-angiotensin system, which normally regulates blood pressure [37-38]. While many research studies have been conducted, the full underlying mechanism of excessive sodium consumption and high blood pressure is complex and is not yet fully understood. Consequently, some scientists have debated that consuming too low of sodium levels may actually be associated with an increase in cardiovascular disease risk [39]. A major limitation of sodium research is the difficulty in measuring sodium intake long-term, therefore, future studies will be necessary to fully explain and confirm the underlying dynamic between sodium and blood pressure. 7

19 Sodium Intake and Diet Quality in College Students The typical dietary patterns of college students are conducive of excessive sodium consumption. Diets often include high sodium containing items such as fried foods, fast-foods, and prepared foods [40]. A study performed in students (n=290) at a pacific northwestern university measured dietary patterns of students at the beginning of their first-year of college and again during a follow-up at the end of their second-year of college. Over 40% of participants indicated that they had consumed 3 fried foods in the previous week during both their first-year and the second-year follow-up. Additionally, over one half of the participants consumed 3 high-fat fast food meals in the previous week during their first-year in college and also during the second-year follow-up [41]. Similarly, a study conducted in a diverse student sample (n=1,059) found that 45% of participants purchased prepared food away from home at 3 times per week [42]. Studies conducted in college students have consistently confirmed that the majority of students consume beyond the 2,300 mg of sodium per day recommendation [1]. A cross-sectional, exploratory study was performed in first- and second-year students (n=43) at an east coast university. Four-day food records, including three weekdays and one weekend day records, were collected to measure estimated sodium intake. Mean sodium intake for males was 3,953 mg per day, and mean sodium intake for females was 2,855 mg per day [43]. Similarly, the University of New Hampshire s Young Adult Health Risk Screening Initiative study measured estimated sodium intake 8

20 using a three-day food record from males (n=484) and females (n=1,217) enrolled in an introductory level nutrition course. Results showed that only 6% of males and 27% of females consumed 2,300 mg of sodium per day. Males and females had a mean estimated sodium intake of 4,335 mg per day and 3,004 mg per day, respectively [14]. As typical student dietary patterns would indicate, students may not be aware of or interested in reducing their sodium intake. A lifestyle intervention study conducted at a southeastern university measured dietary practices in students (n=37) prior to a 12- week nutrition education intervention. Before the intervention, only 60% of respondents indicated that they Actively try to avoid high salt foods [44]. Given that sodium consumption is high and numbers actively trying to reduce sodium intake are low, interventions may be necessary to motivate college students to reduce their sodium intake. Relationships among Knowledge, Attitudes, Practices, and Overall Diet Quality Studies have indicated that knowledge, attitudes, and practices are determinants of overall diet quality. Evidence indicates that nutrition knowledge and beliefs are positively related to diet quality in adult populations [8]. A cross-sectional study assessed the association between nutrition knowledge and dietary fat consumption among college students (n=231). Nutrition knowledge was measured using a previously validated questionnaire, and dietary fat consumption was measured with a block dietary fat screener. There was a significant association between nutrition knowledge and total 9

21 fat intake, saturated fat intake and cholesterol intake in college students (pvalue<0.001) [45]. Additionally, a cross-sectional study performed in low-, medium-, and high-cost supermarkets analyzed the association between attitudes towards healthy eating behaviors and diet quality among adult participants (n=963). Study results indicated that attitude toward healthy eating was a key predictor in diet quality among supermarket shoppers, and that a more positive attitude toward healthy eating was associated with higher diet quality at all supermarket cost levels (p-value<0.05) [46]. Similarly, a cross-sectional study conducted in college students (n=1201) from a twoyear and four-year college determined the associations between attitudes towards healthy eating, nutrition label use, and diet quality. Results showed that attitude towards preparing healthy meals was a significant predictor of total healthy dietary practices in college students (p-value<0.001). Additional findings suggested that nutrition label use was a partial mediator between attitude towards preparing healthy meals and diet quality (p-value<0.001) [47]. More specifically related to sodium, studies performed around the globe have determined that sodium knowledge and attitudes are predictors of self-reported, sodium-related dietary behaviors. A validated sodium knowledge, attitudes, and practices questionnaire was completed in sample of adults in the Middle-East (n=500). Participants who correctly recognized that salt can worsen overall health and/or that identified processed foods as a main source of sodium were more likely to cut down on their sodium intake. Similarly, participants who correctly identified the relationship 10

