ABSTRACT

Background. College students’ modifiable health behaviors, including unhealthful eating patterns, predispose them to risk for future cardiometabolic conditions.

Purpose. This novel 8-week randomized control parallel-arm study compared the effects of a daily 18-hour Time-Restricted Feeding protocol vs. an 8-hour fast on diet quality in college students. Secondary outcomes were resting morning blood pressure, biomarkers of glucose regulation, biomarkers of lipid metabolism, and anthropometric measures.

Methods. Eighteen healthy college students (age = 23 ± 4 years; BMI = 23.2 ± 2.3 kg/m2; MET = 58.8 ± 32.9 min/wk) completed this study. Participants were randomized to a daily 18-hour fasting protocol (Intervention; n = 8) or a daily 8-hour fasting protocol (Control; n = 10) for eight weeks. One ‘cheat’ day was permitted each week. Outcomes were measured at weeks 0 (baseline), 4, and 8. A non-parametric Mann Whitney U test was used to compare the week 4 change from baseline between groups. Statistical significance was set at p≤0.05.

Results. Diet quality (p = 0.030) and body weight (p = 0.016) improved from baseline to week 4 for the INV group in comparison to the CON group. The data suggest these improvements may be related to reductions in snacking frequency and increased breakfast consumption. Fasting blood glucose and hip circumference tended to improve for the INV group in comparison to the CON group (p = 0.091 and p = 0.100). However, saturated fat intake tended to increase in the INV group in comparison to the CON group (p = 0.064). Finally, there were no treatment differences between groups (p>0.05) for the 4-week change in total calories, dietary vitamin C, added sugars, resting systolic blood pressure, resting diastolic blood pressure, insulin, homeostatic model assessment for insulin resistance (HOMA-IR), low-density lipoprotein (LDL) cholesterol, triglycerides, high-density lipoprotein (HDL) cholesterol, waist circumference, or MET.

Conclusion. These data, although preliminary, suggest that the 18-hour fasting protocol was effective for improving diet quality and reducing weight in comparison to the 8-hour fasting protocol in healthy college students. Future intervention trials will need to confirm these findings and determine the long-term relevance of these improvements for health outcomes.

Chronic diseases, such as diabetes, heart disease, and cancer are leading causes of death in the United States. Although they result from a host of personal and environmental factors, diet remains a critical way to reduce the risk. Plant-based diets in particular are associated with reduction in risk for chronic disease due to an intake that closely mirrors the Dietary Guidelines for fruit and vegetable consumption, fiber, and fat intake. Additionally, plant-based diets offer a sustainable alternative in relation to food production as they often require fewer natural resources overall.

While there are many benefits to following a plant-based diet, potential concerns arise as well. Certain micronutrients can be lacking and protein intake can be inadequate without careful consideration of dietary intake. Protein is especially important for its role in maintaining lean body mass, which allows individuals to function in activities of daily living. Plant-based sources of protein are often less digestible; therefore, those consuming vegetarian and vegan diets may benefit from increased protein intake for preservation and perhaps improved lean body mass as well as strength changes.

Recent research has shown that vegetarians had significantly less muscle mass compared to omnivores despite similar amounts of protein intake in grams per day. Other research has shown that vegetarians do not necessarily see an increase in muscle mass when exposed to resistance exercise, whereas those following an omnivorous diet or lacto-ovo-vegetarian diet do. However, other studies have found that vegetarians can achieve increases in lean body mass comparable to omnivores if 30g/meal of plant-based protein is ingested consistently.

It remains unclear what effect protein supplementation might have on strength and muscle mass among sedentary plant-based eaters. As such, the present study assessed sedentary vegetarian and vegan individuals as to whether increases in dietary plant-based protein could elicit changes in body composition, hand grip and lower body strength independent of exercise. After an 8-week intervention, no significant differences for lean body mass or strength were noted. Results are discussed in the context of trial integrity and supplement consumption issues.

Most American children consume less than the recommend amount of fruits and vegetables (F&V), 74% and 84%, respectively. Eating too few F&V in childhood is associated with increased risk of cardiovascular disease, hypertension, respiratory symptoms, and some cancers later in life. Adequate F&V consumption favorably impacts antioxidant status, gut flora, mood, and cognitive functioning. Nutrients such as vitamin C and fiber are only naturally occurring in plant foods. For many children, school lunches are an important source of F&V. This pilot study assessed the feasibility of providing condiments to increase children’s consumption of salad bar F&V in an elementary school cafeteria at lunchtime. The trial site was a single Title 1 elementary school in a large, urban district in the greater Phoenix metropolitan area. Taste tests were conducted on three convenience samples of children in grades 3 – 7, aged 8 – 12 years (n=57) to identify the most popular condiment flavors. The five highest rated flavors were made available daily at a “flavor station” in the school’s lunchroom for three consecutive weeks during the Fall 2018 semester. Descriptive and inferential statistics were used to analyze data. A cost analysis was conducted for capital outlays related to the flavor station. School employee perceptions of F&V and the flavor station were assessed via posttest online surveys. Peanut butter was rated the best tasting condiment by children and was the only condiment that increased in popularity throughout the intervention. Overall, daily F&V consumption increased 17 g per child. There was a linear increase in F&V consumption during the study (r=0.986; P=0.014). As a proportion of the total F&V selected, F&V waste decreased by nearly 3%. The average daily cost of providing the flavor station was $0.09 per student. Sixty-five percent of school staff felt that the flavor station should continue at their school. Peanut butter is an affordable, nutrient-dense food that accommodates the USDA Food and Nutrition Service meal patterns and nutrition standards, and thus, is a viable strategy for increasing F&V consumption and decreasing F&V waste. The results herein inform the development of future interventions to improve the palatability of F&V for children.

