IMPORTANCE: Overweight/obesity, dyslipidemia, and elevated blood pressure (BP) are increasingly common among U.S. adolescents and increase risk for development of cardiovascular disease (CVD) in adulthood. These risk factors are highly influenced by diet and activity levels, both of which are modifiable with appropriate intervention. School-based programs may be an ideal setting for nutrition intervention programs to improve health behaviors, however data examining the effectiveness of such programs is limited, and results have been inconsistent depending on the outcomes examined. OBJECTIVE: Among a sample of adolescents in Michigan participating in Project Healthy Schools (PHS), a multi-component school-based intervention program, the objective of this dissertation is to 1) examine the effectiveness of the PHS program at achieving favorable change in participating students' dietary consumption of foods and/or beverages associated with CVD risk; 2) examine if achievement of optimal consumption of fruits and vegetables, sugar sweetened beverages (SSB) and levels of physical activity (PA) is associated with improvement in blood lipid and BP levels and; 3) determine if change in dietary consumption of foods high in saturated fatty acids (SFA) and trans-fatty acids (TFA) is associated with change in low density lipoprotein cholesterol (LDL-C) concentrations. DESIGN, SETTING, AND PARTICIPANTS: A non-randomized, quasi-experimental pre-post design evaluation of sixth grade students from 94 middle-schools across the state of Michigan enrolled in the first year of a school-based nutrition intervention program between 2005-2019. MEASURES: Measures of dietary intake and PA were collected from a validated health behavior questionnaire administered at baseline and following completion of the 10-week nutrition intervention program. Physiologic outcome measures of a non-fasting lipid profile which included total cholesterol [TC], high-density lipoprotein cholesterol [HDL-C], triglycerides [TG] and calculated low-density lipoprotein cholesterol (LDL-C), as well as systolic and diastolic BP measurements were collected. RESULTS: Intake of fruit and vegetables significantly increased post-intervention, as did consumption of sugary beverages. Students who were more physically active following the PHS intervention had significantly higher post-intervention HDL-C and lower TG levels, whereas students with low SSB intake post-intervention experienced lower post-intervention HDL-C levels compared to students with higher SSB intake. Reduced consumption of high-risk, high fat foods was associated with a significant decrease in mean LDL-C when compared with high consumption at baseline and follow-up. CONCLUSIONS AND FUTURE DIRECTIONS: Significant increases in dietary intake of fruit and vegetable consumption following participation in the intervention program were modest. Improvement in cardiometabolic risk factors were also observed. Students who improved their intake of foods high in saturated and trans-fat experienced the largest decreases in LDL-C post-intervention. The results also suggest that PA in this age group may be an effective way to improve HDL-C and TG levels, especially among high-risk students. Future work should examine whether modest changes in dietary consumption and/or PA levels can promote a meaningful shift in physiological measures of cardiovascular risk over a longer period of time.
Read