22 between salt and sodium were more likely to indicate that the salt content of foods influenced their purchasing decision. In addition, participants who indicated they were concerned about the amount of sodium in their diet were more likely to adopt favorable sodium-related dietary habits [9]. A similar study conducted in Canadian adults (n=3,130) utilized a telephone interview to assess knowledge, attitudes, and self-efficacy related to sodium. Results indicated that participants who believed sodium reduction was important were more likely to also indicate they were actively reducing their sodium intake [48]. The studies that found knowledge and attitudes to be predictors of sodium-related dietary behaviors used self-reported behaviors as surrogates of sodium intake behavior. A gap in the literature remains as to the association between the determinants of sodium intake and actual sodium consumption measured by dietary intake tools or urinary sodium excretion. Knowledge, Attitudes, and Practices Regarding Dietary Sodium in Various Populations While knowledge, attitudes, and practices regarding dietary sodium intake are understudied in college students, questionnaires have been created, validated, and utilized to assess determinants of sodium intake in multiple populations across the globe. Recent literature suggests that multiple populations are at-risk for low knowledge regarding dietary sodium. A Salt Consumer Survey study recruited Australian adults 18 years old (n=1000) to complete phone interview surveys. The survey responses indicated that only 34% of respondents were able to correctly indicate the relationship 11

23 between salt and sodium [49]. In 2012, Claro et al. designed and validated a questionnaire to assess knowledge, attitudes, and practices related to sodium consumption in healthy adults. A convenience sample of adults (n=1992) from Chile, Ecuador, Argentina, Costa Rica and Canada completed the questionnaire at local shopping malls in each country. Results indicated that only 26% of participants reported knowing of a recommended maximum value of daily sodium intake [50]. Studies also suggest that multiple populations are at-risk for poor attitudes regarding dietary sodium. Multiple studies in healthy adult populations have found that less than half of participants believe they consume the right amount of sodium per day [48]. One study found that 42% of healthy Australians (n=1000) are not cutting down on their sodium intake because they believe they do not have too much sodium in their diet [49]. A second study found that only 30% of healthy adults from sentential countries in Latin America (n=1992) believe that reducing daily sodium intake is important, and only 47% of participants report that they know the sodium content of commonly eaten food items [50]. A further study found that only 46% of healthy adult participants from Melbourne, Australia (n=493) believe their health would improve if they reduce their sodium intake [51]. Two studies found that populations are at-risk for poor practices regarding dietary sodium. A study conducted in urban rural areas of Shandon, China recruited adults between the ages of years old (n=15,359) to complete a sodium questionnaire. Results indicated that only 46% of participants were actively trying to 12

24 reduce their sodium intake [52]. A second study conducted in healthy adults between the ages of 35 and 50 years old (n=3,310) in Ontario, Canada asked participants to complete a questionnaire regarding dietary sodium. Results indicated that only 37% of participants were actively trying to reduce their sodium intake. They also found that only 36% of participants strongly agree to always checking food package labels for sodium content [48]. The small body of evidence regarding determinants of sodium intake across the globe has revealed that many healthy adult populations are at risk for low knowledge, poor attitudes, and poor practices regarding dietary sodium. Given the relationship between determinants of sodium intake and self-reported sodium-related behaviors, there is a critical need for interventions aiming to improve the determinants of dietary sodium intake in various populations. 13

25 Chapter 3: Assessing Knowledge, Attitudes, and Practices Regarding Dietary Sodium Intake in a Multi-State Cohort of College Students Abstract Background: College students consume beyond the nationally recommended amount of sodium, a risk factor for hypertension, cardiovascular disease, and stroke. There is a need for well-informed interventions aiming to reduce sodium intake in college students. The purpose of the present study was to assess the knowledge, attitudes, and practices regarding dietary sodium intake in a multi-state cohort of college students in an effort to inform future dietary interventions. Methods: Convenience samples of college students from a Midwestern university (n=169) and a Pacific Island university (n=152) completed a previously validated sodium questionnaire. The questionnaire assessed knowledge (27 items with 5 response options; 1 point maximum assigned for correct answers and 0 for incorrect) with higher score representing higher knowledge, attitudes (4 items on 5-point Likert scale) with higher score representing more positive attitudes, and practices (7 items on 5-point Likert scale) with higher score representing more positive practices. There were two 14

