Date of Completion

Spring 5-1-2022

Thesis Advisor(s)

Maria-Luz Fernandez

Honors Major

Nutritional Sciences


Cardiovascular Diseases | Dietetics and Clinical Nutrition | Human and Clinical Nutrition | Nutritional and Metabolic Diseases


Background: Diet plays a critical role in the prevention and treatment of metabolic syndrome (MetS). Plant-based diets (PBDs) have demonstrated a broad range of health benefits, including a protective effect against MetS. Most research on this topic has focused on PBDs as a whole, without considering the influence of diet quality. The purpose of this study was to investigate the relationship between plant-based diet quality and biomarkers of MetS.

Methods: Data were obtained from a clinical nutrition study at the University of Connecticut. 29 participants with MetS were included. PBD quality was assessed using 2 measures: healthful PBD index (hPDI) and unhealthful PBD index (uPDI). Higher hPDI represented greater consumption of healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, unsweetened tea and coffee, low-fat dairy), and lower consumption of less-healthy plant foods (sugar-sweetened beverages, refined grains, potatoes, sweets, high-fat dairy). Higher uPDI represented greater consumption of less-healthy plant foods and lower consumption of healthy plant foods. Both indices were determined by measuring the number of healthful and unhealthful plant foods consumed over a 3-day period. For each participant, hPDI and uPDI scores were calculated at both baseline (2 weeks) and at 9-weeks follow-up. Participants were divided into quintiles according to their hPDI and uPDI scores. Unpaired t-tests were performed to assess differences in mean biomarkers between quintiles, for both hPDI and uPDI. Correlation analyses were performed to investigate cross-sectional associations between biomarker measures and PBD quality scores.

Results: Using baseline data, mean weight was significantly lower in hPDI quintile 5 compared to hPDI quintile 1, and significantly higher in uPDI quintile 5 compared to uPDI quintile 1 (p < .05). Significant associations were observed between PBD quality score and weight at baseline, with hPDI inversely associated with weight (r = -.445, p < .05), and uPDI positively associated with weight (r = .437, p < .05). Using follow-up data, HDL-C was significantly associated with hPDI (r = .411, p < .05) and significantly associated with uPDI (r = -.411, p < .05).

Conclusions: In individuals with metabolic syndrome, adherence to a healthful plant-based diet was associated with lower weight and higher HDL cholesterol, highlighting the influence of diet quality on the health effects associated with plant-based diets.