Multiple health-related benefits have been associated with adherence to plant-based diets, including vegan, vegetarian, and pescatarian dietary patterns. Despite a consistent body of evidence on the importance of healthy diets, Americans continue to find difficulty in establishing and adhering to dietary goals that could elicit long-term health benefits. Recent research suggests an important role for goal-setting strategies in health behavior change attempts, with some success shown in dietary behavior change, specifically. The current study thus aimed to explore whether having multiple goals alongside one primary goal of following a vegetarian, vegan, or pescatarian diet would increase the achievability of that goal. Participants of this study were broken into two groups: currently following a plant-based diet (ADHERE) and striving to follow a plant-based diet (STRIVE). Researchers hypothesized that the number of health and/or diet related alternative goals set by participants would differ between the two groups, that the ADHERE group would report that their alternative goals were more helpful and less interfering in achieving their dietary goal than the STRIVE group, and that a higher rank of importance of the dietary goal would predict being in the ADHERE group. Results showed that the number of health and/or diet related alternative goals did not differ between groups. The ADHERE group and STRIVE group did not have significantly different helpfulness and interference reports. Although, in an exploratory analysis, it was shown that those participants who reported at least 2 health/diet related alternative goals found those goals to be significantly more helpful than those who reported 0 or 1 health/diet goal. Results showed that rank of dietary goal did not predict group assignment. Overall, the results from this study showed that the type of alternative goal was very important when pursuit of multiple goals was in effect. Type of alternative goal seemed to be a higher predictor of the perceived helpfulness of the alternative goals than previous achievement of goals.

Vegetarian diets can provide an abundance of nutrients when planned with care. However, research suggests that vegetarian diets may have lower protein quality than omnivore diets. Current protein recommendations assume that vegetarians obtain a majority of their protein from animal products, like dairy and eggs. Studies have shown that this assumption may not be valid. The recommended dietary allowance (RDA) may not be adequate in vegetarian populations with high protein requirements. The purpose of this study is to analyze dietary protein quality using the DIAAS (Digestible Indispensable Amino Acid Score) method in both vegetarian and omnivore endurance athletes. 38 omnivores and 22 vegetarians submitted 7-day food records which were assessed using nutrition analysis software (Food Processor, ESHA Research, Salem, OR, USA). Dietary intake data was used to calculate DIAAS and determine the amount of available dietary protein in subject diets. Dietary data was compared with the subjects’ lean body mass (obtained using DEXA scan technology), and strength (quantified using peak torque of leg extension and flexion using an isokinetic dynamometer). Statistical analyses revealed significantly higher available protein intake in the omnivore athletes (p<.001). There were significant correlations between available protein intake and strength (p=.016) and available protein intake and lean body mass (p<.001). Omnivore subjects had higher lean body mass than vegetarian subjects (p=.011). These results suggest that vegetarian athletes may benefit from higher overall protein intakes to make up for lower dietary protein quality.

Mobile healthy food retailers are a novel alleviation technique to address disparities in access to urban produce stores in food desert communities. Such retailers, which tend to exclusively stock produce items, have become significantly more popular in the past decade, but many are unable to achieve economic sustainability. Therefore, when local and federal grants and scholarships are no longer available for a mobile food retailer, they must stop operating which poses serious health risks to consumers who rely on their services.

To address these issues, a framework was established in this dissertation to aid mobile food retailers with reaching economic sustainability by addressing two key operational decisions. The first decision was the stocked product mix of the mobile retailer. In this problem, it was assumed that mobile retailers want to balance the health, consumer cost, and retailer profitability of their product mix. The second investigated decision was the scheduling and routing plan of the mobile retailer. In this problem, it was assumed that mobile retailers operate similarly to traditional distribution vehicles with the exception that their customers are willing to travel between service locations so long as they are in close proximity.

For each of these problems, multiple formulations were developed which address many of the nuances for most existing mobile food retailers. For each problem, a combination of exact and heuristic solution procedures were developed with many utilizing software independent methodologies as it was assumed that mobile retailers would not have access to advanced computational software. Extensive computational tests were performed on these algorithm with the findings demonstrating the advantages of the developed procedures over other algorithms and commercial software.

The applicability of these techniques to mobile food retailers was demonstrated through a case study on a local Phoenix, AZ mobile retailer. Both the product mix and routing of the retailer were evaluated using the developed tools under a variety of conditions and assumptions. The results from this study clearly demonstrate that improved decision making can result in improved profits and longitudinal sustainability for the Phoenix mobile food retailer and similar entities.