26 additional questions regarding perceived sodium intake and current sodium monitoring that were not included in any specific construct. A scoring system of high (80-100% correct responses), and low (0-79.9% correct responses) was used to characterize total knowledge scores; a scoring system of positive (80-100% positive responses), and poor (0-79.9% positive responses) was used to characterize total attitudes and total practices scores. Results: The Midwest student sample was majority female (64%) and White (81%). The Pacific Island student sample was majority female (66%) and Asian (51%). Overall, college students had low knowledge (mean score of 58%), poor attitudes (mean score of 64%), and poor practices (mean score of 65%) regarding dietary sodium. There were no significant differences in the determinants of sodium intake in students in the Midwest compared to students in the Pacific Islands. There were also no significant differences in the three total construct scores across sex or race at either university. Conclusions: College students have low knowledge, poor attitudes, and poor practices regarding dietary sodium intake, which may be contributing to their excessive sodium consumption. Knowledge, attitudes, and practice may be three important targets for future interventions aiming to reduce sodium consumption. Future studies are needed to investigate the relationship between knowledge, attitudes, and practices and actual sodium consumption in college student populations. 15

27 Background Data from the National Health and Nutrition Examination Survey indicate that nearly one third of adults in the U.S. are affected by hypertension [53]. Hypertension is a well-known risk factor for cardiovascular disease and stroke, the first and fifth leading causes of death, respectively [54]. A multitude of genetic and environmental factors contribute to an increased risk for hypertension, including modifiable lifestyle habits such as smoking status, frequency of physical activity, and dietary behaviors [55]. Among dietary behaviors, excessive sodium intake has been positively associated with hypertension [33, 35]. In order to reduce the risk for adverse health outcomes, Dietary Guidelines for Americans recommends that persons aged 14 years or older consume a maximum of 2,300 mg of sodium per day [1]. Alarmingly, nearly 90% of adults aged 19 years or older consume beyond the tolerable upper intake level of sodium per day [2]. Given the link between high sodium consumption and hypertension, the high prevalence of excessive sodium intake in the U.S. has been marked a public health concern [56]. The development and implementation of strategies to reduce sodium intake in U.S. adult populations has become a national priority. The Institute of Medicine recommends the use of behavior change models when developing educational and motivational programs aiming to reduce consumers sodium intake [56]. Nutrition knowledge and attitudes are two commonly targeted determinants of diet quality used 16

28 in interventions to elicit diet-related behavior change. A deeper understanding and higher knowledge of nutrition is positively associated with a better diet quality [45]. Additionally, more positive attitudes about health and nutrition is associated with healthier dietary practices [9]. Studies in adult populations living in both Western and Eastern countries have shown that knowledge is low regarding the sodium levels in commonly eaten foods, diet-disease relationships, and tolerable upper intake levels [49-50, 57-58]. Additionally, studies in healthy adult populations from various European, North American, and Australian countries have found that attitudes towards reducing sodium intake are negative, and that dietary practices related to sodium consumption are poor [51-52, 59]. While studies have been conducted in multiple countries to characterize the determinants of dietary sodium intake in healthy adult populations, little is known about the knowledge, attitudes, and practices regarding dietary sodium consumption in populations living in the U.S. In order to develop effective, population specific interventions targeted at reducing sodium intake, more needs to be understood about the determinants of sodium intake in various subgroups of the U.S. adult population. College students are one specific subgroup of the U.S. adult population that may be at an increased risk for excessive sodium consumption [60]. The transition into college is a time period of growing independence when many young adults begin making their own decisions about the type, size, and timing of their meals [13, 61]. Numerous studies have found that college students engage in poor dietary habits, 17

29 including excessive sodium intake [14]. Common practices among students include frequent snacking and fast food consumption, high intake of high-calorie, high-fat meals, and low intake of fruits and vegetables [41, 62]. Eating patterns formed during young adulthood often transcend into older adulthood, therefore, establishing appropriate sodium consumption patterns during this time period may be a critical step in reducing the risk for hypertension development later in life [15]. While the majority of U.S. college students may be at risk for poor dietary practices, certain subgroups of students may be at an even higher risk for poor diet quality. Males may be at a higher risk than females for poor nutrition knowledge and attitudes regarding dietary sodium [48]. Additionally, males are known to engage in poor dietary practices, such as consuming high-sodium fast food items, more often than females [63]. Studies have also found racial disparities in nutrition knowledge, with minority participants being at a higher risk than white participants for low knowledge [64]. Understanding the disparities in the current levels of sodium knowledge, attitudes, and practices by sex and race may help to inform sodium-related behavior-change interventions and strategies for college student populations [65, 66]. The purpose of the present study was to assess the knowledge, attitudes, and practices regarding dietary sodium in student participants from two geographically diverse universities. With numerous studies concluding that college students consume excessive sodium, the hypothesis was that students would have low knowledge, poor attitudes, and poor practices regarding dietary sodium. Additional sub-study exploratory 18

30 analyses were performed to assess discrepancies in sodium knowledge, attitudes, and practices by sex and race at each university. Ideally, the results observed in this study would be used to inform and develop behavior-change interventions and strategies aiming to reduce sodium intake in U.S. college student populations. Methods Study Design The present study was a collaboration between The Ohio State University (OSU) and the University of Hawaii at Manoa (UH). This study was a cross-sectional, descriptive study that utilized convenience sampling of students enrolled in introductory level general education courses at two universities, OSU and UH, to create representative samples of U.S. college students in two distinct, geographically diverse regions of the country. All information was collected via a previously-validated, self-administered online sodium questionnaire tool. Students were provided with online gift cards valuing $2.00 for participation in the study. Setting This study was conducted on the main campuses OSU and UH, a Mid-West and Pacific Island university, respectively. The student demographic of OSU is majority White (81%), followed by Asian (6%), Black (5%), Hispanic (4%), Multiracial (3%), and Other (1%) [67]. The student demographic of UH is majority Asian (37%), followed by White 19

31 (22%), Pacific Islander (17%), Multiracial (14%), Other (6 %), Hispanic (2%), and Black (2%) [68]. The difference in demographics prompted the comparison of results across the two geographically and demographically diverse universities. This study and all accompanying procedures were approved by the Institutional Review Boards at both OSU and UH. Participants All professors of introductory level general education courses at both universities were invited via to invite their students to participate in the study during the fall of The included study information and a link to the self-administered, online questionnaire. Professors were encouraged to inform their students about the study through in-person class announcements and to provide the link to the online questionnaire through and through their course webpage. At OSU and UH, the survey was accessible for 14 days following the release of the recruitment . In January of 2015, a second recruitment was released at the OSU site in an effort to increase participation. The survey was accessible for an additional 7 days following the release of the second recruitment . Any student enrolled in introductory level general education courses at OSU and UH that did not meet any exclusion criteria was eligible to participate. Each participant was guided through a series of online questions prior to gaining access to the questionnaire to determine their eligibility for the study. Students were ineligible to 20

32 participate if they declared their major of study as Nutrition, Public Health, Nursing or Medicine. Students were also ineligible if they were pregnant, had any medically related dietary restrictions (including but not limited to diabetes, dyslipidemia, and hypertension), and/or had a history of eating disorders. Sodium Questionnaire Participants accessed the self-administered, online questionnaire via the website, Surveymonkey.com [69]. The survey was accessible for the duration of the 14- day study period at UH and the 21-day study period at OSU. Questionnaires that were missing more than one third of responses were considered incomplete and removed from the final analyses. Additionally, any questionnaires that were completed in less than one third of the average completion time were not included in the final analyses. The sodium questionnaire items were developed from two previously validated questionnaires [50, 70]. The questionnaire assessed demographic information and three main constructs regarding dietary sodium intake: i) knowledge; ii) attitudes; and iii) practices (Appendix A). The questionnaire was previously assessed for content validity. A panel of nutrition experts (n=4) were asked to review each question of the survey and analyze items for clear wording and cultural appropriateness, with an emphasis on clarity and simplicity. Each item was rated in terms of whether the knowledge, attitude, or practice measured by the item was Essential, Useful, but not essential, or Not necessary to 21

33 the operationalization of the theoretical construct. The questionnaire was revised using the response and counsel of the expert panel. Additionally, the questionnaire was assessed for face validity. In-depth interviews with college students (n=10) were utilized to assess the readability of the questionnaire. Participants were asked to review each question for clarity and relevance. They were instructed to respond to each item as he or she typically would, explain each question in his or her own words, and also provide recommendations for improvement. Each interview was videotaped, transcribed verbatim, and then analyzed to determine aspects of the questionnaire that warranted revision. The data collected from the present study was used to assess the internal consistency of the questionnaire tool. A separate subscale was developed for each of the three theoretical constructs. Cronbach s alpha coefficients for the knowledge, attitudes, and practices constructs were 0.61, 0.77, and 0.58, respectively. Each subscale met the standards for modest to acceptable Cronbach alpha coefficients for internal consistency ( ) [71]. Outcome Measures Demographics. The sodium questionnaire consisted of two blocks of questions. The first block of questions consisted of ten items describing participant demographic information. Variables measured included age, sex, self-reported racial ancestry, place 22