Food deserts are defined as regions with low average income, low accessibility to grocery stores, and high adverse health outcomes. Food deserts have thus become an important area of public health research, and many actions are being taken across the country to "solve" the variety of problems food deserts represent. Despite the many solutions promoted to improve food security, healthy food access, and health outcomes among individuals living in food desert areas, not all activities have been critically assessed for their potential for sustained impact. Further, little research has been conducted in the state of Arizona regarding food-related ‘assets’ available to employ in solutions to food desert problems. This analysis gives a glimpse into the complex nature of food deserts, which are impacted by a variety of factors, from economics to public policy to culture. It further provides a current assessment of available assets for potential use in ameliorating the negative impacts of food deserts on Arizona citizens. A graphical asset mapping analysis offers specific consideration of farmers markets and food hubs to possibly aid food deserts in the state.

Food banks are the foundation of the emergency food network, and while their chief mission is to mitigate hunger, the rise in obesity and other diet-related diseases among clientele has incited the need for better nutritional control with regards to procurement of inventory at food banks. The purpose of this research was to determine if procured inventory at United Food Bank in Mesa, Arizona could meet minimum MyPlate recommendations for a typical food bank client and what implications the results could have for future policy. Inventory data was obtained from United Food Bank for fiscal year 2013-2014 and analyzed utilizing the MyPlate Analysis Program to determine contributions of each food category to MyPlate recommendations. Inventory was separated by MyPlate food category and analyzed to determine contribution towards a meal built around MyPlate recommendations. Results showed that the inventory could meet the minimum requirements for protein and grains for a family of four for at least three days, the amount of time an emergency food box is designed to last. On the contrary, the inventory did not meet minimum vegetable, fruit or dairy requirements. These results indicate that typical food bank inventory does not meet USDA MyPlate recommendations and that having nutritional policy in place could potentially drive donations and purchases to enhance the nutritional quality of future food bank inventory.

Advancing sustainable food systems requires holistic understanding and solutions-oriented approaches that transcend disciplines, so expertise in a variety of subjects is necessary. Proposed solutions are usually technically or socially oriented, but disagreement over the best approach to the future of food dominates the dialogue. Technological optimists argue that scientific advances are necessary to feed the world, but environmental purists believe that reductions in consumption and waste are sufficient and less risky. Life cycle assessment (LCA) helps resolve debates through quantitative analysis of environmental impacts from products which serve the same function. LCA used to compare dietary choices reveals that simple plant-based diets are better for the environment than diets that include animal products. However, analysis of soy protein isolate (SPI) demonstrates that certain plant-based proteins may be less preferable for the environment than some unprocessed meats in several categories due to additional impacts that come from industrial processing. LCAs' focus on production risks ignoring consumers, but the food system exists to serve consumers, who can be major drivers of change. Therefore, the path to a sustainable food system requires addressing consumption issues as well. Existing methods for advancing sustainable food systems that equate more information with better behavior or performance are insufficient to create change. Addressing food system issues requires sufficient tacit knowledge to understand how arguments are framed, what the supporting content is, the findings of primary sources, and complex and controversial dialogue surrounding innovations and interventions for food system sustainability. This level of expertise is called interactional competence and it is necessary to drive and maintain holistic progress towards sustainability. Development strategies for interactional competence are informed by studying the motivations and strategies utilized by vegans. A new methodology helps advance understanding of expertise development by assessing levels of expertise and reveals insights into how vegans maintain commitment to a principle that influences their daily lives. The study of veganism and expertise reveals that while providing information to debunk fallacies is important, the development of tacit knowledge is fundamental to advance to a stage of competence.

Research related to food deserts, areas with limited access to healthy and affordable food options, has focused primarily on issues of healthy food access, food quality and pricing, dietary outcomes, and increased risk for chronic diseases among residents. However, upstream challenges that might play a major role in the creation and perpetuation of food deserts, namely problems in the supply chain, have been less considered. In this qualitative study, researchers conducted semi-structured interviews with local produce supply chain representatives to understand their perspectives on the barriers to, and potential solutions for, supplying affordable produce to underserved areas in Phoenix, AZ. Through industry and academic experts, six representatives of the supply chain were identified and recruited to take part in one-hour interviews. Interviews were audio-recorded, transcribed, and coded into categories using a general inductive approach. Using the qualitative analysis software NVIVO to assist in data analysis, themes and subthemes emerged. Results suggested that considerable barriers exist among the representatives for supplying fresh, affordable produce in Phoenix-area food deserts, including minimum delivery requirements beyond the needs of the average small store, a desire to work with high-volume customers due to transportation and production costs, and the higher price point of produce for both store owners and consumers. Conversely, opportunities were identified that could be important in overcoming such barriers, including, tax or economic incentives that would make distribution into food deserts financially viable, infrastructural support for the safe handling and storage of fresh foods at existing retail outlets, and the development of novel distribution mechanisms for producers such as mobile markets and food hubs. Future research is needed to determine if these findings are representative of a larger, more diverse sample of Arizona produce supply chain representatives.