34 of origin (local, domestic, international), class standing, academic major, annual household income, and family history of hypertension. Self-Report Anthropometrics. Additionally, self-reported height and weight were collected to calculate participant BMI values. Personal Determinants. The second block of questions consisted of three sections including knowledge, attitudes, and practices regarding dietary sodium, and also two additional questions not grouped into a specific construct. Knowledge. The knowledge section consisted of 27 items with 5 varying response options each. Each question had a maximum score of 1 point creating a maximum possible total knowledge score of 27 points, with a higher score representing higher knowledge regarding dietary sodium. A high knowledge score was defined to be 21.5 points (80-100% correct responses). A low knowledge score was defined to be < 21.5 points (0-79.9% correct responses). The knowledge section evaluated knowledge regarding common misconceptions about sodium, diet-disease relationships related to sodium, the sodium content of commonly eaten foods, the relationship between salt and sodium, national sodium intake recommendations, and food label comprehension. For questions pertaining to common misconceptions about sodium and diet-disease relationships, participants were asked to indicate whether the statements were true or false. Common misconceptions and diet-disease relationship questions consisted of 5 response options each which included, Definitely not true, Probably not true, Not sure, Probably true, and 23

35 Definitely true. For misconceptions and diet-disease relationships that were false, participants received 1 point for correctly selecting Definitely not true indicating certainty in their correct response, 0.5 points for correctly selecting Probably not true indicating uncertainty in their correct response, and 0 points for all other responses. Scoring was reversed for misconceptions and diet-disease relationships that were true, with participants receiving 1 point for correctly selecting Definitely true, 0.5 points for correctly selecting Probably true, and 0 points for all other response options. For questions pertaining the sodium content in commonly eaten foods, participants were asked to indicate the relative sodium content of commonly eaten foods in terms of low, moderate, and high sodium levels per serving. Each sodium content question listed one commonly eaten food and had 4 response options each which included, High, Moderate, Low, and Don t know/not sure. Participants received 1 point for correctly selecting the relative sodium content for each commonly eaten food, and received 0 points for all other responses. For the question pertaining to the relationship between salt and sodium, participants were given multiple choice options and asked to indicate which correctly identified the relationship. The salt and sodium relationship question had 4 response options which included, They are the same, Salt contains sodium, Sodium contains salt, and I do not know/not sure. Participants received 1 point for correctly selecting that Salt contains sodium, and received 0 points for all other responses. 24

36 For the question pertaining to the national sodium intake recommendation, participants were given multiple choice options and asked to indicate which correctly identified the maximum amount of sodium most people should consume in a day. The sodium recommendation question had 5 response options which included, 3,400 mg, 2,300 mg, 1,500 mg, 500 mg, and I don t know/not sure. Participants received 1 point for correctly selecting 2,300 mg, and received 0 points for all other responses. Finally, for the question pertaining to food label comprehension, participants were given multiple choice options and asked to identify which sandwich nutrition label showed the highest sodium content per severing. The food label comprehension question had 3 response options which included, Sandwich A, Sandwich B, and Sandwich C. Participants received 1 point for correctly selecting Sandwich C, and received 0 points for all other responses. For all knowledge items, participants received 0 points for non-responses. Attitudes. The attitudes construct section consisted of 4 items on a 5-point Likert scale. Each attitude item listed a statement and asked participants to indicate how much they agreed with the statement. For each item, response options included, Strongly agree, Agree, Neutral, Disagree, and Strongly disagree. Each question had a maximum score of 5 points creating a maximum possible total attitude score of 20 points, with a higher score representing more positive attitudes regarding dietary sodium. A positive attitude score was defined to be 16.0 points (80-100% positive attitude responses). A poor attitude score was defined to be points (0-79.9% 25

37 positive attitude responses). For statements representing positive attitudes, participants received 5 points for selecting Strongly agree, 4 points for selecting Agree, 3 points for selecting Neutral, 2 points for selecting Disagree and 1 point for selecting Strongly disagree. For all attitude items, participants received 0 points for non-responses. Practices. The practice section consisted of 7 items with 5 response options each. The section included 1 question assessing frequency of home food preparation. Participants were asked to indicate how often they prepare food in their apartment or dorm and response options included, Daily, 5-6 times per week, 3-4 times per week, 2 times per week or less, and Never. Next, the following 6 practice statements asked participants to indicate the relative frequency that they performed specific sodiumrelated dietary behaviors. Response options for the practice statements included, Never, Rarely, Sometimes, Often, Always, Don t know, and Not applicable. Each question had a maximum score of 5 points creating a maximum possible total practice score of 35 points, with a higher score representing more positive practices regarding dietary sodium. A positive practice score was defined to be 28.0 points (80-100% positive practice responses). A poor practice score was defined to be <28.0 points (0-79.9% positive practice responses). For the practice question assessing frequency of food preparation, participants received 5 points for selecting Daily, 4 points for selecting 5-6 times per week, 3 points for selecting 3-4 times per week, 2 points for selecting 2 times per week or less, and 1 point for selecting Never. Participants received 0 points for non-responses. 26

38 For the remaining 6 practice items, on statements representing poor dietary practices, participants received 5 points for selecting Never, 4 points for selecting Rarely, 3 points for selecting Sometimes, 2 points for selecting Often, and 1 point for selecting Always. For statements representing positive dietary practices, scoring was reversed. Participants received 0 points for selecting Don t know, Not applicable, and/or non-responses. Additional Items. The questionnaire consisted of two additional questions that were not included in any of the three constructs or total scores. One of the additional questions asked participants to indicate their self-perceived sodium consumption. Participants were asked how much sodium do they think they consume and response options included, Too much, Right amount, Too little, and Don t know. Participants received 1 point for selecting Right amount, and 0 points for all other responses and non-responses. The second additional question asked participants to indicate their current sodium monitoring habits. Participants were asked if they were currently watching or reducing their sodium intake and response options included, Yes, and No. Participants received 1 point for selecting Yes, and 0 points for selecting No and nonresponses. Data Analysis Between-Group Analyses. Descriptive statistics such as means, standard deviations, and frequencies were used as appropriate to summarize demographic data 27

39 separately for the OSU sample and for the UH sample. Chi-square analyses for categorical variables and paired t-tests for continuous variables were used as appropriate to compare demographics across the two universities. Then, total scores for the knowledge, attitudes, and practices constructs were reported separately for the OSU sample and for the UH sample. Paired t-tests were used to compare the mean total scores for each construct across the two universities. Frequencies and percentages of participants falling into the high or low construct score categories were reported for both OSU and UH. Chi-square analysis was used to compare the frequencies of high and low construct scores across the two universities. Next, responses for each individual questionnaire item were reported separately for OSU and UH. For the individual knowledge items with only one correct response, chisquare analysis was used to compare frequency of the correct responses across universities. For the true/false misconception and diet-disease relationship questions that were true, the frequency of correct responses with certainty (i.e. Definitely true ), and the frequency of correct responses without certainty (i.e. Probably true ), were first reported separately. Then, the separate Definitely true and Probably true categories were collapsed into one overall combined correct response category for each individual item. Chi-square analysis was used to compare frequency of the combined correct response category for each item across the two universities. The same analysis was performed in reverse for true/false misconception and diet-disease relationship 28

40 questions that were false by collapsing the categories Definitely not true and Probably not true. For each individual attitude item, similar chi-square analysis was used to compare frequency of positive attitudes across universities. For each item, the frequency of responses indicating Strongly agree and Agree with the positive attitude statements were reported separately. Then, the Strongly agree and Agree categories were collapsed into one overall combined positive response category for each individual attitude item. Chi-square analysis was used to compare frequency of the overall combined positive responses category for each item across the two universities. Similarly, for each practice question, a similar chi-square analysis was used to compare frequency of positive practices across the two universities. For the item assessing frequency of home food preparation, the frequency of responses indicating Daily and 5-6 times per week were reported separately. Then, the Daily and 5-6 times per week categories were collapsed into one overall combined positive response category for the individual practice item. Next, for the remaining practice items, the frequency of Never and Rarely responses to poor dietary behavior statements were reported separately. Then, the Never and Rarely categories were collapsed into one overall combined positive response category for each individual practice item that represented a poor dietary behavior. Chi-square analysis was used to compare frequency of overall combined positive response category for each item across the two universities. The same analysis was performed in reverse for practice statements that 29